EN

LDO1

0

1

2

3

4

5

6

7

LDO2

Timing Code

Timing Code

START UP sequence

SHUT DOWN sequence

is in reverse order of START UP sequence

EN

LDO1

0

1

2

3

4

5

6

7

LDO2

LDO3

LDO3

LDO4

LDO4

LDO5

LDO5

BUCK

BUCK

STANDBY

START UP

SHUT DOWN

STANDBY

IDLE

Note 3

Note 3

Note 3

Note 3

Note 3

Note 4

Note 5

LP8720

www.ti.com

SNVS575B – JULY 2008 – REVISED MAY 2013

(1)

STARTUP and SHUTDOWN sequences are defined by registers. Sequences given here are valid if there the

registers are not rewritten via Serial Interface.

(2)

The timing showed here define time points when LDO’s and BUCK are enabled/disabled. Enabling /disabling process

duration depends on loading conditions. Buck startup duration is 140 µs for no load. LDO startup duration is no more

than 35 µs. For details please see LDO’s and BUCK Electrical Specifications.

(3)

LDO1, LDO2, LDO4, LDO5 and BUCK are disabled. If LDO1, LDO2, LDO4, LDO5 and/or BUCK are enabled via

Serial Interface and startup sequence is not changed via Serial interface, then LDO1, LDO2, LDO4, LDO5 and BUCK

are disabled with no delay from falling edge on EN-pin.

(4)

At this time point registers 0x09 and 0x0C are reset to POR default values.

(5)

At this time point registers 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07 and 0x08 are reset to POR default values.

Figure 3. Startup Sequence if DEFSEL=GND

DEFSEL

Startup Sequence

Shutdown Sequence

VBATT

LDO1, 2, 3, 4 enable same time.

In reverse order of startup sequence.

LDO5 and BUCK enable via Serial Interface.

GND

LDO3 enable.

In reverse order of startup sequence.

LDO1, 2, 4, 5 and BUCK enable via Serial Interface .

Hi-Z

LDO1, 2, 3, 4 enable same time.

In reverse order of startup sequence.

LDO5 and BUCK enable via Serial Interface.

(1)

When IDSEL= VBATT then slave address is 7h’7F.

When IDSEL= floating (Hi-Z) then slave address is 7h’7C.

When IDSEL= GND then slave address is 7h’7D.

Copyright © 2008–2013, Texas Instruments Incorporated

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