TC1303A-AO2EMFTR datasheet(22/36 Pages) MICROCHIP

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TC1303A/TC1303B/TC1303C/TC1304

DS21949B-page 22

4.6

TC1304 Sequencing

The TC1304 device features an integrated sequencing

option. A sequencing circuit using only the SHDN input,

(Pin1), will turn on the LDO output (VOUT2) and delay

the turn on of the Buck Regulator output (VOUT1) until

the LDO output is in regulation. During power-down,

the sequencing circuit will turn off the Buck Regulator

output prior to turning off LDO output.

FIGURE 4-2:

TC1304 Sequencing Circuit.

FIGURE 4-3:

TC1304 Power-up Timing

from SHDN.

4.7

Soft Start

Both outputs of the TC1303/TC1304 are controlled

during start-up. Less than 1% of VOUT1 or VOUT2 over-

shoot is observed during start-up from VIN rising above

the UVLO voltage or either SHDN1 or SHDN2 being

enabled.

4.8

Overtemperature Protection

The TC1303/TC1304 has an integrated overtempera-

ture protection circuit that monitors the device junction

temperature and shuts the device off if the junction tem-

perature exceeds the typical 165°C threshold. If the

overtemperature threshold is reached, the soft start is

reset so that, once the junction temperature cools to

approximately 155°C, the device will automatically

restart.

Enable

VOUT2

VOUT1

–

160 µs Delay*

92% of VOUT2

92% of VOUT1

To PG

Delay CKT.

SHDN

* 160 µs delay on trailing edge

VIN1/VIN2

VOUT1

VOUT2

Power Good

Power Up Timing From SHDN

300ms

tWK + tS

500 µs

TC1304

SHDN

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