Datasheet

LTC4362-1/LTC4362-2
6
436212fa
BLOCK DIAGRAM
Mobile devices like cell phones and MP3/MP4 players
have highly integrated subsystems fabricated from deep
submicron CMOS processes. The small form factor is
accompanied by low absolute maximum voltage ratings.
The sensitive electronics are susceptible to damage from
transient or DC overvoltage conditions from the power
supply.
Failures or faults in the power adaptor can cause an over-
voltage event. So can hot-plugging an AC adaptor into the
power input of the mobile device (see Application Note
88). Today’s mobile devices derive their power supply or
recharge their internal batteries from multiple alternative
inputs like AC wall adaptors, car battery adaptors and USB
ports. A user might unknowingly plug in the wrong adap-
tor, damaging the device with a high or even a negative
power supply voltage.
The LTC4362 protects low voltage electronics from these
overvoltage conditions by controlling an internal N-chan-
nel MOSFET confi gured as a pass transistor. At power-up
(V
IN
> 2.1V), a start-up delay cycle begins. Any overvolt-
age condition causes the delay cycle to continue until a
safe voltage is present. When the delay cycle completes,
an internal high-side switch driver slowly ramps up the
MOSFET gate, powering up the output at a controlled rate
and limiting the inrush current to the output capacitor.
CHARGE
PUMP
SENSE
RESISTOR
31mΩ
CONTROL
OVERCURRENT
COMPARATOR
OVERVOLTAGE
COMPARATOR
5µA
10µA
1.8M
200k
5.8V
5.8V
5.7V
+
–
GATE HIGH
COMPARATOR
GATE HIGH
THRESHOLD
+
–
+
–
500k
5.8V
OUT
GND
ON
PWRGD
GATEP
IN
SENSE
436212 BD
+
–
1V
+
–
47mV
OPERATION