APW6021
Functional Pin Description Cont.
DRIVE3 (Pin 18)
LGATE (Pin 25)
Connect this pin to the gate of an external MOSFET. Connect LGATE to the PWM converter’s lower
This pin provides the drive for the 1.5V regulator’s MOSFET gate. This pin provides the gate drive for
pass transistor.
the lower MOSFET.
VSEN3 (Pin 19)
PHASE (Pin 26)
Connect this pin to the output of the 1.5V linear Connect the PHASE pin to the PWM converter’s up-
regulator. This pin is monitored for under-voltage per MOSFET source. This pin represents the gate
events.
drive return current path and is used to monitor the
voltage drop across the upper MOSFET for over-cur-
rent protection.
COMP and FB (Pin 20, and 21)
COMP and FB are the available external pins of the UGATE (Pin 27)
PWM converter error amplifier. The FB pin is the in-
verting input of the error amplifier. Similarly, the COMP Connect UGATE pin to the PWM converter’s upper
pin is the error amplifier output. These pins are used MOSFET gate. This pin provides the gate drive for
to compensate the voltage-mode control feedback the upper MOSFET.
loop of the synchronous PWM converter.
VCC (Pin 28)
VSEN1 (Pin 22)
Provide a 12V bias supply for the IC to this pin. This
This pin is connected to the PWM converter’s output pin also provides the gate bias charge for all the
voltage. The PGOOD and OVP comparator circuits MOSFETs controlled by the IC. The voltage at this
use this signal to report output voltage status and for pin is monitored for Power-On Reset (POR) purposes.
over- voltage p ro te c tio n.
OCSET (Pin 23)
Connect a resistor from this pin to the drain of the
respective upper MOSFET. This resistor, an internal
200µA current source, and the upper MOSFET’s on-
resistance set the converter over-current trip point.
An over-current trip cycles the soft-start function.
The voltage at this pin is monitored for power-on re-
set (POR) purposes and pulling this pin low with an
open drain device will shutdown the IC.
PGND (Pin 24)
This is the power ground connection. Tie the syn-
chronous PWM converter’s lower MOSFET source
to this pin.
Copyright ANPEC Electronics Corp.
Rev. P.4 - Mar., 2001
7
www.anpec.com.tw
ANPEC [ ANPEC ELECTRONICS COROPRATION ]
