Analog Devices DC2958A Quick setup guide

1
DEMO MANUAL DC2958A
Rev. 0
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Voltage Range 42 V
VOUT Output Voltage DC2958A-A/DC2958A-B 4.8 5 5.2 V
DC2958A-C 3.168 3.3 3.432
IOUT Maximum Output Current 3 A
fSW Switching Frequency 1.85 2 2.15 MHz
EFF Efficiency for DC2958A-A/DC2958A-B VIN = 12V, IOUT = 1A 92.1 %
Efficiency for DC2958A-C VIN = 12V, IOUT = 1A 89.3 %
DESCRIPTION
LT8609A/09A-5/09A-3.3
42V, 3A Micropower Synchronous
Step-Down Regulator
Demonstration circuit 2958A is a 42V, 3A micro-
power synchronous step-down regulator featuring the
LT
®
8609A/09A-5/09A-3.3. There are three assembly ver-
sions; DC2958A-A is for the LT8609A adjustable output,
DC2958A-B is for the LT8609A-5 with a fixed 5V output
voltage and DC2958A-C is for the LT8609A-3.3 with a
fixed 3.3V output voltage.
The LT8609A/09A-5/09A-3.3 is a compact, high efficiency,
high speed synchronous monolithic step-down switching
regulator that consumes only 2.5μA of quiescent current.
Top and bottom power switches, compensation compo-
nents and other necessary circuits are inside of the IC to
minimize external components and simplify design.
The SYNC pin on the demo board is grounded by default
for low ripple Burst Mode operation. Moving JP1 to
PULSE SKIPPING position changes the operation mode to
pulse-skipping operation. Once JP1 is placed on SPREAD
SPECTRUM position, VCC is applied to the SYNC pin for
low EMI spread spectrum operation. To synchronous to
an external clock, move JP1 to SYNC and apply the exter-
nal clock to the SYNC turret.
The demo board is designed for 5V or 3.3V output with
up to 42V input. The wide input range allows a variety of
input sources, such as automotive batteries and industrial
supplies. The minimum input voltage can be as low as 3V
All registered trademarks and trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
for drop out mode operation. Under this mode, the output
voltage is below the regulation point and follow the input
voltage. To maintain the output under regulation, input
voltage should be above certain value. For DC2958A-A
(adjustable) and DC2958A-B (5V), this value is 5.5V
while 3.8V for DC2958A-C (3.3V). The rated maximum
load current is 3A, while derating is necessary for certain
input voltage and thermal conditions. Figure1 shows the
efficiency of the circuit. Figure2 shows the IC top tem-
perature rising on DC2958A demo board under different
load conditions.
The demo board has an EMI filter installed. The radiated
EMI performances of the board (with EMI filter) are shown
in Figure3 and Figure4. The red lines in Figure3 and
Figure4 are CISPR25 Class 5 peak limit. To use the EMI
filter, the input should be tied to VEMI, not VIN. An inductor
L2, which is shorted on the board by default, can be added
in the EMI filter to further reduce the conducted emission.
The LT8609A/09A-5/09A-3.3 data sheet gives a complete
description of the part, operation and application informa-
tion. The data sheet must be read in conjunction with this
demo manual for DC2958A.
Design files for this circuit board are available.
Specifications are at TA= 25°C

2
DEMO MANUAL DC2958A
Rev. 0
Figure1. Efficiency vs Load Current at 12V Input 2MHz Switching Frequency
Figure2. LT8609A Demo Circuit Case Temperature Rise
QUICK START PROCEDURE
V
IN
= 12V
LT8609A-5
LT8609A-3.3
LOAD CURRENT (A)
0
0.5
1
1.5
2
2.5
3
50
60
70
80
90
100
EFFICIENCY (%)
DC2958 F01
LT8609A-5 12VIN
LT8609A-3.3 12VIN
LT8609A-5 24VIN
LT8609A-3.3 24VIN
LOAD CURRENT (A)
0
0.5
1
1.5
2
2.5
3
0
10
20
30
40
50
60
70
80
90
100
TRISE (°C)
DC2958A F02

3
DEMO MANUAL DC2958A
Rev. 0
Figure3. LT8609A-5 Demo Circuit EMI Performance in CISPR25 Radiated Emission Test,
(VIN = 14V, VOUT = 5V, IOUT = 2A, 2MHz Switching Frequency)
Figure4. LT8609A-3.3 Demo Circuit EMI Performance in CISPR25 Radiated Emission Test,
(VIN = 14V, VOUT = 3.3V, IOUT = 2A, 2MHz Switching Frequency)
DC2958A–A/ DC2958A–B DEMO BOARD
(WITH EMI FILTER INSTALLED)
14V INPUT TO 5V OUTPUT AT 2A, f
SW
= 2MHz
CLASS 5 PEAK LIMIT
SPREAD SPECTRUM MODE
FIXED FREQUENCY
FREQUENCY (MHz)
0
100
200
300
400
500
600
700
800
900
1000
–20
–10
0
10
20
30
40
50
60
AMPLITUDE (dBµV/m)
(CISPR25 Radiated Emission Test with Class 5 Peak Limits)
DC2958 F03
DC2958A–C DEMO BOARD
(WITH EMI FILTER INSTALLED)
14V INPUT TO 3.3V OUTPUT AT 2A, f
SW
= 2MHz
CLASS 5 PEAK LIMIT
SPREAD SPECTRUM MODE
FIXED FREQUENCY
FREQUENCY (MHz)
0
100
200
300
400
500
600
700
800
900
1000
–20
–10
0
10
20
30
40
50
60
AMPLITUDE (dBµV/m)
(CISPR25 Radiated Emission Test with Class 5 Peak Limits)
DC2958 F04
QUICK START PROCEDURE

4
DEMO MANUAL DC2958A
Rev. 0
DC2958A is easy to set up to evaluate the performance of
the LT8609A/09A-5/LT8609A/09A-3.3. Refer to Figure5
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. See Figure6 for the proper
scope technique.
1. Set an input power supply that is capable of 42V/3A.
Then turn off the supply.
2. With power off, connect the supply to the input termi-
nals VIN and GND.
3. Turn on the power at the input.
NOTE:Make sure that the input voltage never
exceeds42V.
4. Check for the proper output voltage. Turn off the power
at the input.
5. Once the proper output voltage is established, connect
a variable load capable of sinking 3A to the output ter-
minals VOUT and GND. Set the current for 0A.
a. If efficiency measurements are desired, an amme-
ter can be put in series with the output load in order
to measure the DC2958A’s output current.
b. A voltmeter can be placed across the output ter-
minals in order to get an accurate output voltage
measurement.
6. Turn on the power at the input.
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 again established,
adjust the load and/or input within the operating range
and observe the output voltage regulation, ripple volt-
age, efficiency and other desired parameters.
8. An external clock can be added to the SYNC termi-
nal when SYNC function is used (JP1 on the SYNC
position). Please ensure that the chosen RT sets the
LT8609A/09A-5/09A-3.3 switching frequency to equal
or below the lowest SYNC frequency. See the data
sheet section, “Synchronization.”
QUICK START PROCEDURE

5
DEMO MANUAL DC2958A
Rev. 0
Figure5. Proper Measurement Equipment Setup
V
OUT
GND
Figure6. Measuring Output Ripple
QUICK START PROCEDURE

6
DEMO MANUAL DC2958A
Rev. 0
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C2 CAP., X7R, 4.7μF, 50V, 10% 1206 MURATA, GRM31CR71H475K
2 1 C4 CAP., X7R, 0.1μF, 16V, 10%, 0603 MURATA, GRM188R71C104KA01D
4 1 C6 CAP., X7R, 47μF, 10V, 10%, 1210 MURATA, GRM32ER71A476KE20L
5 1 C7 CAP., X7R, 1.0μF, 25V, 10%, 0603 MURATA, GRM188R71E105KA12D
6 1 C8 CAP., X7R, 0.01μF, 16V, 10%, 0603 AVX, 0603YC103KAT2A
7 1 L1 IND., 2.2µH COILCRAFT, XFL4020-222MEC
8 1 R2 RES., CHIP, 18.2k, 1/10W, 1%, 0603 VISHAY, CRCW060318K2FKEA
9 1 R3 RES., CHIP, 49.9k, 1/10W, 1%, 0603 VISHAY, CRCW060349K9FKEA
DC2958A-A Version Specific Components
1 1 U1 IC, REGULATOR, DDM-10 ANALOG DEVICES, LT8609AEDDM#PBF
2 1 C5 CAP., C0G, 10pF, 25V, 5%, 0603 AVX, 06033A100JAT2A
3 1 R4 RES., CHIP, 1MΩ, 1/10W, 1%, 0603 VISHAY, CRCW06031M00FKEA
4 1 R5 RES., CHIP, 187k, 1/10W, 1%, 0603 VISHAY, CRCW0603187KFKEA
DC2958A-B Version Specific Components
1 1 U1 IC, REGULATOR, DDM-10 ANALOG DEVICES, LT8609AEDDM-5#PBF
2 0 C5 (OPT.) CAP., 0603
3 1 R4 RES., 0Ω, 1/10W, 0603 VISHAY, CRCW06030000Z0EA
4 0 R5 (OPT.) RES., 0603
DC2958A-C Version Specific Components
1 1 U1 IC, REGULATOR, DDM-10 ANALOG DEVICES, LT8609AEDDM-3.3#PBF
2 0 C5 (OPT.) CAP., 0603
3 1 R4 RES., 0Ω, 1/10W, 0603 VISHAY, CRCW06030000Z0EA
4 0 R5 (OPT.) RES., 0603
Additional Demo Board Circuit Components
1 1 C1 CAP., ALUM 22μF 63V SUN ELECT, 63CE22BS
2 2 C3,C10 CAP., X7R, 4.7μF, 50V, 10% 1206 MURATA, GRM31CR71H475K
3 1 C9 CAP., X7R, 4.7μF, 16V, 10%, 0805 MURATA, GRM21BR71C475K73L
4 1 C11 CAP., X7R, 1μF, 50V, 10%, 0805 TDK, C2012X7R1H105K
5 2 C12, C13 CAP., X7R, 0.1μF, 50V, 10%, 0603 MURATA, GRM188R71H104KA93D
6 1 FB1 FERRITE BEAD 0805 TDK, MPZ2012S221A
7 1 L2 RES., CHIP, 0Ω, 3/4W, 2010 VISHAY, CRCW20100000Z0EF
8 1 R1 RES., CHIP, 1MΩ, 1/10W, 1%, 0603 VISHAY, CRCW06031M00FKEA
9 0 R6 (OPT.) RES., 0603
Hardware for Demo Board Only
1 9 E1 – E9 TESTPOINT, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0
2 1 E10(OPT.) TESTPOINT, TURRET, 0.094"
3 1 JP1 DOUBLE ROW HEADER 2 × 4 0.079" SULLINS NRPN042PAEN-RC
4 1 XJP1 SHUNT, 0.079" CENTER SAMTEC 2SN-BK-G
5 4 MH1 – MH4 STAND-OFF, NYLON 0.50" TALL KEYSTONE, 8833 (SNAP ON)
PARTS LIST

7
DEMO MANUAL DC2958A
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.
SUNCON 63CE22BS
(2MHz)
SYNC SPREAD SPECTRUM PULSE SKIPPING BURST
FOR ASSEMBLY
VERSIONS
*
U1
LT8609AEDDM
DC2958A-B DC2958A-C
LT8609AEDDM-5
LT8609AEDDM-3.3
R4 1M
0 OHM 0 OHM
R5
187k
OPT OPT
C5
10pF OPT OPT
VOUT
5V 5V
3.3V
*
*
*
*
*
DC2958A-A
VCC
VCC
R2
18.2k
E6
EN/UV
L2 OPT
1 2
E5
SYNC
E9
GND
L1
2.2uH
XFL4020-222MEC
1 2
+
C1 22uF
12
R4
C6
47uF 10V 1210
E7
TR/SS
C11 1uF
50V 0805
C8
0.01uF
C4 0.1uF
C10 4.7uF 50V 1206
R3 49.9k
E8 PG
C7
1uF
R6 OPT
E3
VOUT
/ 3A
JP1
1 2 3 4 5 6 7 8
E4
GND
R1 1M
R5
C5
E1
VEMI
3V - 42V
C3 4.7uF 50V
1206
C13 0.1uF 50V
C2 4.7uF 50V 1206
FB1
MPZ2012S221AT000
1 2
U1
VIN
9
EN/UV
10
SYNC
5
VCC
3
TR/SS
7
RT
4
FB 6
PG 8
SW 2
BST 1
GND
11
C12 0.1uF 50V
C9 4.7uF 16V
0805
E2
GND
E10
VIN
3V - 42V
VOUT
SCHEMATIC DIAGRAM

8
DEMO MANUAL DC2958A
Rev. 0
 ANALOG DEVICES, INC. 2020
08/20
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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