L99LD21 datasheet(34/73 Pages) STMICROELECTRONICS

34 / 73 page

SPI functional description

L99LD21

34/73

DS11130 Rev 5

CR#2: Control Register 2

Address:

0x02h

Type:

R/W

UNLOCK

[0]: bits GOSTBY, EN and BST_DIS cannot be set to 1

[1]: bits GOSTBY, EN and BST_DIS can be set to 1 with the next SPI

frame

If UNLOCK = 1, then it is always automatically reset with the next valid

SPI frame

Parity bit

ODD parity bit check

Table 14. CR#1: Control Register 1 (continued)

Bit

Default

Name

Description

9876

543210

IL1_PEAK

IL2_PEAK

VLED_TOFF1

VLED_TOFF2

Table 15. CR#2: Control Register 2

Bit

Default

Name

Description

23÷18

Set by OTP

(see Table 29)

IL1_PEAK

Inductor Peak Current selection bits for Buck1

17÷12

100000

IL2_PEAK

Inductor Peak Current selection bits for Buck2

11÷8

Set by OTP

(see Table 30)

VLED_TOFF1

Constant VLEDxTOFF Selection bits for Buck1:

0000: 10 V*µs;

1111: 72 V*µs; see Table 18

7÷4

1111

VLED_TOFF2

Constant VLEDxTOFF Selection bits for Buck2:

0000: 10 V*µs;

1111: 72 V*µs; see Table 18

GOSTBY

Standby Mode Bit:

0: Device waked up

1: Standby (if EN = 0)

GOSTBY can be set to 1 only if UNLOCK = 1; in other words, trying to

set this bit to 1 when UNLOCK = 0 will have no effects and it will

maintain its previous value.

GOSTBY can be reset to 0 also when UNLOCK = 0.

To set Standby mode it is necessary to send two consecutive SPI

frames, as follows:

1st SPI write operation to set UNLOCK bit to 1 (CR#1, bit1)

2nd SPI write operation to set GOSTBY bit to 1 and EN bit to 0

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