SLUSF28 Data sheet

SLUSF28 November 2023 TPS546A24S

PRODUCTION DATA

Package Options

Mechanical Data (Package|Pins)

RVF|40
- MPQF268C

Thermal pad, mechanical data (Package|Pins)

RVF|40
- QFND333E

Orderable Information

6.6.53 (65h) TOFF_FALL

CMD Address	65h
Write Transaction:	Write Word
Read Transaction:	Read Word
Format:	SLINEAR11 per CAPABILITY
Phased:	No
NVM Back-up:	EEPROM
Updates:	On-the-fly

The TOFF_FALL command sets the time, in milliseconds, from the end of the turnoff delay time until the voltage is commanded to zero. Note that this command can only be used with a device whose output can sink enough current to cause the output voltage to decrease at a controlled rate. This effectively sets the slew rate of the reference DAC during the soft-off period. Note that the fall time is equal to TOFF_FALL regardless of the value of the target output voltage or VOUT_SCALE_LOOP for the purposes of slew rate selection based on the target output voltage.

Due to hardware limitations in the resolution of the reference DAC slew-rate control, longer TOFF_FALL times with higher (21h) VOUT_COMMAND voltages can result in some quantization error in the programmed TOFF_FALL times with several TOFF_FALL times producing the same VOUT slope and TOFF_FALL time even with different TOFF_FALL settings, or different TOFF_FALL times for the same TOFF_FALL setting and different (21h) VOUT_COMMAND voltages.

Figure 6-59 (65h) TOFF_FALL Register Map

15	14	13	12	11	10	9	8
RW	RW	RW	RW	RW	RW	RW	RW
TOFFF_EXP					TOFFF_MAN

7	6	5	4	3	2	1	0
RW	RW	RW	RW	RW	RW	RW	RW
TOFFF_MAN

LEGEND: R/W = Read/Write; R = Read only

Table 6-70 Register Field Descriptions

Bit	Field	Access	Reset	Description
15:11	TOFFF_ EXP	RW	11110b	Linear format two’s complement exponent. Exponent = -2, LSB = 0.25 ms
10:0	TOFFF_ MAN	RW	NVM	Linear format two’s complement mantissa

Attempts to write (65h) TOFF_FALL beyond the supported range will be considered invalid/unsupported data and cause the TPS546A24S to respond by flagging the appropriate status bits and notifying the host according to the PMBus 1.3.1 Part II specification section 10.9.3. (65h) TOFF_FALL supports values from 0.5 ms to 31.75 ms in 0.25-ms steps. Values less than 0.5 ms will be implemented as 0.5 ms.