TDK-Lambda PFH500F-28 series User manual

0 Rev. 2.0 June 11, 2018
PFH500F-28-xxx Series
Instruction Manual
BEFORE USINGTHE POWER SUPPLY UNIT
Be sure to read and understand this instruction manual thoroughly before using this product. Pay attention to all cautions and
warnings before using this product. Incorrect usage could lead to an electrical shock, damage to the unit or a fire hazard.
DANGER
Never use this product in locations where flammable gas or ignitable substances are present. There are risks of igniting these
substances and exploding by an arcing.
WARNING
Do not touch this product or its internal components while circuit is live, or shortly after shut down.
There may be
high voltage or high temperature present and you may receive an electric shock or burn.
While this product is operating, keep your hands and face away from it as you may be injured by an unexpected situation.
Do not make unauthorized changes to this product, otherwise you may receive an electric shock and void your warranty.
Do not drop or insert anything into the product. It might lead to a failure, fire and electric shock.
Do not use this product under unusual conditions such as emission of smoke and/or abnormal smell or audible noise, etc.
It might lead to fire and/or electric shock. In such cases, please contact TDK Lambda. Do not attempt repair by yourself, as it
is dangerous for the user.
Do not operate these products in the presence of condensation. It might lead to fire and electric shock.
CAUTION
This power supply is designed and manufactured for use within an end product such that it is accessible only to trained
SERVICE ENGINEERS.
Confirm that the connections to input/output terminals, and signal terminals are correct as specified in this instruction manual
before turning on the power.
Input voltage, Output current, Output power, ambient temperature, case temperature, and ambient humidity should be kept
within the specifications, otherwise the product may be damaged.
Do not operate and store this product in an environment where condensation might occur. In such case, waterproof treatment
is necessary.
The equipment has been evaluated for use in a Pollution Degree 2 environment.
Do not use this product in environment with a strong electromagnetic field, corrosive gas or conductive substances.
For applications, which require very high reliability, such as nuclear related equipment, medical equipment, traffic control
equipment, etc., it is necessary to provide a fail-safe mechanism in the end equipment.
Do not inject abnormal voltages into the output terminal or signal terminal of this product. The injection of reverse voltage or
over voltage exceeding nominal output voltage into the output terminal or signal terminal might cause damage to internal
components.
Never operate the product under the over-current or short circuit conditions. The failure or other damages may occur.
The output voltage of this power supply unit is considered to be a hazardous energy level (The voltage is 2V or more and the
electric power is 240W or more). It must not be made accessible to users. Protection must be provided for Service Engineers
against indirect contact with the output terminals and/or to prevent tools being dropped across them. While working on this
product, the AC input power must be switched off, and the input, output, +VBus, and -VBus terminal voltages should be at
safe level.
The application circuits and their parameters are for reference only. Be sure to verify effectiveness of these circuits and their
parameters before finalizing the circuit design.
Use a Fast-Blow external fuse to each module to ensure safe operation and compliance with the safety standards to which it is
approved. The recommended input fuse rating within the instructions is as follows: 10A, 250V fast acting fuse. The breaking
capacity and voltage rating of this fuse may be subject to the end use application.

1 Rev. 2.0 June 11, 2018
CAUTION
This information in this document is subject to change without prior notice. Please refer to the latest version of the data sheet,
etc., for the most up-to date specifications of the product.
No part of this document may be copied or reproduced in any form without prior written consent TDK-Lambda.

2 Rev. 2.0 June 11, 2018
1. Model name identification scheme:
PFH 500X – YZ – UVW – R
ROHS
Option Code
Rated Output Voltage
Feature Set (Full or Simple)
Output Power type
Series Name
1-1. Ordering Table:
X
Module
Feature
YZ
Output
(V)
U
Case
Mounting
OVP
(Latch)
OCP
(Non-Latch)
OTP
(Non-Latch)
Pin Length
(0.240”)
Parallel Operation
(Droop Load Share)
F: Full
Features
S: Simple
Features
28: 28V
12: 12V
48: 48V
0: Thru-hole
1: Threaded Standard: Latch Standard: Non-Latch Standard: Non-Latch Standard: 0.240” 0: No Droop Load Share
D: Droop Load Share
-UVW (Option Codes)
-000 Thru-hole Latch Non-Latch Non-Latch 0.240” No Droop Load Share
-0D0 Thru-hole Latch Non-Latch Non-Latch 0.240” With Droop Load Share
-100 Threaded Latch Non-Latch Non-Latch 0.240” No Droop Load Share
-1D0 Threaded Latch Non-Latch Non-Latch 0.240” With Droop Load Share

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2. Module Pinout:
- Module case can be connected to Frame Ground through M3 mounting threaded hole(s).
- Consider terminal contact resistance when connecting AC(L), AC(N), +VBUS, –VBUS, Vout(+), Vout(-).
- Note that +VBUS and –VBUS terminals are primary voltage with high voltage rating (385VDC).
- Do not connect any load(s) across +VBUS and -VBUS terminals. Otherwise, it may damage the module.
PIN FUNCTION PIN FUNCTION
1 AC Input (Line) 11 Secondary Signal GND
2 AC Input (Neutral) 12 Aux Power Supply
3 Vout (-) 13 PMBus Clock
4 Vout (-) 14 PMBus Data
5 ON/OFF 15 PMBus Alert
6 Trim 16 PMBus Address 2
7 Remote Sense (+) 17 PMBus Address 1
8 Vout (+) 18 Inrush Control
9 Vout (+) 19 - Boost Voltage Bus (-VBUS)
10 Power Good 20 + Boost Voltage Bus (+VBUS)

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3. Circuit Block Diagram
EMI Filter Surge Prot.
Inrush
Circuit Bridgeless
PFC Conv.
OTP2
Bulk Caps
Vbus
OVP1
UVP2
OTP1 PMBus
Fuse
Vin Detect
UVP/OVP
Iin Detect
OCP1
PFC
Digital
Controller
URT
DC-DC
Bridge
Converter
Digital
Isolators
DC-DC
Digital
Controller
(OVP/UVP)
URT
Bias
Supplies
Synchro.
Rectifiers
Output Filter
Ipeak
Sense
Io SNS
Vo_sns
Vo
Vbus
Vac
PFC Circuit DC-DC Circuit
Trim
Vaux
Rs
PG
ON/OFF
Relay
NOTE: The blocks with red font are the external components required for the operation of PFH module.
Switching Frequency:
a) PFC Converter (fixed) : 145kHz
b) DC/DC Converter (fixed):
28Vo : 145kHz (primary), 290kHz (secondary ripple)
DC/DC Converter Circuit (fixed)
12Vo & 48Vo : TBD
c) Bias Converter (fixed): 135kHz

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4. Sequence Timing Diagram
Note: PFH series product has a remote ON/OFF pin that is referenced to output return.

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5. Terminal connecting method
In order to use the PFH500 series, this module must be connected with external components according to
Figure 5-1.
Pay attention to the wiring details. If PFH module is connected to wrong terminal(s), the power module will
be damaged.
PFH500 series employs conduction cooling method. Use a heat sink and fan(s) to remove the heat generated
by heavy load operation.
For selection of heat sink(s) and the heat sink heat transfer method, refer to the Power Module Application
Note.
PFH500F
Vo(+)
Vo(-)
AC(L)
AC(N)
C13
C16
Output
Vo(+)
Vo(-)
C5
R1
Case
C6 C7
Earth GND
Vac(L)
Vac(N)
L2
L1
Input
C2 C3
C4
C1
F1
R2
C11 C12
C15
+ VBUS
-VBUS
RS (+)
Vo(+)
Vo(-)
Trim
PG
ON/OFF
Aux Power
PMBus Interface
SGND
RLa
RLb
Inrush
Control
C10
C9
PMBus_Add1
PMBus_Add2
PMBus_Data
PMBus_Clock
PMBus_Alert
Input EMI Filter
for CISPR-22 Class A/B
C14
L=50 mm
Fig.5-1 Basic connection

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F1 : External Input Fuse
PFH500 series module has no internal fuse. Use external fuse to meet Safety Agency requirement.
PFH500 series modules were tested for safety agency certifications (UL, cUL, VDE, etc.) using 10A, 250Vac,
Fast-Acting line fuse. Furthermore, the Fast-Acting type fuse selected must be used with one fuse per each
module.
Also, the line inrush surge current will flow through the PFH module during initial line power application (or
line power switch in). Be sure to check I2t rating of external power switch (or circuit breaker), and external line
fuse to make sure that the fuse will not blow, and/or the circuit breaker will not trip.
Recommended External Fuse：10A, 250V (Fast Acting)
Note) Select fuse based on rated voltage, rated current and surge current capability.
(1) Voltage Ratings
100VAC line : AC125V
200VAC line : AC250V
(2) Current Ratings
Rated current is determined by the maximum input current based on operating conditions and can be
calculated by the following formula.
(Arms)
PFη(min)Vin Pout
(max)Iin  (Formula 5-1)
Iin (max) : Maximum Input Current
Pout : Maximum Output Power
Vin (min) : Minimum Input Voltage
η : Efficiency
PF : Power Factor
For Efficiency and Power Factor values, refer to separate document “PFH500F Series Evaluation Data”.
C1 and C4: 1uF; C5: 2.2uF (Film Capacitor or Class X Safety Capacitor)
These capacitors are connected across the lines to protect against differential mode interference. Their failure
does not create conditions for electric shock, although it can generate a fire risk if failed. Since the X cap is
connected across the line and neutral, the current flowing through the cap can be high. When selecting X
capacitor, be sure to check the allowable maximum ripple current rating of this capacitor.
TDK Lambda Americas recommends the customers to verify the actual ripple current flowing through each X
capacitor by measuring the capacitor actual current.
Connect C5 as close to the input terminals of PFH500 series power module [i.e. AC(L) and AC(N)] as possible.
Recommended Voltage Rating of X - Capacitors: 250VAC

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L1 and L2 : 6.3mH (Common Mode Choke)
Add common mode chokes as EMI noise countermeasure to protect the EMI noise generated by PFH500 series
module flowing into the ac mains. When using multiple PFH500 series modules in parallel, it is important to
insert the EMI filter stages (including X caps, Y caps, and common mode chokes) for each PFH500 module.
Note: An in-proper designed common mode choke may not help the noise reduction, in fact, it may actually
cause PFH500 series module malfunction due to filter resonance. Consult TDK Lambda for technical
assistance in selecting a right EMI filter.
C2, C3 : 3300pF (Ceramic Capacitor or Class Y Capacitor)
Y-capacitors are designed to enhanced electrical and mechanical reliability standards. Y-capacitors are used in
applications where failure of the capacitor could lead to the danger of electrical shock to the user, if the ground
connection is lost.
Y capacitance values are limited to reduce the current flowing through the capacitor when AC line voltage is
applied. Low capacitance helps to reduce the energy stored to a safe limit when DC voltage is applied. Y
capacitors must be tested to applicable safety standards to qualify them for use as Y-capacitors.
Y capacitors are used to protect against common mode noise generated from the PFH500 series module. Be
sure to consider leakage current requirement of your equipment or instrument when selecting this capacitor.
High withstand voltage are applied across this capacitor depending on the application. Select capacitor with high
withstand voltage rating such as Y2 capacitor (rated voltage: 150Vac to 300vac, peak tested voltage: 5kV).
R1: 470 kΩ,2W
Connect bleeder resistor R1 across ac input terminals as shown in Figure 5-1.
C6, C7: 1000pF (Ceramic Capacitor or Class Y Capacitor)
Add these Y capacitors as EMI common-mode noise countermeasure. Be sure to consider leakage current of
your equipment when selecting these capacitors.
High withstand voltage are applied across this capacitor depending on the application. Select capacitor with high
withstand voltage rating such as Y2 capacitor
Connect C6 as close as possible to AC(L) terminal, C7 as close as possible to AC(N) terminal.
C9, C10: Electrolytic Capacitors
PFH500X: 470µF / 450V/ 105 ºC x 2 in parallel
Refer to “Selection Method of External Bulk Capacitor for Boost Converter” below.
Allowable maximum external capacitance at nominal capacitance value is shown below.
Recommended Voltage Rating: 450VDC (105 ºC rated capacitor)
Recommended Maximum Total Capacitance: 940 µF‐1410 µF

9 Rev. 2.0 June 11, 2018
Notes: 1. Do not connect capacitors with more than the above capacitance value as this could lead to PFH
Series power module damage. Consult TDK Lambda for higher bulk capacitance requirement.
2. When using module below -20℃ambient temperature, AC ripple of boost voltage, output ripple
voltage might be affected by ESR characteristics of the bulk capacitors. Therefore, be sure to verify
characteristics by actual evaluation.
3. One or two high value (e.g. 1 M) bleeder resistors are required to be connected across C9 or C10 to
discharge the bulk cap voltage to a safe level after the Power Off.
C11, C12 : 470 pF to 1000 pF
Connect Y class ceramic or film capacitors as EMI noise countermeasure to reduce high frequency noise.
Capacitors with high voltage rating are needed since a very high test voltage is applied across this capacitor
(between the output terminals and the module metal case) during the Hipot test depending on the application,
and if the metal case is connected to earth ground or equipment frame ground. Connect C11 as close to Vo(+)
terminal as possible, and C12 as close to Vo(-) terminal as possible.
C13: 0.1 µF, 50V ~ 100V (Ceramic Capacitor)
Add this ceramic capacitor 50 mm away from the PFH series module output terminals to help reducing the high
frequency output ripple noise.
C14: 40 µF, 50V ~ 100V or four (4) 10 µF capacitors in parallel (Ceramic Capacitor)
Add this ceramic capacitor 50 mm away from the PFH series module output terminals to help reducing the high
frequency output ripple noise, and also to help the load transient response speed.
C15, C16: Refer to Table 5-1
Connect C15 and C16 at 50mm from the output terminals Vo(+) and Vo(-) of the PFH series power module to
stabilize the module operation.
Note that the output noise ripple and the characteristics of the power module during input line turn off might be
affected by the ESR and ESL values of the selected electrolytic capacitors.
Also, note that output ripple voltage may vary depending on layout of the printed circuit board.
Sudden change in output voltage due to sudden load change or sudden input line voltage change can be reduced
by increasing external output capacitance value.
Table 5-1 Recommended external output capacitance for C15 and C16
Module Output Voltage C15 C16
28V 220 µF, 50V 220 µF, 50V
48V 220 µF, 100V 220 µF, 100V
12V 220 µF, 25V 220 µF, 25V
Notes: 1. Use low-impedance electrolytic capacitors with excellent temperature characteristics.
(Nihon Chemi-con LXY Series or Nichicon PM Series or equivalent rated at least 105 ºC)

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2. For module operation at ambient temperature below -20 ºC, the output ripple voltage will be affected
by ESR characteristics of the electrolytic capacitors. Increase the recommended capacitance values as
shown in table below.
Table 5-2 Recommended external output capacitance (when Ambient Temperature ≦-20 ºC)
Module Output Voltage C15 C16
28V 470 µF, 50V 470 µF, 50V
48V 470 µF, 50V 470 µF, 50V
12V 470 µF, 25V 470 µF, 25V
3. Take note of the maximum allowable ripple current of the electrolytic capacitor used. Especially, for
sudden load current changes, verify actual ripple current and make sure that allowable maximum
ripple current of the external capacitor is not be exceeded.
For connection other than recommended capacitance, be sure to connect the polarity right.
●Selection Method of External Bulk Capacitor for Boost Converter
Boost converter bulk capacitor is determined by intermediate bus voltage ripple, ripple current, and hold-up
time. Select a right capacitor value such that Boost converter bus voltage ripple does not exceed 15Vp-p.
Note: When the ambient temperature is ≤ -20 ºC, the ripple voltage of Boost converter output will increase
due to ESR characteristics. Therefore, verify above characteristics by actual evaluation in the circuit.
For output hold-up time, refer to separate document “PFH500 Series Evaluation Data”, and use appropriate
capacitor up to 1410uF maximum. It is recommended that actual verification is performed.
For allowable capacitor ripple current value, refer to Fig. 5-2.
Use of a capacitor with higher ripple current rating is highly recommended.
0
400
800
1200
1600
2000
0 100 200 300 400 500
Output Power (W)
Ripple Current (mA rms)
Fig. 5-2 Allowable ripple current value
The recommended Boost output bulk capacitance value is ranged from 960 µF to 1410 µF.
1
1
5
VA
2
3
0VA

11 Rev. 2.0 June 11, 2018
Note that reduction of the bulk capacitance affects the module output hold-up time, dynamic line transient
response, and dynamic load transient response characteristics. It is recommended that the verification test is
performed for the entire operating temperature range.
R2: 20Ω - 30Ω
By inserting a thermal fuse inrush resistor between the line filter and the input terminal, AC(L) as shown in Fig.
5-1, the inrush current can be limited to a pre-determined level to avoid the external line fuse from being
blown or the input circuit breaker from being tripped or the bulk capacitors and/or PFH series module internal
parts from being damaged or to avoid the oscillation between the input inductor and the bulk capacitors.
The maximum allowable resistance value is limited by the bulk capacitor bank charging time, and the PFC
boost voltage ramp-up time. A 20Ω thermal resistor is recommended.
Note that PFH500 series module will not operate if this external inrush resistor is not present.
●Selection Method of External Resistor
(1) Calculating Resistance Value for R2:
Resistance can be calculated by the formula below.
)(
_
2Ω
Irush
pkVin
R(Formula 5-2)
R2 : Minimum Resistance Value Required for External Thermal Resistor, R2
Vin_pk : Maximum Input Voltage Peak Value = Maximum Input Voltage (rms) x 2
Irush : Allowed Input Inrush Current Peak Value during Initial Power Switch ON
(2) Required Surge Current Rating:
Sufficient surge current withstanding capability is required for external R2 thermal resistor.
Required Surge Current Rating of R2 can be determined by I2t. (Current squared multiplied by time)
)(
2
2
)_( 2
2
2sA
R
pkVinCb
tI 

(Formula 5-3)
I2t : Thermal Resistor current-squared multiplied by time rating
Cb : Maximum Boost Output Bulk Capacitance
Vin_pk : Maximum Input Voltage Peak Value = Input Voltage (rms) x 2
R2 : Resistance Value for External Thermal Resistor, R2, Chosen
(3) R2 Maximum Value Limitation:
R2 maximum value is limited by R-C charging time. The higher R2 value, the lower inrush current, but
the longer start-up time will be (also see section 6-3 discussion). PFH series module does not have the
second inrush event. When the ac line is switched on, the ac power source charges the bulk capacitor bank
via the inrush resistor. Once the Boost converter output voltage (or bulk capacitor voltage) reaches about

12 Rev. 2.0 June 11, 2018
70V, the internal bias circuitry starts to work. After a short delay, the PFC controller starts to enable the
PFC converter, which charges the bulk capacitor bank to the regulated voltage level about 385V. The
value of the thermal resistor, R2, limits the PFC converter ramp –up time, especially at low line case.
RL: Inrush Relay, 10A/277Vac (16A/125Vac), 12V coil
The inrush relay is connected in parallel with R2 resistor. As soon as the PFC bus voltage reaches the pre-set
value (close to the peak of the maximum ac line voltage), the PFC controller will enable the inrush control pin
to energize the relay. This method mitigates or even eliminates the second inrush current event during the relay
closing. It is very important to make sure that the relay contacts are opened before applying AC power.
Otherwise, the unwanted inrush current surge will damage PFH series module.
The inrush relay chosen must have the maximum switching voltage ≥ 265Vac. A relay with minimum of 10A,
277Vac rating, and 12V / (15mA to 20mA) nominal coil operating voltage and current is recommended.
6. Explanation of Functions and Precautions
6-1. Input Voltage Range
Input ac voltage source should be a single phase power, ranged from 85 - 265Vrms (47-63Hz).
Connect the PFH series module to any power source that is outside this specified range (above) may lead to
the permanent damages of the power module.
PFH500 series power module is certified by various safety agencies with a certified label indicating
“100-240Vac, 50-60Hz, 8A”.
6-2. Output Voltage Adjustment Range
PFH series module output voltage can be adjusted up and down by connecting a trim resistor to Vout(+) pin or
Vout(-) pin. Care must be taken to prevent the trim up voltage not to exceed 20% of the nominal voltage. Otherwise,
it may activate the module OVP protection function.
Output Voltage Adjustment Range: +/-20% of the nominal output voltage setting
When trimming up the output voltage, the output current needs to be reduced to maintain maximum output power
to be 500W or less. Otherwise, the module can be damaged permanently.
The trim-up and the trim down connections using external resistor are shown in Fig. 6-2, and Figure 6-4. If the
remote sensing feature is NOT used, RS(+) pin needs to be connected to Vout(+) for local sensing. For details on
Remote Sensing function, refer to “6-7. Remote Sensing”.
● Output Voltage Adjustment using Fixed Trim Resistors
With a trim resistor connected between the trim pin and Vout (+) pin, the output voltage is adjusted up. To adjust
the output voltage up a percentage of Vout (%) from Vo,nom, the trim resistor (in k) should be chosen
according to the following equation:

13 Rev. 2.0 June 11, 2018
)2
%
100
%
%)100(
(11.5 ,0
_






 Vref
V
Rnom
uptrim (Formula 5-4)
%=100(Vo,nom - Vdesired) / Vo_nom
Vref=1.22V
500
5000
50000
0 2 4 6 8 10 12 14 16 18 20
Trim Resistance in (kW)
% Increase in Output Voltage, D(%)
Figure 6-1 Trim-up Resistance vs. Percentage Voltage Trim-up
The trim-up resistor (Rt_up) values from +5% to +20%, can be found in Table 6-1. The trim-up circuit
connection is shown in Figure 6-2. Recommended trim resistor should have +/-1% or better tolerance.
Table 6-1 External Trim-up Resistor Value for Various Output Voltage Adjustment
% Trim-up of
Vo_nom (V) Trim-Up Resistance (KΩ) Measured Value (V) Calculated Value (V)
+ 5% 2391.4K 29.3V 29.4V
+ 10% 1250.3K 30.6V 30.8V
+ 15% 869.8K 31.9V 32.2V
+ 20% 679.6K 33.1V 33.6V

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PFH500F
Vo(+)
Vo(-)
AC(L)
AC(N) C16
Vout
Case
C15
+ VBUS
-VBUS
RS (+)
Vo(+)
Vo(-)
Trim
PG
ON/OFF
Aux Power
PMBus Interface
SGND
Inrush
Control
Load
+
-
Rt_up
Figure 6-2 External Trim-up Circuit Connection
With a resistor connected between the trim pin and Vout (-) pin, the output voltage can be adjusted down. To
adjust the output voltage down a percentage of Vout (%) from Vo,nom, the trim resistor should be chosen
according to the following equation (in k).
)2
%
100
(11.5
_


downtrim
R(Formula 5-5)
10
100
1000
10000
0 2 4 6 8 10 12 14 16 18 20
% Decrease in Output Voltage, (%)
Trim Resistance (k
W
)
Figure 6-3 Trim-down Resistance vs. Percentage Voltage Trim-down

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The trim-down resistor (Rt_down) values for the trim-down voltage range from -5% to -40% can be found in
Table 6-2. The trim down connection diagram is shown in Figure 6-4.
Table 6-2 External Trim-down Resistor Value for Various Output Voltage Adjustment
% Trim-down
of Vo_nom (V) Trim-down Resistance (KΩ) Measured Value (V) Calculated Value (V)
- 5% 92K 26.8V 26.6V
- 10% 40.9K 25.5V 25.2V
- 15% 23.9K 23.8V 23.8V
- 20% 15.3K 22.3V 22.4V
- 30% 6.81K 19.1V 19.6V
- 40% 2.56K 16.9V 16.8V
PFH500F
Vo(+)
Vo(-)
AC(L)
AC(N) C16
Vout
Case
C15
+ VBUS
-VBUS
RS (+)
Vo(+)
Vo(-)
Trim
PG
ON/OFF
Aux Power
PMBus Interface
SGND
Inrush
Control
Load
+
-
Rt_down
Fig.6-4 External Trim-down Circuit Connection
6-3. Inrush Current
Input inrush or surge current changes with the thermal fuse resistor (R2) value and the external boost converter bulk
capacitance value (C9 and C10). It is recommended that the actual evaluation test to be performed to confirm the
inrush current value.
The inrush current peak values shown in the specification or data sheet are measured at nominal lines (115Vac and
230Vac), at 25 ºC using the basic connection as shown in Figure 5-1.
The external line fuse should be chosen based on the PFH product label, which can handle the measured inrush
peak current. The circuit breaker if used should be selected in additional to the line fuse.

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6-4. Output Over-Voltage Protection (OVP)
PFH series module is equipped with OVP protection function. The OVP function activates when Vo > the pre-set
OVP trip set-point. When the OVP triggers, the module output will be shut down either with latch or auto-recovery
depending on the option code specified. The standard option of PFH series modules has a latched OVP protection.
When the OVP function activates, first, cut off input ac line power. Afterwards, verify the boost bus voltage has
dropped below 10V. Check for any abnormal conditions. Then, recover output by cycling input line switch on.
The OVP latch can also be reset by turning off the module use of the On/Off pin or PMBus command.
The OVP set-point can be changed via PMBus if a full featured PFH series module is used. On the other hand, the
maximum allowed module output voltage is limited by the pre-set Boost converter bus voltage. Without increasing
this intermediate bus voltage setting, the OVP setting can only be lowered via PMBus. Otherwise, the module will
never be able to reach the OVP triggering point unless it is applied externally.
Care must be taken to avoid applying higher voltage externally to the output terminals of PFH series module.
Otherwise, it may cause the permanent damage to the module.
6-5. Boost (or Bus) Output Over-Voltage and Under-Voltage Protections (BOVP/BUVP)
PFH series module also monitors the Boost Bus voltage to protect it from the over-voltage and the under-voltage
operations. In case it reaches these pre-set points, the module will be shut down, and the PFC converter will also be
shutdown. The module will try to auto-restart after the shutdown. The inhibiting time depends on the value of the
bulk caps and bleeder resistor values used.
6-6. Output Over-Current Protection (OCP)
PFH series module is equipped with various OCP protection functions including input PFC over-current protection,
DC-DC primary side peak current cycle-by-cycle over-current protection, module over-load protection, and short
circuit protection. In normal operation condition as specified by the specification and derating curves, the OCP
protection will not be activated.
The module OCP function triggers when the output current exceeds 105% to 120% of maximum rated DC output
current of specification. The OCP triggering point is also module temperature dependent since the power module
PWB traces are used for the output current sensing. The OCP set-point is temperature compensated, and is also
calibrated during the manufacturing test process.
The module output will automatically recover when the over-load condition or the short circuit is removed.
For the module with non-latching OCP, the module will enter a 2-second hiccup retry sequence once an OCP
condition is detected. The module will try to re-start for 6 times at 2-second hiccup rate. If the over-load condition
remains after the module tried to re-start 6 times, then it will enter a 6-minute hiccup retry sequence. Once the
module enters the 6-minute hiccup mode, it will stay there until the over-load condition is removed, and the module
can operate for at least 7 minutes without any OCP alarms. After that, the module will reset back to a standard 2-
second hiccup time OCP protection mode in case an OCP alarm is detected again after 7 minutes.
When the PFH series module is operated outside the specified input voltage range, the input OCP function may also
be activated to protect the module from drawing excessive input current to damage the module.
PFH series module OCP set-point is fixed, but it can be lowered from its maximum value by PMBus if a full
featured module is used.
Note that continuous short circuit or overload condition might result in power supply over-heating or damage.

17 Rev. 2.0 June 11, 2018
6-7. Module Over-Temperature Protection (OTP)
PFH series module is equipped with internal OTP protection function. There are four (4) OTP protection devices
located at various key locations of the potted module. There are two (2) NTC thermistors, one located on the hot
spot of the PFC converter side, and another on the hot spot of the DC-DC converter side. The digital controller chip
(for both PFC and DC-DC) also has its own internal thermal sensor. The digital controller reads back the
temperature sensed, and disables the operation based on the pre-set OTP reading(s).
When any one of these components hits the temperature trigger point(s), the OTP protection will be activated, and
the module will shut down. The module will re-start after the internal temperature drops below the re-start point,
usually 20 ºC below the trip point. The non-latching auto-restart OTP protection is a standard feature for PFH series
module.
PFH series module OTP set-point(s) also varies with the input line voltage range. The trip point at low line range is
set lower than the trip set-point of high line operation since the module efficiency at low line operation is lower than
the case of high line operation.
The latched OVP protection is possible, but is not recommended since it requires either to cycle the input power or
to cycle the ON-OFF switch to reset the OTP fault providing the measured hot spot temperature dropped 20 ºC or
more. Usually, this reset operation requires operators’ action, which takes time and cost money in most cases.
6-8. Remote Sensing (+RS Terminals)
PFH series module has one remote sensing terminal, RS(+), to compensate for the line drop from the output
terminals to the output load. When the remote sensing is not required, i.e. using local sensing, be sure to short RS(+)
pin to Vout(+) pins. Note that the line drop (the voltage drop due to long wirings) voltage compensation range must
be within the output voltage adjustment range. At any conditions, the maximum output power of PFH module
should not be exceeded.
Before using remote sensing feature, do adequate evaluation to make sure that the module does not have noise
impact at the load terminals. Should a noise filter inductor be inserted between Vo(+) pin(s) and the load terminal,
the RS(+) sense must be connected as local sense, i.e. to Vo(+) terminal. Some precaution in the layout may be
needed. Contact TDK Lambda Customer Support for the helps if needed.
PFH500F
Vo(+)
Vo(-)
AC(L)
AC(N) C16
Vout
Case
C15
+ VBUS
-VBUS
RS (+)
Vo(+)
Vo(-)
Trim
PG
ON/OFF
Aux Power
PMBus Interface
SGND
Inrush
Control
Load
+
-
Voltage Stable at Load Terminals
Fig.6-5 Remote Sensing is used

18 Rev. 2.0 June 11, 2018
PFH500F
Vo(+)
Vo(-)
AC(L)
AC(N) C16
Vout
Case
C15
+ VBUS
-VBUS
RS (+)
Vo(+)
Vo(-)
Trim
PG
ON/OFF
Aux Power
PMBus Interface
SGND
Inrush
Control
Load
+
-
Voltage Stable at Module Output Terminals
Fig.6-6 Remote Sensing is not used (Local Sensing)
6-9. ON-OFF Control (ENA Terminal)
PFH series module has an ON-OFF control pin, which is used to enable (or turn on) or disable (or turn off) the
module. When this pin is low, the PFH module is enabled. Internally, this pin is connecting to a 10Kpull-up
resistor that is in series with 3.3V source. A 0.01uF filter cap is also connected across this pin to the GND.
Maximum sink current of ON-OFF pin: 300µA
Maximum low status voltage for Enable: 1V
Maximum high voltage of ON-OFF Pin: 3.4V
ON-OFF pin references to Vout(-) Signal Ground.
The digital controller inside the module will remember the ON-OFF control status. Should the module be enabled
by ON-OFF pin, then it must be turned off by ON-OFF pin. Try to turn off the module by PMBus (if equipped) will
be ignored. If the module is enabled by PMBus control, then ON-OFF pin control function will be overridden.
Various ON-OFF pin connection schemes are shown below, Figure 6-7a to Figure 6-7d.
PFH500F
Vo(+)
Vo(-)
AC(L)
AC(N) C16
Vout
Case
C15
+ VBUS
-VBUS
RS (+)
Vo(+)
Vo(-)
Trim
PG
ON/OFF
Aux Power
PMBus Interface
SGND
Inrush
Control
Load
+
-
PFH500F
Vo(+)
Vo(-)
AC(L)
AC(N) C16
Vout
Case
C15
+ VBUS
-VBUS
RS (+)
Vo(+)
Vo(-)
Trim
PG
ON/OFF
Aux Power
PMBus Interface
SGND
Inrush
Control
Load
+
-
Fig.6-7a ON-OFF Pin Tied “Active” Fig.6-7b ON-OFF Pin Tied “Active”

19 Rev. 2.0 June 11, 2018
PFH500F
Vo(+)
Vo(-)
AC(L)
AC(N) C16
Vout
Case
C15
+ VBUS
-VBUS
RS (+)
Vo(+)
Vo(-)
Trim
PG
ON/OFF
Aux Power
PMBus Interface
SGND
Inrush
Control
Load
+
-
S1
PFH500F
Vo(+)
Vo(-)
AC(L)
AC(N) C16
Vout
Case
C15
+ VBUS
-VBUS
RS (+)
Vo(+)
Vo(-)
Trim
PG
ON/OFF
Aux Power
PMBus Interface
SGND
Inrush
Control
Load
+
-
S1
Fig.6-7c ON-OFF Control Using Switch Fig.6-7d ON-OFF Control Using Switch”
6-10. Power Good Signal
PFH series module has a Power Good pin to allow the customer to use this pin to either turn on or off their load(s)
or to communicate with their controller and signaling system to monitor the status of PFH module.
When the output voltage of PFH module is within the specified output voltage regulation band together with the
PWM switching of the module, a Power Good signal is activated. An active “Low level” indicates Power Good.
Maximum sink current of Power Good pin: 200mA
Maximum voltage of Power Good Pin: 60V
Some filtering (hardware or software) of the Power Good pin is recommended for the application where a large
load transient taking place constantly. Care must also be taken for the application where multiple PFH modules are
connected in parallel without the ORing diodes or Oring FETs.
Since PFH series module uses a droop load share scheme, a reasonable well load sharing is expected, which should
not complicate the Power Good signal status.
6-11. Auxiliary Bias / Power
The full featured PFH series module also has an Auxiliary Bias Supply pin, references to Vout(-). This auxiliary
bias is internally over-current protected. It is capable of providing a loosely regulated 12V bias (10V ~ 14V, and
200mA maximum current). This bias supply can be used for powering customers’ on-board POLs loads, and other
low power devices such as LEDs, amplifiers, relays, drivers, etc.
6-12. Droop Load Share (Parallel Operation)
The droop load share scheme is used in PFH series module for the optional load sharing needs. The droop load
share scheme senses the module output load current, and then intentionally lowers the output voltage reference,
which then in turns reduces the regulated output voltage as shown in Figure 6-8a.
Use of Oring diodes (Schottky diodes) with same forward voltage drops and same temperature rise characteristics is
required. The use of the Oring diodes is to prevent any negative current from flowing back to the PFH module(s)
due to the synchronous rectification of the secondary side FETs together with the use of the full digital control.