Datasheet

MAX5976A/MAX5976B
2.7V to 18V, 7A, Hot-Swap Solution
8
Power-Good Delay
The devices feature an open-drain, power-good output
that asserts after 16ms (typ), indicating that OUT has
reached (0.9 x V
IN
) voltage.
REG
The devices include a linear regulator that outputs
2.6V at REG. REG provides power to the internal circuit
blocks of the ICs and must not be loaded externally. REG
requires a 1FF capacitor to ground for proper operation.
Fault Status Output (FAULT)
FAULT is an open-drain output that pulls low when a cur-
rent limit or an overtemperature fault shutdown occurs.
FAULT remains low until the next startup cycle. FAULT is
capable of sinking up to 5mA when asserted.
Thermal Protection
The devices enter a thermal shutdown mode in the event
of overheating caused by excessive power dissipation
or high ambient temperature. When the junction tem-
perature exceeds T
J
= +150NC (typ), the internal thermal
protection circuitry turns off the internal power MOSFET.
The devices recover from thermal shutdown mode once
the junction temperature drops by 20NC (typ).
Applications Information
Setting the Undervoltage Threshold
The devices feature an independent ON/OFF control
(ON1) for the internal MOSFET. The devices operate
with a 2.7V to 18V input voltage range and has a default
2.5V (typ) undervoltage lockout threshold. The internal
MOSFET remains off as long as V
IN
< 2.5V and/or V
ON1
< V
ON1_TH
. The undervoltage lockout threshold is pro-
grammable using a resistive divider between ON1 and
GND (Figure 1). When V
IN
is greater than 2.7V and V
ON1
exceeds the 1.21V (typ) threshold, the gate of the inter-
nal MOSFET enhances to 5V, with respect to V
IN
and the
devices' internal switch goes into normal operation. Use
the following equation to calculate the resistors values for
the desired undervoltage threshold:
IN
ON1_TH
V
R1 - 1 R2
V
 
= ×
 
 
 
where V
IN
is the desired turn-on voltage for the output
and V
ON1
is 1.21V. R1 and R2 create a resistive divider
from V
IN
to ON1. During normal operating conditions,
V
ON1
must remain above its 1.21V (typ) threshold. If
V
ON1
falls 100mV (V
ON1_HYS
) below the threshold, the
internal MOSFET turns off, disconnecting the load from
the input.
Setting the Current Limit
An external resistor from CB to ground sets the current
limit for the devices. Use the following formula to set the
current limit:
LIMIT CB
0.175A
I (A) R ( )
1000
 
= × Ω
 
Ω
 
Package Information
For the latest package outline information and land patterns,
go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package
drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
Chip Information
PROCESS: BiCMOS
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
16 TQFN-EP T1655+3
21-0140 90-0073