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DESCRIPTION
Demonstration circuit 1626A is a dual output 1.5V/15A
and 1.2V/15A synchronous buck converter operating with
a switching frequency of 300kHz over an input voltage
range of 4.5V to 26V. The demo board comes in two ver-
sions. The -A version uses inductor DCR current sensing
with an iron powder inductor for high efficiency. The -B
version uses a 2.5mΩ sense resistor for accurate current
sensing with a low DCR ferrite inductor. The fixed on-time
valley current mode architecture of the LTC3838 allows for
a fast load step response (see Figures 6 to 9). The load
step response can be tested with the on-board load step
circuit and a bench pulse generator.
The demo board uses a high density, two sided drop-in
layout. The entire converter, excluding the bulk output and
input capacitors, fits within a compact 1.5" × 1.0" area
on the board. The package style for the LTC3838EFE is a
38-lead TSSOP with an exposed ground pad.
PERFORMANCE SUMMARY
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
Output Voltage V
OUT1
Output Voltage V
OUT2
V
Maximum Output Current, I
OUT1
V
Maximum Output Current, I
OUT2
Nominal Switching Frequency
-A Efficiency
See Figures 2 and 3
-B Efficiency
See Figures 4 and 5
Wide Input Range, High Efficiency
(T
= 25°C)
A
OUT1
OUT2
DEMO MANUAL DC1626A
Step-Down DC/DC Converter
The main features of the board are listed below:
• MODE jumper to program either DCM or FCM at light
or no load
• EXTVCC pin
• PLLIN pin to synchronize the converter to an external
clock
• Remote sensing for V
• Optional resistors to tie the two phases together
• Each rail has its own RUN pin, PGOOD pin and
TRACK/SS pin
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, μModule, Linear Technology and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
CONDITION
I
= 0A to 15A, V
= 4.5V to 26V
OUT1
IN
I
= 0A to 15A, V
= 4.5V to 26V
OUT2
IN
V
= 4.5V to 26V, V
= 1.2V
IN
OUT1
V
= 4.5V to 26V, V
= 1.5V
IN
OUT2
V
= 1.2V, I
= 15A, V
= 12V
OUT1
OUT1
IN
V
= 1.5V, I
= 15A, V
= 12V
OUT2
OUT2
IN
V
= 1.2V, I
= 15A, V
= 12V
OUT1
OUT1
IN
V
= 1.5V, I
= 15A, V
= 12V
OUT2
OUT2
IN
LTC3838EFE
OUT1
VALUE
4.5V
26V
1.2V ±2%
1.5V ±2%
15A
15A
300kHz
89.1% Typical
90.2% Typical
85.9%
88.2%
dc1626afa
1
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Related Manuals for Linear Technology DC1626A
Summary of Contents for Linear Technology DC1626A
- Page 1 1.5" × 1.0" area L, LT, LTC, LTM, μModule, Linear Technology and the Linear logo are registered trademarks of on the board. The package style for the LTC3838EFE is a Linear Technology Corporation. All other trademarks are the property of their respective owners.
-
Page 2: Quick Start Procedure
DEMO MANUAL DC1626A QUICK START PROCEDURE Demonstration circuit 1626A is easy to set up to evalu- Load Step Transient Testing ate the performance of the LTC3838EFE. Please refer to Demonstration circuit 1626A provides a simple load step Figure 1 for proper measurement equipment setup and circuit consisting of a MOSFET and sense resistor for each follow the procedure below. - Page 3 DEMO MANUAL DC1626A QUICK START PROCEDURE Single Output/Dual Phase Operation • Tie VFB2 to INTVCC by stuffing 0Ω at R1. This will disable the error amp for phase 2 and internally tie the A single output/dual phase converter may be preferred for two ITH signals together.
- Page 4 DCR = 1.7mΩ TYP , 1.8mΩ MAX DCR = 1.7mΩ TYP , 1.8mΩ MAX dc1626a F02 dc1626a F03 Figure 2. Efficiency Curves for the DC1626A-A Figure 3. Efficiency Curves for the DC1626A-A (DCR Sense) in FCM (DCR Sense) in FCM and DCM.
- Page 5 5A/DIV 5A/DIV dc1626a F06 dc1626a F07 Figure 6. Load Step Response of the 1.2V Rail on the DC1626A-A Figure 7. Load Step Response of the 1.5V Rail on the DC1626A-A (DCR Sense) at V = 12V. C = 2× Sanyo 2R5TPE330M9 || (DCR Sense) at V = 12V.
- Page 6 DEMO MANUAL DC1626A PARTS LIST 1626A-A (DCR Sense) ITEM REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components CAP , X7R 330pF 50V 0603 AVX 06035C331KAT2A C3, C16, C4, C10, C13 CAP , X5R 0.1μF 50V 0603 AVX 06035D104KAT2A C5, C14 CAP , X5R 0.01μF 25V 0603...
-
Page 7: Parts List
DEMO MANUAL DC1626A PARTS LIST 1626A-A (DCR Sense) ITEM REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Hardware/Components (For Demo Board Only) STAND-OFF STAND-OFF , NYLON 0.25" KEYSTONE 8831 (SNAP ON) E1-E12, E14-E25 TESTPOINT, TURRET 0.095" MILL-MAX 2501-2-00-80-00-00-07-0 J1-J6 JACK, BANANA KEYSTONE 575-4... - Page 8 DEMO MANUAL DC1626A PARTS LIST 1626A-B (R SENSE ITEM REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Additional Circuit Components C1, C2, C15, C17 CAP , 0603 OPTIONAL CIN6-CIN8 CAP , 1210 OPTIONAL COUT13-COUT16 CAP , 7343 OPTIONAL Q5-Q8 MOSFET, N-CHANNEL LFPAK OPTIONAL...
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Page 9: Schematic Diagram
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. - Page 10 Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions: This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods.
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