1
DEMO MANUAL DC2989A
Rev. 0
DESCRIPTION
LTM4657 20Vin, 8A Step-Down
µModule
®
Regulator
Demonstration circuit 2989A features the LTM4657
µModule
®
regulator, a high performance, high efficiency
step-down regulator. The LT C
®
4657 is a complete DC/DC
point-of-load regulator in a thermally enhanced 6.25mm
x 6.25mm x 3.87mm BGA package. The LTM4657 has
an operating input voltage range of 3.1V to 20V and pro-
vides an output current up to 8A. The output voltage is
programmable from 0.6V to 5.5V and can be remotely
sensed. The stacked inductor design improves thermal
dissipation and significantly reduces the package area.
All registered trademarks and trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
BOARD PHOTO
Output voltage tracking is available through the TRACK/
SS pin for supply rail sequencing. External clock syn-
chronization is available through the SYNC/MODE pin.
For high efficiency at low load currents, select DCM mode
operation using the MODE jumper (JP7) in less noise
sensitive applications. The LTM4657 data sheet must be
read in conjunction with this demo manual for working
on or modifying DC2989A.
Design files for this circuit board are available.
Specifications are at TA = 25°C
PARAMETER CONDITIONS VALUE
Input Voltage Range 3.1V – 20V
Output Voltage VOUT Jumper selectable 1VDC, 1.5VDC, 2.5VDC, 3.3VDC, 5VDC
Maximum Continuous Output Current Derating is necessary for certain operating
conditions. See datasheet for details
8ADC
Default Operating Frequency 500kHz
Efficiency VIN = 12V, VOUT = 1.5V, IOUT = 8A 88.3%
2
DEMO MANUAL DC2989A
Rev. 0
QUICK START PROCEDURE
Demonstration circuit 2989A is an easy way to evaluate
the performance of the LTM4657. Please refer to Figure1
for test setup connections and follow the procedure below.
1. With power off, place the jumpers in the following
positions:
JUMPER POSITION FUNCTION
JP8 JP7 JP6
RUN MODE VOUT SELECT
ON CCM 1.5V
2. Before connecting input supply, load and meters, pre-
set the input voltage supply to be between 3.1V to 20V.
Preset the load current to 0A.
3. With power off, connect the load, input voltage supply
and meters as shown in Figure1.
4. Turn on input power supply. The output voltage meters
for each phase should display the programmed output
voltage ± 2%.
5. Once the proper output voltage is established, adjust
the load current within the 0-8A range and observe
the load regulation, efficiency, and other parameters.
Output voltage ripple should be measured across the
furthest output cap with a BNC cable and oscilloscope
from J2.
6. To observe increased light load efficiency, place the
MODE pin jumper (JP7) in the DCM position.
7. For optional load transient testing, an on-board
transient circuit is provided to measure tran-sient
response. Place a positive pulse signal between the
IO_STEP_CLK pin and GND pins. The pulse amplitude
sets the load step current amplitude. The pulse width
should be short (<1ms) and pulse duty cycle should
be low (<15%) to limit the thermal stress on the load
transient circuit. The load step response can be moni-
tored with a BNC connected to J1 (5mV/A).
4
DEMO MANUAL DC2989A
Rev. 0
QUICK START PROCEDURE
3.3V
OUT
, 1MHz
2.5V
OUT
, 800kHz
1.5V
OUT
, 650kHz
1V
OUT
, 500kHz
LOAD CURRENT (A)
0
1
2
3
4
5
6
7
8
70
75
80
85
90
95
100
EFFICIENCY (%)
5V
OUT
, 1.25MHz
3.3V
OUT
, 1MHz
2.5V
OUT
, 800kHz
1.5V
OUT
, 650kHz
1V
OUT
, 500kHz
LOAD CURRENT (A)
0
1
2
3
4
5
6
7
8
65
70
75
80
85
90
95
EFFICIENCY (%)
Figure2. Measured Supply Efficiency at 5VIN and 12VIN
6
DEMO MANUAL DC2989A
Rev. 0
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 2 C1, C6 CAP, 2.2uF, X7R, 10V, 20%, 0603 TDK, C1608X7R1A225M080AC
2 3 C2, C13, C29 CAP, 22uF, X5R, 25V, 10%, 1206 AVX, 12063D226KAT2A
3 1 C4 CAP, 1uF, X7R, 25V, 10%, 0603 TAIYO YUDEN, TMK107B7105KA-T
4 2 C5, CB17 CAP, 100uF, X5R, 10V, 20%, 1206 TDK, C3216X5R1A107M160AC
5 1 C7 CAP, 0.1uF, X7R, 25V, 10%, 0603 AVX, 06033C104KAT2A
6 1 C8 CAP, 100pF, X7R, 25V, 5%, 0603 AVX, 06033C101JAT2A
7 1 C9 CAP, 470pF, X7R, 50V, 10%, 0603 AVX, 06035C471KAT2A
8 1 C10 CAP, 220uF, ALUM. ELECT., 35V SUN ELEC, 35HVH220M
9 1 C11 CAP, 100uF, X5R, 10V, 20%, 1210 KEMET, C1210C107M8PACTU
10 1 C18 CAP, 1uF, X7R, 10V, 20%, 0603 AVX, 0603ZC105MAT2A
11 1 Q1 XSTR, MOSFET, N-CH, 40V, TO-252 (DPAK) VISHAY, SUD50N04-8M8P-4GE3
12 1 R3 RES, 10k OHMS, 1%, 1/10W, 0603, AEC-Q200 VISHAY, CRCW060310K0FKEA
13 1 R4 RES, 60.4k OHMS, 1%, 1/10W, 0603, AEC-Q200 VISHAY, CRCW060360K4FKEA
14 1 R6 RES, 30.1k OHMS, 1%, 1/10W, 0603, AEC-Q200 VISHAY, CRCW060330K1FKEA
15 1 R7 RES, 150k OHMS, 5%, 1/10W, 0603, AEC-Q200 PANASONIC, ERJ3GEYJ154V
16 2 R8, R16 RES, 100k OHMS, 1%, 1/10W, 0603 STACKPOLE, RMCF0603FG100K
17 2 R9, R10 RES, 10 OHMS, 1%, 1/10W, 0603 VISHAY, CRCW060310R0FKEA
18 1 R14 RES, 10.7k OHMS, 1%, 1/10W, 0603 NIC, NRC06F1072TRF
19 1 R15 RES, 15k OHMS, 1%, 1/10W, 0603, AEC-Q200 VISHAY, CRCW060315K0FKEA
20 1 R17 RES, 0 OHM, 1/10W, 0603, AEC-Q200 VISHAY, CRCW06030000Z0EA
21 1 R21 RES, 6.65k OHMS, 1%, 1/10W, 0603 NIC, NRC06F6651TRF
22 1 RS2 RES, 0.005 OHM, 1%, 1W, 2512 VISHAY, WSL25125L000FEA
23 1 U1 IC, Step-Down uModule Reg, BGA-49 ANALOG DEVICES, LTM4657EY#PBF
Additional Demo Board Circuit Components
1 0 C3, C12, C14, C16, C21, C30 CAP, OPTION, 1206 N/A
2 0 C15, C19 CAP, OPTION, 0603 N/A
3 0 C20, CA17 CAP, OPTION, 7343 N/A
4 0 C22-C24 CAP, OPTION, 0805 N/A
5 0 C25-C28 CAP, OPTION, 1210 N/A
6 0 L1 IND, OPTION, 1812 N/A
7 0 L2 IND, OPTION, COILCRAFT XAL7070 N/A
8 0 R1, R2, R5, R11-R13, R19, R20 RES, OPTION, 0603 N/A
Hardware: For Demo Board Only
1 7 E1, E3, E5, E8-E10, E12 TEST POINT, TURRET, 0.064 MILL-MAX, 2308-2-00-80-00-00-07-0
2 4 E2, E4, E7, E13 BANANA JACK, FEMALE KEYSTONE, 575-4
3 2 E6, E11 TEST POINT, TURRET, 0.094 MILL-MAX, 2501-2-00-80-00-00-07-0
4 2 J1, J2 CONN, BNC, 5-PIN AMPHENOL RF, 112404
5 6 JP1-JP6 HEADER, 1x2, 2mm SULLINS, NRPN021PAEN-RC
6 1 JP7 HEADER, 2x3, 2mm SULLINS, NRPN032PAEN-RC
7 1 JP8 HEADER, 1x3, 2mm SAMTEC, TMM-103-02-L-S
8 4 MP1-MP4 STANDOFF, NYLON, SNAP-ON, 0.50 KEYSTONE, 8833
9 3 XJP1, XJP7, XJP8 CONN, SHUNT, FEMALE, 2-POS, 2mm SAMTEC, 2SN-BK-G
7
DEMO MANUAL DC2989A
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog
Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications
subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
SCHEMATIC DIAGRAM
8
DEMO MANUAL DC2989A
Rev. 0
ANALOG DEVICES, INC. 2020
02/20
www.analog.com
ESD Caution
ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection
circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.
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