rt9205 Richtek Technology Corporation, rt9205 Datasheet - Page 5

• Manufacturer Part Number: rt9205
• Description: Dual Regulators - Synchronous Buck Pwm Dc-dc And Linear Controller
• Manufacturer: Richtek Technology Corporation

Functional Pin Description
LGATE (Pin 1)
Connect the LGATE pin to the gate of lower MOSFET.
This pin provides the gate drive for the lower MOSFET.
PGND/GND (Pin 2, 3)
Signal and power ground for the IC. All voltage levels are
measured with respect to this pin.
VCC (Pin 4)
This is the main bias supply for the RT9205/A. This pin
also provides the gate bias charge for the gate of lower
MOSFET. The voltage at this pin is monitored for ensuring
a proper power-on reset (POR). This pin is also the out
of an internal 6.0V regulator that powered from the BOOT
pin when the BOOT pin is directly powered from ATX
12V.
DRV (Pin 5)
This pin is the output of a linear controller. It should be
connected to the base of an external bypass NPN
transistor or the gate of a N-MOSFET to form a linear low
dropout regulator.
FBL (Pin 6)
This pin is connected to the output resistor-divider of an
external power transistor or a N-MOSFET based low
dropout regulator for regulating and monitoring the output
voltage. This pin is also connected to the protection
monitor and the invertering input of error amplifier of
internal linear regulator inside the IC.
FB (Pin 9)
This pin is connected to the PWM converter's output-divider
for regulating and monitoring the output voltage of buck
converter. This pin also connects to the protection monitor
and the inverting input of internal PWM error amplifier inside
the IC.
DS9205/A-09 October 2008
BOOT (Pin 13)
This pin provides ground referenced bias voltage to the
upper MOSFET driver. A bootstrap circuit is used to create
a voltage that is suitable for driving a logic-level N-MOSFET
when operating at a single 5V power supply. This pin also
could be powered from ATX 12V, in this situation, an internal
6.0V regulator will supply to VCC pin for generating bias
required inside the IC.
UGATE (Pin 14)
Connect the UGATE pin to the gate of upper MOSFET.
This pin provides the gate drive for the upper MOSFET.
NC (Pin 7,8,10,11,12)
No Connection.
RT9205/A
www.richtek.com
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