March 2017
DocID030364 Rev 1
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www.st.com
STEVAL-ISA200V1
High efficiency synchronous step-down regulator based on the
A6984
Data brief
Features
AECQ100 qualification
400 mA DC output current
4.5 V to 36 V operating input voltage
Synchronous rectification
Low consumption mode or low noise mode
100 µA IQ at light load (LCM VOUT = 3.3 V)
13 µA IQ-SHTDWN
Adjustable fSW (250 kHz - 600 kHz)
Output voltage adjustable from 0.9 V
No resistor divider required for 3.3 V VOUT
VBIAS maximizes efficiency at light load
350 mA valley current limit
Constant on-time control scheme
PGOOD open collector
Thermal shutdown
RoHS compliant
Description
The STEVAL-ISA200V1 product evaluation board
is based on the A6984 high-efficiency monolithic
synchronous step-down regulator, capable of
delivering up to 400 mA of DC current. The fixed
3.3 V output requires no external resistor divider.
The A6984 is especially suited for automotive
systems. The low consumption mode (LCM) is
designed for automotive applications that remain
active while the car is parked, maximizing
efficiency at light load with controlled output
voltage ripple. The low noise mode (LNM)
renders the switching frequency nearly constant
over the load current range, serving low noise
application specifications such as audio and
sensors. The PGOOD open collector output can
implement output voltage sequencing during the
power-up phase. The synchronous rectification,
designed for high efficiency at medium-heavy
load, and the high switching frequency capability
ensure a compact application size. Pulse-by-
pulse current sensing on the low-side power
element implements effective constant current
protection.
Schematic diagrams
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DocID030364 Rev 1
1 Schematic diagrams
Figure 1: STEVAL-ISA200V1 ciruit schematic
L1: LPS6225- 683MLC
C1: si ze 1210
C6, C7: si ze 1206
J4 passo 2. 54
J3
R4 1M
TP5
EN
J4 R8
0
L1 68uH
C9 NM
R6
100k
C2 100nF 50V
R2
NM
U1 A6984
PGOOD 1
EN
4
VIN
7
VCC 8
FB 2
GND
5
LX 6
TON
3VBIAS 9
LNM
10
EP
11
TP1 VBIAS
R5 NM
C7 NM
C1 10uF 50V
TP3
VIN
TP7
GND
R3 NM
R9 NM
R1 1Meg
TP6
GND
TP2 PGOOD
R7
NM
C4
470nF
C6 22uF
C3 NM
C5
NM
C10 NM
TP4 VOUT
C8
NM
J2
J1
STEVAL-ISA200V1
DocID030364 Rev 1
3/4
2 Revision history
Table 1: Document revision history
Date
Version
Changes
30-Mar-2017
1
Initial release.
STEVAL-ISA200V1
4/4
DocID030364 Rev 1
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