Richtek RT8239A User manual

RT8239A/B/C
®
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Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
©
Ordering Information
Note :
Richtek products are :
`RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
`Suitable for use in SnPb or Pb-free soldering processes.
High Efficiency, Main Power Supply Controller
for Notebook Computers
General Description
The RT8239A/B/C is a dual step down, Switch Mode Power
Supply (SMPS) controller which generates logic supply
voltages for battery powered systems. It includes two
Pulse Width Modulation (PWM) controllers adjustable
from 2V to 5.5V and also two fixed 5V/3.3V linear
regulators. One of the controllers (LDO5) provides
automatic switch over to the BYP1 input connected to
the main SMPS1 output for maximized efficiency. An
optional external charge pump can be monitored through
SECFB (RT8239B/C). Other features include on board
power up sequencing, a power good output, internal soft-
start, and a soft discharge output that prevents negative
voltage during shutdown.
A constant on-time PWM control scheme operates without
sense resistors and assures fast load transient response
while maintaining nearly constant switching frequency. To
eliminate noise in audio applications, an ultrasonic mode
is included, which maintains the switching frequency
above 25kHz. Moreover, a diode emulation mode
maximizes efficiency for light load applications. The
SMPS1/SMPS2 switching frequency can be adjustable
from 200kHz/233kHz to 400kHz/466kHz respectively.
The RT8239A/B/C is available in a WQFN-20L 3x3
package, and operates over an extended temperature range
from −40°C to 85°C.
Features
zz
zz
z5.5V to 25V Input Voltage Range
zz
zz
z2V to 5.5V Output Voltage Range
zz
zz
zNo Current Sense Resistor Needed
zz
zz
z5V/3.3V Linear Regulators
zz
zz
z4700ppm/°°
°°
°C RDS(ON) Current Sensing
zz
zz
zInternal Current Limit Soft-Start and Soft Discharge
Output
zz
zz
zBuilt In OVP/UVP/OCP
zz
zz
zSelectable Operation Mode with Switcher Enable
Control(RT8239A)
zz
zz
zSECFB Input Maintains Charge Pump Voltage
(RT8239B/C)
zz
zz
zPowerGoodIndicator(RT8239B/Cincludes SECFB)
zz
zz
zRoHS Compliant and Halogen Free
Applications
zNotebook computers
zSystem Power Supplies
z3- and 4- Cell Li+ Battery-Powered Device
RT8239A/B/C
Package Type
QW : WQFN-20L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Z : ECO (Ecological Element with
Halogen Free and Pb free)
Pin Function With
A : ENM
B : SECFB
C : SECFB, Ultrasonic Mode

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Pin Configurations
(TOP VIEW)
RT8239B/CRT8239A
WQFN-20L 3x3
BYP1 BOOT1
ENTRIP2
TON
FB1
ENTRIP1
LDO3
LDO5
ENLDO
ENM
PGOOD
BOOT2
PHASE2 PHASE1
UGATE1 LGATE1
FB2 VIN
LGATE2
UGATE2
15
14
13
12
17181920
1
2
3
4
9876
GND
21
115
16
10
LDO3
LDO5
ENTRIP2
TON
FB1
ENTRIP1
ENLDO
SECFB
PGOOD
BOOT2
PHASE2
BYP1 BOOT1 PHASE1 UGATE1 LGATE1
FB2 VIN
LGATE2
UGATE2
15
14
13
12
17181920
1
2
3
4
9876
GND
21
115
16
10
Marking Information
JB=YM
DNN
JB YM
DNN
JB= : Product Code
YMDNN : Date Code
JB : Product Code
YMDNN : Date Code
RT8239A
JC=YM
DNN
JC YM
DNN
JC : Product Code
YMDNN : Date Code
JC= : Product Code
YMDNN : Date Code
RT8239B
JD=YM
DNN
JD YM
DNN
JD : Product Code
YMDNN : Date Code
JD= : Product Code
YMDNN : Date Code
RT8239C

RT8239A/B/C
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Typical Application Circuit
Figure 1. RT8239ANB Main Supply Typical Application Circuit
C8
3.3V
RT8239A
PHASE1
LGATE1
BOOT1
UGATE1
VIN
11
16
19
17
18
PHASE2
LGATE2
BOOT2
UGATE2
FB2
VIN
10µF
8
9
7
10
5
C6
R1
C2
0.1µF
5.5Vto25V
21 (Exposed Pad) GND
N3
L2
C7
0.1µF
R5
N4
R6
6.5k
+
N1
L1C4
C3
5V
0.1µF
R2
N2
R3
15k
+
R4
10k
R7
10k
FB1
1
BYP1
20
10µF
C1
ENLDO
12
R8
100k
R9
100k
ENTRIP2 4
ENTRIP1 2
LDO3 15
C9
4.7µF
LDO5 14
PGOOD 6
R10
100k
C10
5VAlwaysOn
TON
3
RTON
ENM
13
C5
1µF
Chip Enable
3.3VAlwaysOn
VOUT2
VOUT1
10µF

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Figure 2. RT8239B/C NB Main Supply Typical Application Circuit
RT8239B/C
PHASE1
LGATE1
BOOT1
UGATE1
VIN
11
16
19
17
18
PHASE2
LGATE2
BOOT2
UGATE2
FB2
VIN
10µF
8
9
7
10
5
C6
R1
C2
0.1µF
5.5Vto25V
21 (Exposed Pad)
GND
N3
L2
C7
C8
3.3V
0.1µF
R5
N4
R6
6.5k
+
N1
L1C4
C3
5V
0.1µF
R2
N2
R3
15k
+
R4
10k
R7
10k
FB1
1
BYP1
20
10µF
C1
ENLDO
12
R8
100k
R9
100k
ENTRIP2 4
ENTRIP1 2
Off
On
LDO3 15
C9
4.7µF
LDO5 14
PGOOD 6
R10
100k
C10
5VAlwaysOn
TON
3
RTON
C11
0.1µF
C12
0.1µF
SECFB
13
R11
200k
R12
39k
VCP
C13
0.1µF
C14
0.1µF
C5
1µF
C15
3.3VAlwaysOn
VOUT1
VOUT2
10µF

RT8239A/B/C
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Pin No. Pin Name Pin Function
1 FB1 SMPS1 Feedback Input. Connect FB1 to a resistive voltage divider from SMPS1
output to GND for adjustable output from 2V to 5.5V.
2 ENTRIP1
Channel 1 Enable and Current Limit Setting Input. Connect resistor to GND to set
the threshold for Channel 1 synchronous RDS(ON) sense. The GND-PHASE1
current limit threshold is 1/10th the voltage seen at ENTRIP1 over a 0.5V to 3V
range. There is an internal 10μA current source from LDO5 to ENTRIP1. Leave
ENTRIP1 floating or drive it above 4.5V to shut down channel 1.
3 TON ON-Time/Frequency Adjustment Input. Connect to GND with 56kΩto 100kΩ.
4 ENTRIP2
Channel 2 Enable and Current Limit Setting Input. Connect resistor to GND to set
the threshold for Channel 2 synchronous RDS(ON) sense. The GND-PHASE2
current limit threshold is 1/10th the voltage seen at ENTRIP2 over a 0.5V to 3V
range. There is an internal 10μA current source from LDO5 to ENTRIP2. Leave
ENTRIP2 floating or drive it above 4.5V to shut down channel 2.
5 FB2 SMPS2 Feedback Input. Connect FB2 to a resistive voltage divider from SMPS2
output to GND for adjustable output from 2V to 5.5V.
Power Good Output for Channel 1 and Channel 2 (RT8239A).
6 PGOOD
Power Good Output for Channel 1, Channel 2 and SECFB (RT8239B/C).
7 BOOT2
Boost Flying Capacitor Connection for SMPS2. Connect to an external capacitor
according to the typical application circuits.
8 UGATE2
Upper Gate Driver Output for SMPS2. UGATE2 swings between PHASE2 and
BOOT2.
9 PHASE2
Switch Node for SMPS2. PHASE2 is the internal lower supply rail for the UGATE2
high side gate driver. PHASE2 is also the current sense input for the SMPS2.
10 LGATE2 Lower Gate Drive Output for SMSP2. LGATE2 swings between GND and LDO5.
11 VIN Supply Input for LDO5.
12 ENLDO
Master Enable Input. LDO5/LDO3 is enabled if it is within logic high level and
disabled if it is less than the logic low level. Leave ENLDO floating to default
enable LDO5/LDO3.
ENM
(RT8239A)
Mode Selection with Enable Input. Pull up to LDO5 (Ultrasonic mode) or LDO3
(DEM) to turn on both switch Channels. Short to GND for shutdown.
13 SECFB
(RT8239B/C)
Change Pump Feedback Pin. The SECFB is used to monitor the optional external
charge pump. Connect a resistive divider from the change pump output to GND to
detect the output. If SECFB drops below its feedback threshold, an ultrasonic
pulse occurs to refresh the charge pump driven by LGATE1 or LGATE2.
If SECFB drops below its UV threshold, the switcher channels stop working and
enter into discharge-mode. Pull up to LDO5 or LDO3 to disable SECFB UVP
function.
14 LDO5
5V Linear Regulator Output. LDO5 is the supply voltage for the low side MOSFET
driver and also the analog supply voltage for the device. Bypass a minimum 4.7μF
ceramic capacitor to GND
15 LDO3 3.3V Linear Regulator Output. Bypass a minimum 4.7μF ceramic capacitor to
GND.
16 LGATE1 Lower Gate Driver Output for SMPS1. LGATE1 swings between GND and LDO5.
17 PHASE1
Switch Node SMPS1. PHASE1 is the internal lower supply rail for the UGATE1
high side gate driver. PHASE1 is also the current sense input for the SMPS1.
Functional Pin Description

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Function Block Diagram
Pin No. Pin Name Pin Function
18 UGATE1
Upper Gate Driver Output for SMPS1. UGATE1 swings between PHASE1 and
BOOT1.
19 BOOT1
Boost Flying Capacitor Connection for SMPS1. Connect to an external
capacitor according to the typical application circuits.
20 BYP1 Switch Over Source Voltage Input for LDO5.
21 (Exposed Pad) GND Analog Ground and Power Ground. The exposed pad must be soldered to a
large PCB and connected to GND for maximum power dissipation.
ENM (RT8239A)
SECFB (RT8239B/C)
SMPS2
PWM
Buck
Controller
BOOT2
UGATE2
PHASE2
LGATE2
GND
LDO5
FB2
ENTRIP2
PGOOD
SMPS1
PWM
Buck
Controller
BOOT1
UGATE1
PHASE1
LGATE1
LDO5
FB1
ENTRIP1
LDO5 REF
Switch Over Threshold
VIN
LDO5
On Time
TON
LDO3 LDO3
BYP1
Power-On
Sequence
Clear Fault Latch
ENLDO
+ -
LDO5
10µA
LDO5
10µA

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Recommended Operating Conditions (Note 4)
zSupply Input Voltage, VIN ----------------------------------------------------------------------------------------------- 5.5V to 25V
zJunction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C
zAmbient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C
Absolute Maximum Ratings (Note 1)
zVIN, ENLDO to GND ------------------------------------------------------------------------------------------------------ −0.3V to 30V
zBOOTx to PHASEx ------------------------------------------------------------------------------------------------------- −0.3V to 6V
zENTRIPx, FBx, TON, BYP1, PGOOD, LDO5, LDO3, ENM/SECFB to GND ------------------------------- −0.3V to 6V
zPHASEx to GND
DC ----------------------------------------------------------------------------------------------------------------------------- −0.3V to 30V
< 20ns -----------------------------------------------------------------------------------------------------------------------−8V to 38V
zUGATEx to PHASEx
DC ----------------------------------------------------------------------------------------------------------------------------- −0.3V to 6V
< 20ns -----------------------------------------------------------------------------------------------------------------------−5V to 7.5V
zLGATEx to GND
DC ----------------------------------------------------------------------------------------------------------------------------- −0.3V to 6V
< 20ns -----------------------------------------------------------------------------------------------------------------------−2.5V to 7.5V
zPower Dissipation, PD@ TA= 25°C
WQFN-20L 3x3 ------------------------------------------------------------------------------------------------------------ 3.33W
zPackage Thermal Resistance (Note 2)
WQFN-20L 3x3, θJA ------------------------------------------------------------------------------------------------------- 30°C/W
WQFN-20L 3x3, θJC ------------------------------------------------------------------------------------------------------ 7.5°C/W
zLead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------- 260°C
zJunction Temperature ----------------------------------------------------------------------------------------------------- 150°C
zStorage Temperature Range -------------------------------------------------------------------------------------------- −65°C to 150°C
zESD Susceptibility (Note 3)
HBM (Human Body Model) ---------------------------------------------------------------------------------------------- 2kV
Parameter Symbol Test Conditions Min Typ Max Unit
Input Supply
Rising Threshold -- 5.1 5.5
VIN Power On Reset Falling Threshold 3.5 -- 4.5 V
VIN Shutdown Current IVIN_SHDN V
ENLDO = GND -- 20 40
VIN Standby Supply Current IVIN_SBY Both SMPS Off -- 250 350 μA
Quiescent Power Consumption IQBoth SMPSs on, FBx = 2.1V,
BYP1 = 5V, ENM = 3.3V (RT8239A) -- 5 7 mW
SMPS Output and FB Voltage
FBx, CCM Operation -- 2 --
FBx Regulation Voltage VFBx FBx, DEM Operation 1.98 2.006 2.03 V
(VIN = 12V, VENLDO = 5V, VENTRIPx = 2V, VBYP1 = 5V, No Load on LDO5, LDO3, TA= 25°C, unless otherwise specified)
Electrical Characteristics

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Parameter Symbol Test Conditions Min Typ Max Unit
Output Voltage Adjustable
Range SMPS1, SMPS2 2 -- 5.5
SECFB Voltage VSECFB RT8239B 1.92 2 2.08
V
On-Time
VPHASE1 = 2V -- 256 --
On-Time Pulse Width tUGATEx VIN = 20V
RTON = 56kΩVPHASE2 = 2V -- 220 -- ns
Minimum Off-Time tLGATEx V
FBx = 1.8V -- -- 400 ns
fSMPS1 SMPS1 Operating Frequency 200 -- 400
Frequency Range fSMPS2 SMPS2 Operating Frequency 233 -- 466 kHz
Ultrasonic Mode Frequency fASM RT8239C, VPHASEx = 50mV 25 -- -- kHz
Soft-Start
Soft-Start Time tSSx Zero to 200mV Current Limit Threshold
from ENTRIPx Enable -- 2 -- ms
Current Sense
Current Limit Current Source IENTRIPx V
ENTRIPx = 0.9V 9.4 10 10.6 μA
Temperature Coefficient of
IENTRIPx On The Basis of 25°C -- 4700 --
ppm/°C
Current Limit Adjustment
Range VENTRIPx = IENTRIPx x RENTRIPx 0.5 -- 2.7 V
Current Limit Threshold VENTRIPx GND −PHASEx, VENTRIPx = 2V 180 200 225 mV
Zero-Current Threshold VZC GND −PHASEx, FBx = 2.1V -- 3 -- mV
Internal Regulator and Reference
VBYP1 = 0V, ILDO5 < 100mA 4.8 5 5.2
VBYP1 = 0V, ILDO5 < 100mA ,
6.5V < VIN < 25V 4.75 -- 5.25
LDO5 Output Voltage VLDO5
VBYP1 = 0V, ILDO5 < 50mA,
5.5V < VIN < 25V 4.75 -- 5.25
V
LDO5 Output Current ISHORT5 V
BYP1 = 0V, VLDO5 = 4.5V -- 225 -- mA
5V Switchover Threshold VBYP1TH Falling Edge, Rising Edge with FB1
Regulation Point 4.53 4.66 4.79 V
5V Switch RDS(ON) R
BYPSW V BYP1 = 5V, ILDO5 = 50mA -- 1.5 3 Ω
VBYP1 = 0V, ILDO3 < 100mA 3.2 3.3 3.46 V
LDO3 Output Voltage VLDO3 VBYP1 = 5V, ILDO3 < 100mA 3.2 3.3 3.46
LDO3 Output Current ISHORT3 V
BYP1 = 0V, VLDO3 = 2.9V -- 150 -- mA
UVLO
Rising Edge -- 4.35 4.5
LDO5 UVLO Threshold VUVLO5 Falling Edge 3.9 4.05 4.2 V
LDO3 UVLO Threshold VUVLO3 Both SMPS Off -- 2.2 --
Power Good
PGOOD Threshold VPGOOD PGOOD Detect, Rising edge with
soft-start delay time. Hysteresis = 2.5% −14 −10 −6 %
PGOOD Propagation Delay tPD_PGOOD Falling Edge -- 5 -- μs

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Parameter Symbol Test Conditions Min Typ Max Unit
PGOOD Leakage Current ILK_PGOOD High State, Forced to 5.5V -- -- 1 μA
PGOOD Output Low Voltage VSINK_PGOOD I
SINK = 4mA -- -- 0.4 V
SECFB Power Good
Threshold VSFB_PGOOD SECFB with Respect to 2V
(RT8239B/C) 40 50 60 %
Fault Detection
Over Voltage Protection Trip
Threshold VOVP OVP Detect, FBx Rising Edge 108 112 116 %
Over Voltage Protection
Propagation Delay tDLY_OVP Rising Edge -- 5 -- μs
VUVP UVP Detect, FBx Falling Edge. 53 58 63 %
Under Voltage Protection Trip
Threshold VSFB_UVP UVP Detect, SECFB Falling Edge. 0.8 -- 1.2 V
Under Voltage Protection
Shutdown Blanking Time tSSHx From ENTRIPx or ENM Enable -- 5 -- ms
Thermal Shutdown
Thermal Shutdown TSD -- 150 -- °C
Thermal Shutdown Hysteresis ΔTSD -- 10 -- °C
Logic Input
ENTRIPx Input Voltage VENTRIPx Clear Fault Level/SMPSx Off Level 4.5 -- -- V
Rising Edge Threshold 1.2 1.6 2
Falling Edge Threshold 0.9 0.95 1
ENLDO Input Voltage VENLDO
When ENLDO is Floating (Default
Enable) 2.1 -- --
V
Clear Fault Level/SMPSs Off Level -- -- 0.8
SMPSs On, DEM Operation 2.3 -- 3.6
ENM Input Voltage
(RT8239A) VENM
SMPSs On, Ultrasonic Mode
Operation 4.5 -- --
V
IFBx V
FBx = 0V or 5V −1 -- 1
IP13 ENM/SECFB = 0V or 5V −1 -- 1
Input Leakage Current
IENLDO ENLDO = 0V or 5V −1 -- 3
μA
Internal BOOT Switch
Internal Boost Charging
Switch On-Resistance RBOOTx LDO5 to BOOTx, 10mA -- -- 90 Ω
Power MOSFET Drivers
RUGATEsr Source, VBOOTx −VUGATEx = 0.1V -- 5 8
UGATEx On-Resistance RUGATEsk Sink, VUGATEx −VPHASEx = 0.1V -- 2 4
Ω
RLGATEsr Source, VLDO5 −VLGATEx = 0.1V -- 5 8
LGATEx On-Resistance RLGATEsk Sink, VLGATEx = 0.1V -- 1.5 3 Ω
tLGATERx UGATEx Off to LGATEx On -- 30 --
Dead Time tUGATERx LGATEx Off to UGATEx On -- 40 -- ns

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Note 1. Stresses beyond those listed “Absolute Maximum Ratings”may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in
the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2. θJA is measured at TA= 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is
measured at the exposed pad of the package.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.