AIC1880 Datasheet, PDF (6/11 Pages) Analog Intergrations Corporation – Low Noise, Step-Up PWM DC/DC Converter

BLOCK DIAGRAM
AIC1880
SHDN
COMP
FB
FREQ
SHUTDOWN _SHUTDOWN
CONTROL
ERROR
AMPLIFIER
1.24V
UNDER VOLTAGE
LOCK OUT
UVLO
SOFT-
START
ERROR
COMPARATOR
CONTROL
AND
1
N
DRIVER
CLOCK
LOGIC
OSCI-
LLATOR
SLOPE
COMPEN-
SATION
CURRENT
SENSE
RSENSE
VIN
SS
LX
GND
PIN DESCRIPTIONS
PIN 1: COMP - Compensation Pin for Error Am-
plifier.
PIN 2: FB
- Feedback Pin with a typical ref-
erence voltage of 1.24V.
PIN 3: SHDN
PIN 4:GND
PIN 5: LX
PIN 6: VIN
- Shutdown Control Pin. The De-
vice will turn off when SHDN is
Low.
- Ground.
- Switch Pin.
- Power Supply Pin.
PIN 7: FREQ
PIN 8: SS
- Frequency Select Pin. Oscillator
frequency is 640kHz when
FREQ connects to GND, and
1.2MHz when FREQ connects
to VIN.
- Soft-Start Control Pin. Connect a
soft-start capacitor to this pin. A
4µA constant current charges
the soft-start capacitor. Leave
open for no soft-start.
6