MAX14653 Datasheet, PDF (8/11 Pages) Maxim Integrated Products – High-Current Overvoltage Protector with Adjustable OVLO

MAX14653/MAX14654/
MAX14655
Functional Diagram
High-Current Overvoltage Protector
with Adjustable OVLO
IN
IN
IN
OVLO
SEL
MAX14653
MAX14654
MAX14655
VBG
REFERENCE
TEMPERATURE
FAULTS
CHARGE
PUMP
LOGIC
CONTROL
GND
OUT
OUT
OUT
ACOK
Detailed Description
The MAX14653/MAX14654/MAX14655 overvoltage pro-
tection devices feature a low on-resistance (R_ON) internal
FET and protect low-voltage systems against voltage
faults up to +28V_DC. An internal clamp also protects
the devices from surges up to +80V. If the input voltage
exceeds the overvoltage threshold, the internal FET is
turned off to prevent damage to the protected compo-
nents. The 15ms debounce time built into the device
prevents false turn on of the internal FET during startup.
Device Operation
The devices contain timing logic that controls the turn-on
of the internal FET. The internal charge pump is enabled
when V_IN < V_{IN_OVLO} if internal trip thresholds are used
or when V_IN < V_{OVLO_TH} if external trip thresholds are
used. The charge-pump startup, which occurs after a
15ms debounce delay, turns the internal FET on (see the
Functional Diagram). After the debounce time, soft-start
limits the FET inrush current for 30ms (typ). At any time,
if V_IN rises above V_{OVLO_THRESH}, OUT is disconnected
from IN.
Internal Switch
The MAX14653/MAX14654/MAX14655 incorporate an
internal FET with a 38mΩ (typ) R_ON. The FET is internally
driven by a charge pump that generates a necessary gate
voltage above IN.
Overvoltage Lockout (OVLO)
The MAX14653 has a 15.5V (typ) overvoltage threshold
(OVLO). The MAX14654 and MAX14655 have 6.8V and
5.825V (typ) OVLO thresholds, respectively.
Thermal-Shutdown Protection
The MAX14653/MAX14654/MAX14655 feature thermal
shutdown circuitry. The internal FET turns off when the
junction temperature exceeds +130ºC (typ). The device
exits thermal shutdown after the junction temperature
cools by 20ºC (typ).
ACOK Output
An open-drain ACOK output gives the MAX14653/
MAX14654 /MAX14655 the ability to communicate a sta-
ble power source to the host system. ACOK is driven low
after input voltage is stable between minimum V_IN and
V_OVLO after debounce. Connect a pullup resistor from
ACOK to the logic I/O voltage of the host system. ACOK
is high impedance after thermal shutdown.
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