RT8802A
Functional Pin Description
VTT/EN (Pin 1)
The pin is defined as the chip enable, and the VTT is
applied for internal VID pull high power and power sequence
monitoring.
DVD (Pin 12)
VR_Ready (Pin 2)
Power good open-drain output.
FBRTN (Pin 3)
Feedback return pin. VID DAC and error amplifier reference
for remote sensing of the output voltage.
FB (Pin 4)
Inverting input pin of the internal error amplifier.
COMP (Pin 5)
Output pin of the error amplifier and input pin of the PWM
comparator.
SS (Pin 6)
Connect this SS pin to GND with a capacitor to set the
soft-start time interval.
QRSEL (Pin 7)
Quick response mode select pin. When QRSEL = GND
and quick response is triggered during heavy load to light
load transient, 2 channels will turn on simultaneously to
prevent V
OUT
undershoot. When QRSEL = NC and quick
response is triggered, all channels will turn on
simultaneously to prevent V
OUT
undershoot.
VR_FAN (Pin 8)
The pin is defined to signal VR thermal information for
external VR thermal dissipation scheme triggering.
VR_HOT (Pin 9)
The pin is defined to signal VR thermal information for
external VR thermal dissipation scheme triggering.
TSEN (Pin 10)
Temperature detect pin for VR_HOT and VR_FAN.
OFS (Pin 14)
The pin is defined for load line offset setting.
ADJ (Pin 15)
Current sense output for active droop adjusting. Connect
a resistor from this pin to GND to set the load droop.
TCOC (Pin 16)
Input pin for setting thermally compensated over current
trigger point. Voltage on the pin is compared with V
ADJ
. If
V
ADJ
> V
TCOC
then OCP is triggered.
IMAX (Pin 17)
The pin is defined to set threshold of over current.
ISN1 (Pin 18)
Current sense negative input pin for channel 1 current
sensing.
ISN24 (Pin 19)
Current sense negative input pins for channel 2 and
channel 4 current sensing.
ISN35 (Pin 20)
Current sense negative input pins for channel 3 and
channel 5 current sensing.
Programmable power UVLO detection input. Trip threshold
is 1V at V
DVD
rising.
RT (Pin 13)
The pin is defined to set internal switching operation
frequency. Connect this pin to GND with a resistor R
RT
to
set the frequency F
SW
.
F
SW
=
4.463 e
9
R
RT
+
3500
IOUT (Pin 11)
Output current indication pin. The current through IOUT
pin is proportional to the total output current.
All brandname or trademark belong to their owner respectively
DS8802A-04 August 2007
www.richtek.com
3
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
