AAT4621
PC Card Current Limit Interface
and Capacitor Charger
General Description
The AAT4621 SmartSwitch is a current limited P-
channel MOSFET power switch designed for high-
side load-switching applications in PC Card
GSM/GPRS/3G modem cards. Used in conjunc-
tion with a super capacitor, the AAT4621 will
ensure that the power ratings of the PCMCIA host
are not exceeded at any time. Featuring two inde-
pendent, programmable current limits and a power
loop, the AAT4621 can ensure that the super
capacitor can be charged without exceeding PCM-
CIA specifications. The current limit is set by two
external resistors allowing a ±10% current limit
accuracy over the normal operating temperature
range. The switch can be controlled from either of
the two enable inputs and in the off condition will
block currents in both directions. The AAT4621
also incorporates a System READY function which
can advise the system that the super capacitor is
fully charged and ready for use. Adjustable hys-
teresis is provided with the addition of an external
resistor. The quiescent supply current is typically a
low 40µA. In shutdown mode, the supply current
decreases to less than 1µA.
The AAT4621 is available in a thermally enhanced,
Pb-free, 12-pin TSOPJW or 14-pin TDFN33 pack-
age and is specified over the -40°C to 85°C tem-
perature range.
Features
•
•
SmartSwitch
™
•
•
•
•
•
•
•
•
•
V
IN
Range: 3.0V to 5.5V
Dual Independent Current Limits
— 75mA to 1200mA
— ±10% Current Accuracy
— 20°C Temperature Band
Reverse Current Blocking Protection
Power Loop
Low Quiescent Current
— 40µA Typical
— 1.0µA Max with Switch Off
65mΩ Typical R
DS(ON)
at 3V
Only 1.4V Needed for Enable Control Pin
System READY Output with Externally
Programmable Hysteresis
Under-Voltage Lockout
Temperature Range: -40 to 85°C
12-Pin TSOPJW Package or 14-Pin TDFN33
Package
Applications
•
•
•
•
•
Capacitor Charger
CF Card Port Power Protection
Express Card GSM/GPRS/3G Modems
PC Card GSM/GPRS Class 10/12 Modems
WiMAX Cards
Typical Application
Reverse
Blocking
100kΩ
OUT
Over-Temp
Protection
Under-
Voltage
Lockout
EN IL
EN
SUPERCAP
EN
OPERATION
EN IU
1.2V
Reference
Current
Limit
Control
ISETL
To Load
VCC
V
CC
Power
Loop
RDY
To μC
ISETU
GND
SuperCap
R
HYS
R
SETU
R
SETL
4621.2007.07.1.0
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ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
