DC721A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B
6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
LTC3738CUHF and LTC3731CUH
DESCRIPTION
Demonstration circuits 721A-A and 721A-B are high current step-down converters for Intel VRM/VRD10 and
VRM9 processor power applications. The demo circuits
feature the current-mode PolyPhaseTM controllers
LTC3738CUHF and LTC3731CUH. The input voltage is
from 8V to 14V and the output voltage is controlled by
the VID setting. DC721A-A is a 6-phase LTC3738 and
LTC3731 supply that can provide up to 120A output current. DC721A-B is a single LTC3738 3-phase 65A output
supply. Both LTC3738CUHF and LTC3731CUH controllers are in the QFN packages to minimize the supply
footprint size and improve the thermal performance.
The LTC3738 controller has 6 VID pins to program the
output voltage according to Intel VRM9 or VRM/VRD10
requirement. Accurate active voltage positioning (AVP)
is implemented with LTC3738 to meet Intel’s tight load
line regulation requirement. Optional 0.1% external voltage reference and external Op-Amp compensation circuits are also available on DC721A-A and DC721A-B for
applications requiring <0.5% output voltage regulation
accuracy and optimum transient response.
Design files for this circuit board are available. Call
the LTC factory.
LTC, PolyPhase are trademarks of Linear Technology Corporation
Table 1. Performance Summary (TA = 25°C)
PARAMETER
TEST CONDITION
VALUE
Minimum Input Voltage
8V
Maximum Input Voltage
14V
Controlled by VID setting:
Output Voltage VOUT
Meet Intel VRM9 and VRM/VRD10
static and transient specifications
VRM9: 1.100V-1.850V, 25mV VID step
VRM/VRD10: 0.8375V-1.6000V, 12.5mV VID step
DC721A-A, 6-phase LTC3738+3731 design
120 ADC
DC721A-B, 3-phase LTC3738 design
65 ADC
DC721A-A, VIN = 12V, VOUT=1.5VVID, IOUT = 120A
87.6% Typical, See Figure 1
DC721A-B, VIN = 12V, VOUT=1.5VVID, IOUT = 65A
87.6% Typical
Output Voltage Load Line
DC721A-A, VIN = 12V, VOUT=1.35VVID
See Figure 2
Output Load Transient Response
DC721A-A, VIN = 12V, VOUT=1.5VVID
See Figure 3
Maximum Continuous Output Current
Efficiency
QUICK START PROCEDURE
Demonstration circuits 721A-A and 721A-B are easy to
set up to evaluate the performance of the LTC3738CUHF
and LTC3731CUH. Refer to Figure 4 for proper measurement equipment setup and follow the procedure below:
1.
+5V
Select
INT
5V
DLC BIAS
DLC
VRM
SELECT
INT
ON
OFF
OFF
VRM10
Place jumpers in the following positions:
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QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B
6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
2.
With power off, connect the input power supply to Vin
and GND. Connect an active load to VOUT+ and VOUT-.
Preset the load to 0A.
3.
Set the VID dip-switch S1 as follows:
B4
B3
B2
B1
B0
B5
0
1
1
1
0
1
NOTE: Make
sure that the input voltage does not ex-
ceed 14V.
4.
5.
Once the proper output voltages are established, adjust the loads within the operating range and observe
the output voltage regulation, ripple voltage, efficiency
and other parameters. With above VID setting, the
output voltage should be within 1.391V-1.441V at
65A load current.
NOTE: The
maximum current of DC721A-A is 120A
and DC721A-B is 65A. A cooling fan is needed to limit
board temperature rise if output current is higher than
50A for DC721A-B or 90A for DC721A-A.
Turn on the power at the input. Check for the proper
output voltages. With above VID setting, the output
voltage should be within 1.450V-1.500V at 0A load.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B
6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
Efficiency vs. Load Current
95.00%
85.00%
Efficiency (%)
75.00%
65.00%
VOUT
55.00%
DC721A, 6-phase 120A design
Vin=12V, Vo=1.5V, Io(max)=120A
45.00%
VCore_max
VCore_min
35.00%
25.00%
0
20
40
60
80
Load Current (A)
100
120
Figure 1. Measured efficiency vs. load current
Figure 2. Output load line meets Intel VRD10 spec
Figure 3 Load transient @ 12VIN, 1.5VO of DC721A-A
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QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B
Iout
V
Current Shunt
Load
0-120A
6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
Optional
5V bias
Current Shunt
V
Vout
V
Iin
V
Vin
Figure 4. Test Setup of DC721A-A and DC721A-B
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QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B
6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
DC721A-A – 6 Phase 120A
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QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B
6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
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6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
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6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
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QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B
6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
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QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B
6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
DC721A-B – 3 Phase 65A
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QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B
6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
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6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
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6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY
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