rt9202 ETC-unknow, rt9202 Datasheet - Page 6

• Manufacturer Part Number: rt9202
• Description: Single Synchronous Buck Dc-dc Controller
• Manufacturer: ETC-unknow

RT9202
Functional Pin Description
BOOT (Pin 1)
This pin provides ground referenced bias voltage to the
upper MOSFET driver. A bootstrap circuit is used to
create a voltage suitable to drive a logic-level N-
channel MOSFET when operating at a single 5V power
supply. This pin also could be powered from ATX 12V,
in this situation, a internal 6.0V regulator will supply to
VCC pin for internal voltage bias.
UGATE (Pin 2)
Connect UGATE pin to the PWM converter’s upper
MOSFET gate. This pin provides the gate drive for the
upper MOSFET.
GND (Pin 3)
Signal and power ground for the IC. All voltage levels
are measured with respect to this pin.
LGATE (Pin 4)
Connect LGATE to the PWM converter’s lower
MOSFET gate. This pin provides the gate drive for the
lower MOSFET.
VCC (Pin 5)
This is the main bias supply for the RT9202. This pin
also provides the gate bias charge for the lower
MOSFETs gate. The voltage at this pin monitored for
power-on reset (POR) purpose. This pin is also the
internal 6.0V regulator output powered from BOOT pin
when BOOT pin is directly powered from ATX 12V.
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6
Protection
FB Over-Voltage Trip
FB Under-Voltage Trip
OCSET Current Source
Soft-Start Interval
Parameter
I
Symbol
OCSET
FB Rising
FB Falling
V
OCSET
Test Conditions
= 4.5V
FB (Pin 6)
This pin is connected to the PWM converter’s output
divider. This pin also connects to internal PWM error
amplifier inverting input and protection monitor.
OCSET (Pin 7)
Connect a resistor from this pin to the drain of the
respective upper MOSFET. This resistor, an internal
40µA current source, and the upper MOSFET 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 reset
(POR) purpose and pulling this pin low with an open
drain device will shut down the IC.
PHASE (Pin 8)
This pin is used to monitor the voltage drop across the
upper MOSFET for over-current protection.
I
PEAK
=
I
OCSET
R
DS
×
Min
1.0
35
(
R
--
ON
1
OCSET
)
DS9202-02 August 2002
Typ
1.1
0.5
40
2
Max
0.6
45
--
4
Units
mS
µA
V
V