Datasheet
MAX8655
Highly Integrated, 25A, Wide-Input,
Internal MOSFET, Step-Down Regulator
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REFIN
The MAX8655 has a reference input (REFIN). When an
external reference up to 1.5V is connected to REFIN,
the feedback regulation voltage is equal to the voltage
applied to REFIN.
Connect REFIN to AVL to use the internal 0.7V reference.
Overvoltage Protection
The MAX8655 provides output overvoltage protection
(OVP). The OVP threshold is set independent of the
output regulation voltage with a resistor voltage-divider.
When the voltage at OVP exceeds the OVP threshold,
the regulator stops switching and latches on the low-
side power MOSFET. Cycle EN or the power applied to
AVL to clear the latch.
Power-Good Signal (POK)
POK is an open-drain output on the MAX8655 that mon-
itors the output voltage. When the output is above 92%
of its nominal regulation voltage, POK is high imped-
ance. When the output drops below 89% of its nominal
regulation voltage, POK is internally pulled low. POK is
also internally pulled low when the MAX8655 is shut
down or in a fault condition.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipa-
tion in the MAX8655. When the junction temperature
exceeds +160°C, an internal thermal sensor shuts
down the device, allowing the IC to cool. The thermal
sensor turns the IC on again after the junction tempera-
ture cools by 15°C, resulting in a pulsed output during
continuous thermal-overload conditions.
MAX8655
PVIN
PVIN
PVIN
PVIN
PVIN
LX
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
LX
LX
LX
LX
LX
OFF
ON
PVIN
C14
1µF
C8
0.47µF
C10
100pF
C12
470pF
C13
0.022µF
C15
0.22µF
C1–C3
3 x 10µF
CERAMIC
C16
0.22µF
R1
681Ω
R3
2.87kΩ
R12
80.6kΩ
R2
357Ω
R9
56.2kΩ
R7
40.2kΩ
L1
0.56µH
1.8mΩ
C18
2.2µF
R8
41.2kΩ
R13
100kΩ
R10
51.1kΩ
C9
0.47µF
C6–C20
4 x 100µF
CERAMIC
ENABLE
INPUT
INPUT
11.8V TO 13.2V
FOR INTERNAL
OSCILLATOR
OPERATION ONLY
POWER-OK OUTPUT
FSYNC INPUT
SYNC OUTPUT
OUTPUT 1.2V
UP TO 20A
AVL
D1
VL
AVL
LX
VLGND
GND
VL
IN
EN
AVL
GND
SCOMP
ILIM2
GND
REFIN
SS
COMP
FB
OVP
ILIM1
CS-
CS+
N.C.
N.C.
PVIN
PVIN
PVIN
PVIN
PVIN
PVIN
LXB
N.C.
GND
BST
SYNCO
MODE
FSYNC
POK
R5
4.02kΩ
Figure 3. Single-Phase, 600kHz Switching, 10.8V to 13.2V Input, and 1.2V/20A Output