TS3405 Datasheet, PDF (2/10 Pages) Taiwan Semiconductor Company, Ltd – Single Synchronous Buck PWM Controller

Pin Descriptions
No.
Pin.
1
Boot
2
Ugate
3
Gnd
4
Lgate
5
Vcc
6
FB
7
COMP
8
Phase
Block Diagram
Descriptions
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-lever N-channel
MOSFET. It can take 20V as the maximum voltage. It can be powered by a DC power
supply or powered by a boost strap circuit.
This pin provides the PWM controlled gate driver for the upper MOSFET. It is also
monitored by the adaptive shoot-through protection circuitry to determine when the
upper MOSFET can be turned on. The sourcing Rds(on) is 15Ω and the sink Rds(on) is
7Ω. Ugate can handle high voltage up to maximum 20V.
This pin represents the signal and power ground for the IC. Tie this pin to the ground
island/plane through the lowest impedance connection available.
This pin provides the PWM controlled gate drive for the lower MOSFET. This pin is also
monitored by the adaptive shoot-through protection circuitry to determine when the
lower MOSFET can be turned on.
This pin provides the bias supply for the TS3405, as well as the lower MOSFET’s gate.
Connect a well-decoupled 5V supply to this pin.
This pin is the inverting input of the internal error amplifier. Use this pin in combination
with the COMP Pin to compensate the voltage-control feedback loop of the converter.
During soft start and all the time during normal converter operation, this pin represents
the output of the error amplifier. Use this pin in combination with the FB pin to
compensate the voltage control feedback loop of the converter. Pulling COMP to a level
below 0.3V enables soft start process. The whole soft start process takes about 5mS.
This pin is used to monitor the voltage drop across the lower MOSFET for over current
protection. The OCP threshold is –30mV. If Phases is less thean –300mV, the upper
MOSFET cannot be turned-on in the next cycle.
TS3405
2-10
2003/12 rev. A