© 2002 Microchip Technology Inc.

DS21372B-page 3

TC125/TC126

2.0

PIN DESCRIPTIONS

Thedescriptionsof the pins arelistedinTable2-1.

TABLE 2-1:

PIN FUNCTION TABLE

TC125

Pin No.

(5-Pin SOT-23A)

TC126

Pin No.

(5-Pin SOT-23A)

Symbol

Description

1

—

SHDN

Shutdown input. A logic low on this input suspends device operation and

supply current is reduced to less than 0.5

µA. The device resumes normal

operation when SHDN is again brought high.

—

1

SENSE

Voltage sense input. This input provides feedback voltage sensing to the

internal error amplifier. It must be connected to the output voltage node,

preferably the single point in the system where tight voltage regulation is

most beneficial.

2

—

PS

Power and voltage sense input. This dual function input provides both

feedback voltage sensing and internal chip power. It should be connected

to the regulator output. (See Figure 3-1).

—2

Power supply voltage input.

3

3

NC

Not connected.

4

4

GND

Ground terminal.

5

5

LX

Inductor switch output. LX is the drain of an internal N-channel switching

transistor. This terminal drives the external inductor, which ultimately

provides current to the load.