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L5953

Figure 3. Output Timing

Figure 4. Serial Input Timing

FUNCTIONAL DESCRIPTION

REG1 Stand-by Regulator (Figure 5)

The stand-by regulator output voltage can be 5V or 3.3V. It is externally selectable by means of the ADJ pin:

- leaving the ADJ pin open, the output voltage is 5V;

- connecting the ADJ pin to the Vstby pin the output voltage becomes 3.3V.

This regulator is supplied by STCAP pin and provide the reset information.

It has a current protection which limits the maximum allowable output current.

Reset (Figure 6)

The RES pin is an open collector that is activated (that is forced to zero) when the stand-by regulator is not in

regulation (including thermal shutdown and faults). The indication that REG1 is in regulation is delayed by a time

C

Q

AI01070B

S

MSB OUT

MSB-1 OUT

LSB OUT

D

ADDR.LSB IN

tSHQZ

tCH

tCL

tQLQH

(CPOL=0, CPHA=0)

tQHQL

tCLQX

tQVCL

C

D

AI01071

S

MSB IN

Q

tDVCH

HIGH IMPEDANCE

LSB IN

tSLCH

tCHDX

tDLDH

tDHDL

tCHCL

tCLCH

tCLSH

tSHSL

(CPOL=0, CPHA=0)