TC120_13 Datasheet, PDF (4/16 Pages) Microchip Technology – PWM/PFM Step-Down Combination Regulator/Controller

TC120
2.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1: PIN FUNCTION TABLE
Pin No.
(8-Pin SOP)
1
2
3
4
5
6
7
8
Symbol
Description
V_IN
EXTW
CPC
SHDN/SS
SENSE
GND
EXT
Lx
Unregulated supply input.
Extended external switching transistor drive output. This output follows the timing on the EXT
output with an additional 100nsec blanking time on both the leading and trailing edges. That is,
this output transitions from high-to-low 100 nsec prior to the same transition on EXT; and
transitions low-to-high 100nsec after the same transition on EXT; resulting in a longer external
switch ON time. (See Section 3.9 External Switching Transistor Selection).
Charge pump capacitor input. An inverting charge pump is formed by attaching a capacitor and
diode to this input. (See Section 3.5 Improving High Load Efficiency In Regulator Operating
Mode).
Shutdown and soft-start control input. A soft start capacitor of 100pF (min) must be connected to
this input. The soft start capacitor is charged by an internal A current source that gently ramps
the TC120 into service. Shutdown control is best implemented with an external open collector (or
open drain) switch. The TC120 enters shutdown when this input is low. During shutdown, the
regulator is disabled, and supply current is reduced to less than 2.5A. Normal operation is
restored when this input is open-circuited, and allowed to float high. (See Section 3.6 Low Power
Shutdown Mode/Soft Start Input).
Voltage sense input. This input must be connected to the output voltage node at the physical
location that requires the tightest voltage regulation.
Ground terminal.
External switching transistor drive output. This output connects directly to the gate of an external
P-channel MOSFET for applications requiring output currents greater than 600mA. The timing of
this output exactly matches that of the gate drive for the internal P-channel transistor. This output
can drive a maximum capacitance of 1000pF. (See Section 3.9 External Switching Transistor
Selection).
Inductor terminal. This pin is connected to the drain of the internal P-channel switching transistor.
If the TC120 is operated as a regulator (i.e., using the internal switch); the inductor must be
connected between this pin and the SENSE pin.
DS21365C-page 4
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