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STEVAL-ISA152V1
3.3 V/3 A high efficiency step down DC-DC converter
(VIN= 4.5 to 60 V) based on the L7987
Data brief
Description
The STEVAL-ISA152V1 product evaluation board
is a step-down switching power supply based on
the L7987 regulator in an HTSSOP16 package.
The output voltage can be set starting from 0.8 V.
Low drop-out operation, with almost 100% duty
cycle, can be achieved.
The L7987 is a 61 V, 3 A step-down
asynchronous switching regulator with embedded
power MOSFET caable of delivering up to 3 A of
current, depending on the application conditions.
Features
•
•
•
•
•
•
•
•
•
•
3.3 V output voltage
3 A DC output current
4.5 V to 60 V input voltage
500 kHz switching frequency
3.5 ms programmed soft-start
VBIAS switch-over for improved efficiency at
light load
180° out of phase synchronization available
Open drain PGOOD available
Auto recovery overcurrent and thermal
protection
RoHS compliant
May 2014
The embedded switch-over feature on the VBIAS
pin and the light load management (pulse
skipping) are intended to maximize power
conversion efficiency across the entire load
range.
The soft-start, current limit threshold and the
switching frequency are adjustable for application
optimization.
The device includes an internal 250 kHz oscillator
that can be externally adjusted up to 1.5 MHz;
two L7987 regulators can be synchronized in a
180° out-of-phase configuration for reduced total
input RMS current.
DocID025489 Rev 1
For further information contact your local STMicroelectronics sales
office
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GND
EN
TP6
TP5
J1
R4
0
4.7uF 100V
C1
VIN
4.7uF 100V
C2
TP3
1uF 100V
C3
TP2
1uF 100V
C4
SYNCH
22nF
C10
R9
NM
R8
47k
11
10
6
5
4
2
3
7
U1
ILIM
FSW
SS
EN
VCC
VIN
VIN
SYNCH
GND
16
TP
17
L7987
NM
COMP
FB
LX
LX
BOOT
VBIAS
PGOOD
D1
100nF
C7
R3 0
STPS3L60
8
9
13
14
15
1
12
C11
power GND
R10
N.M.
1nF
620 C9
L1
signal GND
R6
J3
33nF
10uH
R2
R7
R11
2.2k
R5
J2
100k
68
6.8k
C8
10nF
47uF
2/4
C5
GSPG08112013DI1045
NM
TP7
TP4
TP1
GND
VOUT
PGOOD
1
C6
R1
Schematic diagram
STEVAL-ISA152V1
Schematic diagram
Figure 1: Schematic diagram
STEVAL-ISA152V1
2
Revision history
Revision history
Table 1: Document revision history
Date
Rev
09-May-2014
1
DocID025489 Rev 1
Changes
First release.
3/4
STEVAL-ISA152V1
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