MAX15020 Datasheet, PDF (10/19 Pages) Maxim Integrated Products – 2A, 40V Step-Down DC-DC Converter with Dynamic Output-Voltage Programming

2A, 40V Step-Down DC-DC Converter with
Dynamic Output-Voltage Programming
VIN
7.5V TO 40V
C1
560µF
R1
97.5kΩ
R2
4.02kΩ
PWM
INPUT
R3
10kΩ
0Ω
C3
0.1µF
D2
IN
ON/OFF
DVREG
BST
LX
R5
C10
10Ω
1µF
REG
MAX15020
C2
1µF
FB
C9
0.1µF
REFIN
COMP
SS REFOUT SYNC GND FSEL PGND EP
C8
0.22µF
C5
0.1µF
C4
1µF _L1
22µH
D1
C13
330pF
R6
10kΩ
C11
0.027µF
C12
R9
0.1µF ^15.8kΩ
V_OUT
R7
10kΩ
C7
0.1µF
R8
340Ω
C6
560µF
Figure 2. Typical Application Circuit
Detailed Description
The MAX15020 voltage-mode step-down converter
contains an internal 0.2Ω power MOSFET switch. The
MAX15020 input voltage range is 7.5V to 40V. The
internal low R_DS(ON) switch allows for up to 2A of out-
put current. The external compensation, voltage feed-
forward, and automatically adjustable maximum ramp
amplitude simplify the loop compensation design allow-
ing for a variety of L and C filter components. In shut-
down, the supply current is typically 6µA. The output
voltage is dynamically adjustable from 0.5V to 36V.
Additional features include an externally programmable
UVLO through the ON/OFF pin, a programmable soft-
start, cycle-by-cycle current limit, hiccup-mode output
short-circuit protection, and thermal shutdown.
Internal Linear Regulator (REG)
REG is the output terminal of the 8V LDO powered from
IN and provides power to the IC. Connect REG exter-
nally to DVREG to provide power for the internal digital
circuitry. Place a 1µF ceramic bypass capacitor, C2,
next to the IC from REG to GND. During normal opera-
tion, REG is intended for powering up only the internal
circuitry and should not be used to supply power to the
external loads.
UVLO/ON/OFF Threshold
The MAX15020 provides a fixed 7V UVLO function
which monitors the input voltage (V_IN). The device is
held off until V_IN rises above the UVLO threshold.
ON/OFF provides additional turn-on/turn-off control.
Program the ON/OFF threshold by connecting a resis-
tive divider from IN to ON/OFF to GND. The device
turns on when V_ON/OFF rises above the ON/OFF thresh-
old (1.225V), given that V_IN has risen above the UVLO
threshold.
Driving ON/OFF to ground places the IC in shutdown.
When in shutdown the internal power MOSFET turns
off, all internal circuitry shuts down, and the quiescent
supply current reduces to 6µA (typ.). Connect an RC
network from ON/OFF to GND to set a turn-on delay
that can be used to sequence the output voltages of
multiple devices.
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