XRP7708 Datasheet, PDF (6/27 Pages) Exar Corporation – Quad Channel Digital PWM Step Down Controller

PIN ASSIGNMENT
XRP7708
Quad Channel Digital PWM Step Down Controller
Fig. 3: XRP7708 Pin Assignment
PIN DESCRIPTION
Name
VIN1
VIN2
VCCA
VCCD
PGND1- PGND4
AVDD
Pin Number
39
38
37
26
36,31,16,21
1
Description
Power source for the internal linear regulators to generate VCCA, VDD and the Standby
LDO (LDOOUT). Place a decoupling capacitor close to the controller IC. Also used in
UVLO1 fault generation – if VIN1 falls below the user programmed limit, all channels
are shut down. The VIN1 pin needs to be tied to VIN2 on the board with a short trace.
If the Vin2 pin voltage falls below the user programmed UVLO VIN2 level all channels
are shut down. The VIN2 pin needs to be tied to VIN1 on the board with a short trace.
Output of the internal 5V LDO. This voltage is internally used to power analog blocks.
Note that a compensation capacitor should be used on this pin (see application note).
Gate Drive input voltage. This is not an output voltage. This pin can be connected to
VCCA to provide power for the Gate Drive. VCCD should be connected to VCCA with the
shortest possible trace and decouple with a minimum 1µF capacitor. Alternatively,
VCCD could be connected to an external supply (not greater than 5V).
Power Ground. Ground connection for the low side gate driver.
Output of the internal 1.8V LDO. A decoupling capacitor should be placed between
AVDD and AGND close to the chip (with short traces).
© 2010 Exar Corporation
6/27
Rev. 1.0.3