User Manual

MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
20 ______________________________________________________________________________________
PIN
MAX1540 MAX1541
NAME FUNCTION
31 39 ON2
OUT2 Enable Input. Pull ON2 to GND to shut down controller 2 (OUT2). Connect to
V
CC
for normal operation. When discharge mode is enabled by OVP/UVP, the output
is discharged through a 10Ω resistor between OUT2 and GND, and DL2 is forced
high after V
OUT2
drops below 0.3V. When discharge mode is disabled by OVP/UVP,
OUT2 remains a high-impedance input and DL2 is forced low so LX2 also appears as
a high impedance. A rising edge on ON1 or ON2 clears the fault-protection latch.
32 40 ON1
OUT1 Enable Input. Pull ON1 to GND to shut down controller 1 (OUT1). Connect to
V
CC
for normal operation. When discharge mode is enabled by OVP/UVP, the output
is discharged through a 10Ω resistor between OUT1 and GND, and DL1 is forced
high after V
OUT1
drops below 0.3V. When discharge mode is disabled by OVP/UVP,
OUT1 remains a high-impedance input and DL1 is forced low so LX1 also appears as
high impedance. A rising edge on ON1 or ON2 clears the fault-protection latch.
Pin Description (continued)
Table 1. Component Selection for Standard Applications
MAX1540 MAX1541
COMPONENT
PWM1 PWM2 PWM1 PWM2
Input Voltage (V
IN
) 7V to 24V 7V to 24V 7V to 24V 7V to 24V
Output Voltage (V
OUT
_) 1.8V 2.5V 1.0V/1.5V 2.5V
Load Current (I
OUT
_) 4A 8A 4A 4A
S w i tchi ng Fr eq uency
( f
S W
_)
TON = REF (485kHz) TON = REF (355kHz) TON = REF (485kHz) TON = REF (355kHz)
Input Capacitor (C
IN
)
(2) 10µF, 25V
Taiyo Yuden TMK432BJ106KM
(2) 4.7µF, 25V
Taiyo Yuden TMK325BJ475KM
Output Capacitor
(C
OUT
_)
220µF, 6.3V, 12mΩ
Sanyo POSCAP
6TPD220M
330µF, 4V, 12mΩ
Sanyo POSCAP
4TPD330M
470µF, 4V, 10mΩ
Sanyo POSCAP
4TPD470M
220µF, 6.3V, 12mΩ
Sanyo POSCAP
6TPD220M
High-Side MOSFET
(N
H
_)
35mΩ, 30V
Fairchild 1/2 FDS6982S
20mΩ, 30V
Fairchild FDS6690
35mΩ, 30V
Fairchild 1/2 FDS6982S
35mΩ, 30V
Fairchild 1/2 FDS6982S
Low-Side MOSFET
(N
L
_)
22mΩ, 30V
Fairchild 1/2 FDS6982S
12.5mΩ, 30V
Fairchild FDS6670S
22mΩ, 30V
Fairchild 1/2 FDS6982S
22mΩ, 30V
Fairchild 1/2 FDS6982S
Low-Side Schottky
(D
L
_)
(if needed)
1A, 30V Schottky
Nihon EP10QS03L
1A, 30V Schottky
Nihon EP10QS03L
1A, 30V Schottky
Nihon EP10QS03L
1A, 30V Schottky
Nihon EP10QS03L
Inductor (L_)
2.5µH, 6.2A, 15mΩ
Sumida
CDEP105(H)-2R5
2.2µH, 10A, 4.4mΩ
Sumida
CDEP105(L)-2R2
1.8µH, 9.0A, 6.2mΩ
Sumida
CDEP105(S)-1R8
4.3µH, 6.8A, 8.7mΩ
Sumida
CDEP105(L)-4R3
R
SENSE_
15mΩ ±1%, 0.5W
IRC LR2010-01-R015F
or Dale WSL-2010-R015F
5mΩ ±1%, 0.5W
IRC LR2010-01-R005F
or Dale WSL-2010-R005F
15mΩ ±1%, 0.5W
IRC LR2010-01-R015F
or Dale WSL-2010-R015F
15mΩ ±1%, 0.5W
IRC LR2010-01-R015F
or Dale WSL-2010-R015F