TC1303C-AO2EMF datasheet(18/36 Pages) MICROCHIP

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TC1303A/TC1303B/TC1303C/TC1304

DS21949B-page 18

3.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 3-1.

TABLE 3-1:

PIN FUNCTION TABLE

3.1

TC1303 LDO Shutdown Input Pin

(SHDN2)

SHDN2 is a logic-level input used to turn the LDO Reg-

ulator on and off. A logic-high (> 45% of VIN), will

enable the regulator output. A logic-low (< 15% of VIN)

will ensure that the output is turned off.

3.2

TC1304 Shutdown Input Pin

(SHDN)

SHDN is a logic-level input used to initiate the sequenc-

ing of the LDO output, then the buck regulator output.

A logic-high (> 45% of VIN), will enable the regulator

outputs. A logic-low (< 15% of VIN) will ensure that the

outputs are turned off.

3.3

LDO Input Voltage Pin (VIN2)

VIN2 is a LDO power input supply pin. Connect variable

input voltage source to VIN2. Connect VIN1 and VIN2

together with board traces as short as possible. VIN2

provides the input voltage for the LDO. An additional

capacitor can be added to lower the LDO regulator

input ripple voltage.

3.4

LDO Output Voltage Pin (VOUT2)

VOUT2 is a regulated LDO output voltage pin. Connect

a 1 µF or larger capacitor to VOUT2 and AGND for proper

operation.

3.5

Power-Good Output Pin (PG)

PG is an output level indicating that VOUT2 (LDO) is

within 94% of regulation. The PG output is configured

as a push-pull for the TC1303B and open-drain output

for the TC1303A, TC1303C and TC1304.

3.6

Analog Ground Pin (AGND)

AGND is the analog ground connection. Tie AGND to the

analog portion of the ground plane (AGND). See the

physical layout information in Section 5.0 “Application

Circuits/Issues” for grounding recommendations.

3.7

Buck Regulator Output Sense Pin

(VFB/VOUT1)

For VOUT1 adjustable-output voltage options, connect

the center of the output voltage divider to the VFB pin.

For fixed-output voltage options, connect the output of

the buck regulator to this pin (VOUT1).

3.8

Buck Regulator Shutdown Input

Pin (SHDN1)

SHDN1 is a logic-level input used to turn the buck

regulator on and off. A logic-high (> 45% of VIN), will

enable the regulator output. A logic-low (< 15% of VIN)

will ensure that the output is turned off.

Pin No.

TC1303

Name

TC1304

Name

Function

SHDN2

—

Active Low Shutdown Input for LDO Output Pin

—

SHDN

Active Low Shutdown Input both Buck Regulator Output and LDO Output.

Initiates sequencing up and down

2VIN2

VIN2

Analog Input Supply Voltage Pin

3VOUT2

VOUT2

LDO Output Voltage Pin

Power-Good Output Pin

5AGND

AGND

Analog Ground Pin

6VFB/VOUT1

VFB/VOUT1 Buck Feedback Voltage (Adjustable Version) / Buck Output Voltage

(Fixed Version) Pin

SHDN1

—

Active Low Shutdown Input for Buck Regulator Output Pin

7—

AGND

Analog Ground Pin

8VIN1

VIN1

Buck Regulator Input Voltage Pin

9LX

Buck Inductor Output Pin

PGND

Power Ground Pin

Exposed

Pad

Exposed

Pad

For the DFN package, the center exposed pad is a thermal path to remove

heat from the device. Electrically this pad is at ground potential and should

be connected to AGND

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