Linear Technology DC2312A-A, DC2312A-B Demo Manual

DESCRIPTION

DEMO MANUAL

DC2312A-A/DC2312A-B

LTC3882EUJ-1 High Efficiency

Step-Down DC/DC Converter

with Power System Management

Demonstration circuit 2312A is a high current, high
efficiency, dual phase synchronous buck converter
featuring the LTC3882EUJ-1, a dual output voltage
mode controller with the additional features of dif
ferential V

sense and dedicated PGOOD output on

OUT

both channels, compared to LTC3882. The LTC3882-1
has the PMBus interface and power system manage
ment functions.

There are two versions of the boards available:

n

DC2312A-A: Dual phase dual output configuration. De-

V

fault output setting

n

DC2312A-B: Dual phase single output configuration.
Default output setting V

= 1.5V/35A, V

OUT0

OUT0

= 1.0V/70A.

= 1.0V/35A.

OUT1

The DC2312A powers up to default settings and pro­duces power

based

on configuration resistors or with
its nonvolatile memory without the need for any serial
bus communication. This allows easy evaluation of the

DC/DC converter. To fully explore the extensive power
system management features of the part, download the
GUI software LTpowerPlay™ onto your PC and use LT C’s

2

-

C/SMBus/PMBus Dongle DC1613A to connect to the

I
board. LTpowerPlay allows the user to reconfigure the
part on-the-fly and store the configuration settings within

-

its onboard EEPROM, along with viewing telemetry pa
rameters that include

voltage, current, temperature and

fault status.

GUI Software LTpowerPlay Download

The software can be downloaded from:

http://www.linear.com/LTpowerPlay

Design files for this circuit board are available at

http://www.linear.com/demo/DC2312A

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
LTpowerPlay is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.

-

PERFORMANCE SUMMARY

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IN

V

OUT0

I

OUT0

V

OUT1

I

OUT1

V

OUT0

I

OUT0

F

SW

F

SW

EFFICIENCY Full Load Efficiency (-A Version) V

*Note: The DC2312A uses 2.5V-rated low ESR PosCAP (Part No. 2R5TPE470M7) as output capacitors for optimized load transient performance.
If > 2.0V V

**Note: When continuously running at full load, forced air flow is needed.

Input Supply Range 7 12 14 V

Output Voltage Range (-A Version) I

Output Current Range (-A Version) 0 35** A

Output Voltage Range (-A Version) I

Output Current Range (-A Version) 0 35** A

Output Voltage Range (-B Version) I

Output Current Range (-B Version) 0 70** A

Factory Default Switching (-A Version) 500 kHz

Factory Default Switching (-B Version) 450 kHz

Full Load Efficiency (-B Version) V

is needed, 4V or 6.3V-rated output capacitors should be used.

OUT

Specifications are at TA = 25°C

= 0A to 35A, VIN = 7V to 14V 0.5 1.5 2.0* V

OUT0

= 0A to 35A, VIN = 7V to 14V 0.5 1.0 2.0* V

OUT1

= 0A to 70A, VIN = 7V to 14V 0.5 1.0 2.0* V

OUT0

V

OUT0

OUT1

OUT0

= 1.5V, I

= 1.0V, I

= 1.0V, I

= 35A, See Figure 5 90.6 %

OUT0

= 35A, See Figure 5 88.0 %

OUT1

= 70A, See Figure 6 87.8 %

OUT0

dc2312afb

1

DEMO MANUAL

DC2312A F01

DC2312A-A/DC2312A-B

QUICK START PROCEDURE

Demonstration circuit 2312A makes it easy to set up to
evaluate the performance of the LTC3882-1. Refer to
Figures 2 and 3 for proper measurement equipment setup
and follow the procedure below.

NOTE. When measuring the input or output voltage ripple,
care must be taken to avoid a long ground lead on the
oscilloscope probe. Measure the output voltage ripple by
touching the probe tip directly across the C13 or C39. See
Figure 4 for proper scope probe technique.

1. Make sure jumpers are in the following positions:

DC2312A-A Version

JUMPER POSITION FUNCTION

JP1 NC Untie GPIO0B to GPIO1B

JP2 NC Untie RUN0 to RUN1

JP4 ON External 5V VDR for DrMOS

JP6 ON External 5V V

DC2312A-B Version

JUMPER POSITION FUNCTION

JP1 C Tie GPIO0B to GPIO1B

JP2 C Tie RUN0 to RUN1

JP4 ON External 5V VDR for DrMOS

JP6 ON External 5V V

for LTC3882-1

CC

for LTC3882-1

CC

2. With power off, connect the input power supply to VIN
and GND. Connect active load to the output.

3. Make sure both RUN switches are OFF.

4. Turn on the power at the input.

Note. Make sure that the input voltage does not ex

-

ceed15V.

Turn on RUN switches as desired.

5.

+

6. Check for the correct output voltage from V
V

OUT0

–

and from V

OUT1

+

to V

OUT1

–

.

OUT0

to

Note. If there is no output, temporarily disconnect the

load to make sure that the load is not set too high.

7. Once the proper output voltage is established, adjust
the loads within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.

8. Connect the dongle and control the output voltages
from the GUI. See LTpowerPlay Quick Start Procedure
session for details.

CONNECTING A PC TO DC2312A

You can use a PC to reconfigure the power management
features of the LTC3882-1 such as: nominal V
set points, OV/UV limits, temperature fault limits, sequenc-

,

ing parameters

the fault log, fault responses, GPIO and

USB CABLE

USB TO I2C/PMBUS

DONGLE DC1613A

2

other functionality. The DC1613A dongle may be plugged

, margin

OUT

in regardless of whether or not V
be hot plugged.

+12V

POWER SUPPLY

V

IN

12-PIN

CONNECTOR

Figure1. Demo Setup with PC

LTC3882-1

DEMO BOARD

DC2312A

V

V

OUT0

OUT1

LOAD

LOAD

is present. Dongle can

IN

dc2312afb

QUICK START PROCEDURE

+

–

+

–

DEMO MANUAL

DC2312A-A/DC2312A-B

–

I

OUT0

+

A

I

IN

+

–

+

POWER

V

IN

SUPPLY

–

SHUNT

V

OUT0

LOAD

V

OUT0

+

–

DC1613A
CONNECTOR

V

OUT1

I

OUT1

LOAD

SHUNT

Figure2. Power Test Setup for DC2312A-A

+

–

V

OUT1

DC2312A F02

dc2312afb

3

DEMO MANUAL

+

–

+

–

DC2312A-A/DC2312A-B

QUICK START PROCEDURE

–

I

OUT0_1

+

A

I

IN

+

–

+

POWER

V

IN

SUPPLY

–

SHUNT

V

OUT0

LOAD 1

V

OUT0

+

–

FOR BETTER THERMAL DISTRIBUTION,
USE A PIECE OF LOW IMPEDANCE METAL
TO CONNECT TOP LAYER V
AND PULL CURRENT EVENLY FROM J3
TO J4 AND FROM J9 TO J8.

DC1613A
CONNECTOR

OUT

COPPER

V

OUT0

I

OUT0_2

LOAD 2

SHUNT

Figure3. Power Test Setup for DC2312A-B

DC2312A F03

4

dc2312afb

QUICK START PROCEDURE

LOAD CURRENT (A)

051015202530

35

65707580859095

EFFICIENCY (%)

DC2312A F05

LOAD CURRENT (A)

0102030405060

7065707580

859095

EFFICIENCY (%)

DC2312A F06

DEMO MANUAL

DC2312A-A/DC2312A-B

COMBINING DC2312A WITH OTHER DIGITAL POWER
DEMO BOARDS

The DC2312A may be plugged together in a multi-board
array with other LT C power system management boards
using J12 and J13.

MEASURING OUTPUT RIPPLE VOLTAGE

An accurate ripple measurement may be performed by
using the configuration in Figure 4 across C13 or C39.

+ –

C

OUT

MEASURING EFFICIENCY (SEE FIGURES 5 AND 6)

To accurately measure efficiency of any configuration, do
the following:

n

Set JP4 and JP6 on the “OFF” position.

n

Connect external 5V supply to VDR and VCC turrets and
measure its input current.

n

Measure VIN across the input ceramic capacitor (C10,
C6). Measure V

across the output ceramic capaci-

OUT

tor (C13, C39).

n

Add the loss from external 5V supply into the efficiency
calculation.

Figure4. Measuring Output Voltage Ripple

V

= 1.5V

OUT0

= 1.0V

V

OUT1

Figure5. DC2312A-A, Typical Efficiency Curves,
VIN = 12V, FSW = 500kHz, CCM

V

OUT

GND

V

OUT0

= 1.0V

Figure6. DC2312A-B, Typical Efficiency Curves,
V

= 12V, FSW = 450kHz, CCM

IN

dc2312afb

5

DEMO MANUAL
DC2312A-A/DC2312A-B

QUICK START PROCEDURE

Figure7. Load Transient Waveform DC2312A-A, VIN = 12V, V

Figure8. Load Transient Waveform DC2312A-A, V

= 12V, V

IN

= 1.5V, FSW = 500kHz, 0% to 25% (8.75A) Load Step

OUT0

= 1.0V, FSW = 500kHz, 0% to 25% (8.75A) Load Step

OUT1

Figure9. Load Transient Waveform DC2312A-B, V

6

= 12V, V

IN

= 1.0V, FSW = 450kHz, 0% to 25% (17.5A) Load Step

OUT0

dc2312afb

QUICK START PROCEDURE

DEMO MANUAL

DC2312A-A/DC2312A-B

Figure 10. Thermal Picture of DC2312A-A, VIN = 12V, V

Figure 11. Thermal Picture of DC2312A-B, V

= 1.5V/35A, V

OUT0

= 12V, V

IN

= 1.0V/35A, fSW = 500kHz, 400LFM Air Flow

OUT1

= 1.0V/70A, fSW = 450kHz, 400LFM Air Flow

OUT0

dc2312afb

7