Pin No.
Pin Name
I/O
Description
12
PGOOD
O
PGOOD is an open collector output used to indicate the status of
the converter output voltage. This pin is pulled low when the
converter output is not within 10% of the DACOUT reference
voltage. Exception to this behavivor is the 11111 VID pin com-
bination which disables the converter; in this case, PGOOD as-
serts a high level.
13
PHASE
O
Connect the PHASE pin to the upper MOSFET source. This pin
is used to monitor the voltage drop across the MOSFET for
over-current protection. This pin also provides the return path
for the upper gate drive.
14
UGATE
O
Connect UGATE to the upper MOSFET gate. This pin provides
the gate drive for the upper MOSFET.
15
BOOT
I
This pin provides bias voltage to the upper MOSFET driver. A
bootstrap circuit may be used to create a BOOT voltage suitable
to drive a standard N-Channel MOSFET.
16
PGND
P
This is the power ground connection. Tie the lower MOSFET
source to this pin.
17
LGATE
O
Connect LGATE to the lower MOSFET gate. This pin provides
the gate drive for the lower MOSFET.
18
VCC
P
Provide a 12V bias supply for the chip to this pin.
19
OVP
O
The OVP pin can be used to drive an external SCR in the event
of an overvoltage condition.
20
RT
I
This pin provides oscillator switching frequency adjustment. By
placing a resistor (R
T
) from this pin to GND, the nominal
200kHz switching frequency is increased.
5 10
R
(k )
T
Conversely, connecting a pull-up resistor (R
T
) from this pin to
VCC reduces the switching frequency.
4 10
R
(k )
T
F
S
200kHz +
6
(R
T
to GND)
F
S
200kHz +
7
(R
T
to 12V)
Absolute Maximum Ratings
Supply Voltage ......................................... +15V
Storage Temperature ............... 50 C to 125 C
Input Voltage ............... GND 0.3 to V
CC
+0.3V
Operating Temperature ............ 20 C to 75 C
Note: These are stress ratings only. Stresses exceeding the range specified under Absolute Maxi-
mumRatings maycausesubstantialdamagetothedevice.Functionaloperationofthisdevice
at other conditions beyond those listed in the specification is not implied and prolonged expo-
sure to extreme conditions may affect device reliability.
HT82P604B
3
March 23, 2000
Preliminary