Texas Instruments UCC25600EVM User manual

Using the UCC25600EVM
User's Guide
Literature Number: SLUU361A
April 2009–Revised November 2018

2SLUU361A–April 2009–Revised November 2018
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LLC Resonant Half-Bridge Converter, 300-W Evaluation Module
User's Guide
SLUU361A–April 2009–Revised November 2018
LLC Resonant Half-Bridge Converter,
300-W Evaluation Module
1 Introduction
The UCC25600 evaluation module, EVM (HPA341), is a 300-W LLC resonant half-bridge converter,
providing a regulated output voltage nominally at 12 V at maximum 300 W of load power with reinforced
isolation of AC-DC off-line application between the primary and the secondary, operating from a DC
source of 390 V. The EVM uses the UCC25600 resonant half-bridge controller which integrates built-in
state of the art efficiency boost features with high level protection features to provide cost effective
solutions for LLC resonant half-bridge converter applications. The secondary side uses two daughter
cards, HPA410, with diodes to make rectification.
Proper precautions must be taken when working with the EVM. High voltage levels, over 390 V, and
temperature higher than 70°C are present on the EVM when it is powered on and after power off for a
short time as well. Forced air cooling is required when the EVM is powered on.
2 Description
2.1 Typical Applications
LLC resonant half-bridge converters are seen in applications such as TVs. The converters produce higher
power conversion efficiency from their zero-voltage switching. Such converters are intended to extend to
low-voltage applications such as ATX12 power supplies for computers and servers to obtain better energy
conservation and savings. The EVM provides a platform to evaluate UCC25600 LLC resonant controller
from a PFC input voltage and 12-V output rated at 300-W output power.
2.2 Features
The UCC25600EVM, HPA341, features:
• 300-W Output Power Rating
• High Efficiency 92% Peak and Over 91% at Full Load
• Regulated Output Nominal of 12 V
• Input DC Voltage of 390 V
• Plenty of Test Points to Facilitate the Device Evaluation
• Over-Current Protection
• Output Over-Voltage Protection
• Burst Operation at Light Load

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3 Electrical Performance Specifications
(1) The EVM output may present saw-tooth waveforms or a voltage higher than the regulation point typically about 13.1 V
depending on load levels and the speed when the load is reduced. The saw-tooth waveform is caused by UCC25600 burst
operation. The output voltage of 13.1 V is caused by output over voltage protection.
Table 1. UCC25600EVM Electrical Performance Specifications
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Input Characteristics
Voltage range VIN 375 390 405 VDC
Maximum input current VIN = 390 VDC , IOUT = 25A 0.88 A
Switching frequency VIN = 390 VDC , IOUT = 25A 110 kHz
Output Characteristics
Output voltage VOUT VIN: 390 VDC , IOUT: 1A 11.9 12 12.2 VDC
Load current1(1) VIN: 390 VDC 0 25 A
Continuous output power VIN: 390 VDC 300 W
Line regulation VIN: 375 VDC to 405 VDC , IOUT = 1.0A 5 mV
Load regulation VIN: 390 VDC , IOUT: 1 - 25A 50
Load starting burst(1) VIN: 390 VDC 0.5 A
Ripple and noise (20 MHz BW) VIN: 390 VDC , IOUT = 25A 120 mVpk-pk
Over current threshold, Io_ocp VIN: 390 VDC 30 A
Max power limit VIN: 390 VDC 350 W
Efficiency
Peak VIN = 390 VDC , IOUT = 15 A 92.5%
Full load VIN = 390 VDC , IOUT = 25 A 91%
Operation ambient temperature Full load, forced air cooling 400 LFM 45 °C

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4 Schematic
Figure 1. UCC25600EVM Schematic
5 Test Setup
5.1 List of Test Points
The EVM provides plenty of test points to facilitate the device's evaluation work. All test points are divided
into two major groups – primary test points and secondary test points. Their locations are shown in
Figure 2. The list below helps users to identify the functions of each test point.

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Figure 2. Test Point Location

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Table 2 shown below lists the functions of each test point.
Table 2. UCC25600EVM Test Points
PRIMARY TEST POINTS SECONDARY TEST POINTS
NAME REF DES CONNECTION NAME REF DES CONNECTION
Vin TP1 Module input
voltage + Vxm TP7 T2 pin 12
PGND TP3 Module input
voltage - Vxm TP12 T2 pin 7
Vbias TP20 Primary Bias 12V + VOUT TP9 T2 pin 9 & 10
GND TP23 Primary Bias 12V - VO+ TP10 Output +
SS TP26 UCC25600 SS-pin VO- TP18 Output -
VDD TP22 UCC25600 VCC-pin Loop+ TP19 Loop measure +
GD1 TP24 UCC25600 pin 8 Loop- TP21 Loop measure -
GD2 TP25 UCC25600 pin 5 VOripple TP15 Output ripple
VG5 TP4 Q5 gate
OC TP17 UCC25600 pin 3
VG6 TP11 Q6 gate
SW1 TP6 Switch node of Q5
and Q6
PGND TP16 Power GND
Icr TP2 Resonant tank
current
Vxm TP5 T2 pin 6
Vcr TP13 Resonant capacitor
voltage
OUTB TP14 T3 pin 1
OUTA TP8 T3 pin 4
5.2 Test Equipment
Voltage Source: The input source shall be a constant DC source capable of supplying 390 VDC with
minimum 1.0 ADC current rating.
Multimeters: Multimeters are used to measure the output voltage (DMM1), the input voltage (DMM3), the
output current (DMM2) and the input load current (DMM4).
Output Load: A programmable electronic load is recommended, configurable for constant current mode
and capable of sinking 0 ADC to 25 ADC from 12 VDC. The output voltage can be monitored by connecting a
DC voltmeter, DMM1 to sense pins (TP10 and TP18) shown in Figure 3. A DC current meter, DMM2, may
be inserted in series with the electronic load for accurate output current measurements. Similarly, the input
voltage can be monitored by connecting a DC voltage meter to sense pins (TP1 and TP3). The input
current can be monitored by a DC current meter too. These are shown in Figure 3.
Oscilloscope: Set the oscilloscope channel to AC coupling with 20-MHz bandwidth.

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5.3 Notes on Power Up and Power Down
The following steps are guidelines for power up and power down of the EVM.
1. An ESD workstation is recommended. Make sure that an ionizer is on before the EVM is removed from
the protective packaging and power is applied to the EVM. Electrostatic smock and safety glasses
should also be worn.
2. Power Up
1. Set up an air cooling fan with minimum 400 LFM or 2.0 m/s forced airflow. This airflow direction
should point to the middle of DB1 and DB2 and towards transformer T2. The cooling fan should be
on throughout the test.
2. Prior to connecting the DC input source, limit the source current 1.0 A maximum. Make sure the
DC source is initially set at 390 VDC prior to turning on. Connect the DC source to the EVM as
shown in Figure 3.
3. Connect the current meters DMM2 and DMM4 as shown in Figure 3.
4. Connect the volt meter DMM1 and DMM3 as shown in Figure 3.
5. For operation with a load, connect the electronic load to the EVM as shown in Figure 3. Set the
LOAD to constant current mode with initial value of 1.0 A. Note: if the load less than 1.0 A, the
UCC25600 may be in burst operation and the EVM output voltage may start hiccup.
6. Turn on the DC source and observe the output voltage. Its output voltage should be at nominal 12
VDC.
7. Varying the load between 1.0 A and 25 A.
3. Power Down
1. Turn off the DC source.
2. Turn off the load.
5.4 Recommended Test Setup
Figure 3. Recommended Test Set Up

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6 Test Procedure
Setup the EVM with equipment as shown in Figure 3 and following the test set up directions described in
Section 5.
6.1 Line/Load Regulation and Efficiency Measurement Procedure
Set up the load to 1.0 A and input voltage between 375 VDC and 405 VDC. Prior to turning on the power,
set up the input source current limit to 1.0 A to avoid potential damage, although the EVM has its power
limit typical 350 W. Turn on the input source. Reference test results of line and load regulation can be
found from Section 7
6.2 Output Ripple
Along with the measurement of line and load regulation, the output voltage ripple can be measured at the
same time. The method of tip-and-barrel should be used for the output voltage ripple measurement. The
EVM provides such type of test point to facilitate the measurement for the type of oscilloscopes from
Tektronix as shown in Figure 3. Reference test results of the output voltage ripple can be found in
Section 7.
6.3 Efficiency
The efficiency may be calculated based on the test data obtained from Section 6.1. To correctly measure
input and output voltage for the efficiency calculation, test points TP1 and TP2 should be used for input
voltage measurement, and test points TP10 and TP18 should be used for output voltage measurement.
Reference results of efficiency can be found in Section 7.
6.4 Bode Plots
To measure loop compensation bode plots, a sweep signal may be injected through test points TP19 and
TP21. The full system bode plots is measured with TP19 and TP21. The controller bode plots is measured
with TP21 and U3 pin 4. The modulator bode plots is measured with U3 pin4 and TP19.
6.5 Others
The EVM provides plenty of test points to facilitate the device's evaluation work. Table 2 presents a list of
test points. Users can use these test points to make measurement to the functions of their interest. The
test points are divided into two groups, namely primary side group and secondary side group. During the
measurement setup, be aware of the setup especially for different ground pick up. The EVM is designed
with 3500-V reinforced insulation between the primary and the secondary. As such there is no common
ground as reference point for the measurement to be made on both sides. In other words, each side has
its own ground to be used for measurement reference point.

65.00%
75.00%
85.00%
95.00%
1 5 10 15 20 25
Load Current A
E f f i c i e n c y
12
12.05
12.1
12.15
12.2
375 390 405
Input Voltage V
O u t p ut V o lt a ge V
12.000
12.020
12.040
12.060
12.080
12.100
12.120
12.140
1 5 10 15 20 25
Load Current A
O u tp u t V o l t a g e V
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7 Performance Data and Typical Characteristic Curves
Figure 4 through Figure 17 present typical performance curves for UCC25600EVM.
Figure 4. Line Regulation, IO= 1 A Figure 5. Load Regulation, VIN = 390 VDC
Figure 6. Typical Efficiency at VIN = 390 VDC
Figure 7. Typical Output Voltage Ripple Waveform at VIN =
390 V and IO= 15 A (TP15)

UCC25600 EVM Loop Plot (Test 2)
-60
-45
-30
-15
0
15
30
45
60
10 100 1000 10000 100000 1000000
Frequency (Hz)
G a i n (d B )
-180
-135
-90
-45
0
45
90
135
180
P h a s e ( D e g )
Gain Phase
Performance Data and Typical Characteristic Curves www.ti.com
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Figure 8. Typical Output Voltage Turn On (TP15)
Figure 9. Full System Loop Compensation (TP19 and
TP21)
Figure 10. Typical Soft-Start Waveform Figure 11. Typical Resonant Tank Current and Resonant
Capacitor Voltage