Texas Instruments UCC25230EVM-662 User manual

Using the UCC25230EVM-662
User's Guide
Literature Number: SLUU863
February 2012

User's Guide
SLUU863–February 2012
Biased Half-Bridge Converter with UCC28250
Secondary-Side Control for 48-V Telecom Applications
1 Introduction
This EVM is used to evaluate bias power supply with UCC25230 used in the UCC28250, based on a
secondary-side controlled, half-bridge DC-to-DC converter. The UCC25230EVM-662 is actually a
combination of two released EVMs, UCC28250EVM-564 and UCC25230EVM-754. The
UCC28250EVM-564 is an EVM of secondary-side controlled symmetrical half-bridge DC-to-DC converter.
The UCC25230EVM-754 is used to bias the UCC28250EVM-564 and allow for stand-alone operation in
the UCC28250EVM-564. The targeted application is telecom module design with nominal 48-V input.
UCC28250 is a PWM controller that can be used for primary-side control or secondary-side control. In this
EVM, the UCC28250 is placed at the secondary side to make secondary-side control. The UCC25230 is a
highly integrated PWM controller operating as an isolated Forward-Flyback, or Flybuck™controller. It has
integrated high-side and low-side power switches and a control circuit with all the key converter functions
included.
2 Description
The EVM is a 100-W symmetrical half-bridge DC-to-DC converter that converts 36 V to 72 V DC to a
regulated output voltage of 3.3 V and a maximum of 30-A load current. The EVM is designed in
stand-alone operation without additional external auxiliary power sources.
2.1 Typical Applications
•48-V Telecom Modular Applications With Secondary-Side Control
•Server Systems
•Datacom
•DSP’s, ASIC’s, and FPGA’s
2.2 Features
•Start Up Directly from Telecom Input Voltage 36 V to 72 V DC
•Regulated Output Voltage 3.3 V (with maximum 30-A load current)
•Smooth and Monotonic Output Voltage Turn On (with Up to 90% pre-biased output voltage)
•Output Voltage Regulation (from no load to full load, and from low line to high line)
•Primary-Side Enable ON/OFF Function and Manual Switch for Line-Under Voltage On or Off
•Secondary-Side Control
•Control-Driven Synchronous Rectifier
•Non-Latching Output Over-Voltage Protection and Hiccup Over-Current Protection
•Telecom Isolation from Primary-to-Secondary 1500 VDC
•Test Points to Facilitate the Device Evaluation
2Biased Half-Bridge Converter with UCC28250 Secondary-Side Control for 48-V SLUU863–February 2012
Telecom Applications Submit Documentation Feedback
Copyright ©2012, Texas Instruments Incorporated

www.ti.com Electrical Performance Specifications
3 Electrical Performance Specifications
Table 1. UCC25230EVM-662 Electrical Performance Specifications
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Input Characteristics
Voltage range 36 48 72 V
Maximum input current VIN = 36 V and IOUT = 30 A 3.5 A
No load input current VIN = 72 V 90 mA
Output Characteristics
Output voltage, VOUT Output current = 0 A 3.25 3.30 3.35 V
Output load current, IOUT 30 A
Output voltage ripple IOUT = 30A 50 mVpp
Output over current inception 32 A
point
Systems Characteristics
Switching frequency 200 kHz
IC clock frequency 400
Peak efficiency 91%
Full load efficiency 90%
Operating temperature Min 200 LFM forced air flow 25 ºC
3
SLUU863–February 2012 Biased Half-Bridge Converter with UCC28250 Secondary-Side Control for 48-V
Telecom Applications
Submit Documentation Feedback Copyright ©2012, Texas Instruments Incorporated

+
Schematic www.ti.com
4 Schematic
Figure 1. UCC25230EVM-662 Schematic
4Biased Half-Bridge Converter with UCC28250 Secondary-Side Control for 48-V SLUU863–February 2012
Telecom Applications Submit Documentation Feedback
Copyright ©2012, Texas Instruments Incorporated

A
B
+
_
Load
13.3V/
35A V2
+
FAN
DC
Sourc
e
_
V1
+
_
A1
J2
S1
J1 TP1 TP2
TP9 TP6
TP3
TP12
TP13
TP7 TP4
TP11
TP5
TP8
TP10
www.ti.com Test Setup
5 Test Setup
5.1 Test Equipment
Voltage Source: HP 6015A DC power supply, or equivalent to provide 36 VDC to 72 VDC, and minimum
3.5 A.
Multimeters: Fluke 45 dual display multimeter, or equivalent.
Output Load: HPA 6060A DC electronic load, or equivalent capable of 3.3 V and 30 A.
Oscilloscope: A 20-MHz or equivalent analog or digital oscilloscope.
Recommended Wire Gauge: AWG #18 for input voltage connection. AWG #16 for output load
connection.
Ventilation Fan: 200 LFM minimum compatible.
5.2 Recommended Test Setup
Figure 2. UCC25230EVM-662 Recommended Test Set Up
5
SLUU863–February 2012 Biased Half-Bridge Converter with UCC28250 Secondary-Side Control for 48-V
Telecom Applications
Submit Documentation Feedback Copyright ©2012, Texas Instruments Incorporated

Test Setup www.ti.com
5.3 List of Test Points
Table 2. Test Point Functions
TEST POINTS NAME DESCRIPTION
TP1 PGND Input voltage negative test point, for efficiency test
TP2 Vin+ Input voltage positive test point, for efficiency test
TP3 Bias_P1 Primary bias, 9V.
TP4 VOUT+ Output voltage positive test point for efficiency
TP5 VOUT- Output voltage negative test point for efficiency
TP6 Loop+ Feedback loop injection for UCC25230
TP7 Loop+ Feedback loop injection for UCC28250
TP8 Loop- Feedback loop injection for UCC28250
TP9 Loop- Primary side signal ground
TP10 Prebias+ Prebias output positive input
TP11 Vo_Ripple Output voltage ripple test
TP12 Bias_P Primary bias, 9 V
TP13 Bias_S Secondary bias, 8 V
J1 INPUT Input voltage terminals
J2 OUTPUT Output voltage terminals
6Biased Half-Bridge Converter with UCC28250 Secondary-Side Control for 48-V SLUU863–February 2012
Telecom Applications Submit Documentation Feedback
Copyright ©2012, Texas Instruments Incorporated

www.ti.com Test Procedure
6 Test Procedure
Set up the EVM based on Figure 2.
CAUTION
High voltage and high temperature present when the EVM is in operation!
6.1 Line/Load Regulation and Efficiency Measurement Procedure
1. Connect the ammeter A1 (0 A to 10 A range) between DC Source and J1 as shown in Figure 2.
2. Prior to connecting the DC source, it is advisable to limit the source current to 4 A maximum. Make
sure the DC source is initially set to 0 V and connected to J1 and A1 as shown in Figure 2.
3. Connect voltmeter, V1 across the DC source as shown in Figure 2.
4. Connect Load1 to J2 as shown in Figure 2. Set Load1 to constant current mode to sink 0 ADC before
the input voltage on J1 is applied.
5. Connect voltmeter, V2 to J2 as shown in Figure 2.
6. Turn on the ventilation fan making sure to blow air directly on the EVM.
7. Set switch S1 to position B.
8. Increase the DC source voltage from 0 V to 36.0 VDC.
9. Measure VOUT (V2), IOUT, VIN (V1) and IIN (A1).
10. Vary LOAD1 from 0 A to a higher value, up to 30 ADC.
11. Increase input voltage to a different value, up to 72 V, and repeat 9 and 10.
6.2 Equipment Shutdown
1. Decrease Load-1 to 0 A.
2. Decrease VIN to 0 V.
3. Shut down VIN and the fan.
4. Shut down the load.
7
SLUU863–February 2012 Biased Half-Bridge Converter with UCC28250 Secondary-Side Control for 48-V
Telecom Applications
Submit Documentation Feedback Copyright ©2012, Texas Instruments Incorporated

40
45
50
55
60
65
70
75
80
85
90
95
100
0 5 10 15 20 25 30
IOUT - Amps
Efficiency - %
36.0V
48.0V
72.0V
3.050
3.100
3.150
3.200
3.250
3.300
3.350
0 5 10 15 20 25 30
IOUT - Amps
VOUT - V
36.0V
48.0V
72.0V
Performance Data and Typical Characteristic Curves www.ti.com
7 Performance Data and Typical Characteristic Curves
Figure 3 through Figure 11 present typical performance curves for UCC25230EVM-662.
7.1 Efficiency
Figure 3. UCC25230EVM-662 Efficiency
7.2 Load Regulation
Figure 4. UCC25230EVM-662 Load Regulation
8Biased Half-Bridge Converter with UCC28250 Secondary-Side Control for 48-V SLUU863–February 2012
Telecom Applications Submit Documentation Feedback
Copyright ©2012, Texas Instruments Incorporated

-50.00
-40.00
-30.00
-20.00
-10.00
0.00
10.00
20.00
30.00
40.00
50.00
0.1 1.0 10.0 100.0
F - Frequency - kHz
Gain - dB
-150.00
-120.00
-90.00
-60.00
-30.00
0.00
30.00
60.00
90.00
120.00
150.00
Gain Phase
www.ti.com Performance Data and Typical Characteristic Curves
7.3 Bode Plots
Figure 5. UCC25230EVM-662 Feedback Loop Bode Plots
(VIN = 48 V, IO= 15 A)
9
SLUU863–February 2012 Biased Half-Bridge Converter with UCC28250 Secondary-Side Control for 48-V
Telecom Applications
Submit Documentation Feedback Copyright ©2012, Texas Instruments Incorporated

Performance Data and Typical Characteristic Curves www.ti.com
7.4 Turn-On Waveform
Figure 6. Output Voltage Turn On
(VIN = 48 V, IO= 15 A)
7.5 Turn-on Waveform with Pre-bias Output Voltage
Figure 7. Output Voltage Turn on with Pre bias.
(VIN = 48 V, IO= 0 A, Pre bias = 1.5 V)
10 Biased Half-Bridge Converter with UCC28250 Secondary-Side Control for 48-V SLUU863–February 2012
Telecom Applications Submit Documentation Feedback
Copyright ©2012, Texas Instruments Incorporated