SLVSEC9C Data sheet

SLVSEC9C September 2019 – February 2020 DRV8904-Q1 , DRV8906-Q1 , DRV8908-Q1 , DRV8910-Q1 , DRV8912-Q1

PRODUCTION DATA.

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Mechanical Data (Package|Pins)

PWP|24
- MPDS372A

Thermal pad, mechanical data (Package|Pins)

Orderable Information

8.3.3.5.1 Active OLD

Active OLD can identify an open-load condition on the OUTX pins while driving a load. As shown in Figure 59, the DRV89xx identifies an open-load fault condition when the current through the MOSFET (I_OUTX) is lower than the open-load current threshold (I_OLD) for longer than the open-load deglitch time (t_OLD). At that point the device takes the following actions.

OLD bit in the IC status (IC_STAT) register sets to 1
HBX_HS_OLD or HBX_LS_OLD bit in the open-load status register (OLD_STAT_X) sets to 1 (depending if the fault is on the high-side MOSFET or low-side MOSFET, respectively).
nFAULT pin is drives low to indicate a fault to the controller.

DRV8904-Q1 DRV8906-Q1 DRV8908-Q1 DRV8910-Q1 DRV8912-Q1 drv89xx-OLDA.gif

Figure 59. Active open-load detection

Normal operation resumes (driver operation resumes, the nFAULT pin goes high, OLD bit is reset to 0) when the open-load condition is removed (the user reconnects the load to the OUTX connection) and the controller writes the CLR_FLT bit to 1.

NOTE

After the open-load fault condition is removed, the nFAULT pin will be driven high and the fault status are removed when,

CLR_FLT command is issued after deglitch time (t_OLD) while OUTX is set high.
CLR_FLT command is issued after OUTX is set to Hi-Z.
CLR_FLT command is issued after HBX_OLD_DIS bit is set.

By default, OLD on the DRV89xx-Q1 devices is enabled. The OLD control registers (OLD_CTRL_1 and OLD_CTRL_2) allow the user to disable OLD on the OUTX pins with the HBX_OLD_DIS bits. The OLD_OP bit in the OLD_CTRL_2 register determines the response of the device to an active OLD fault. If OLD_OP = 0, the OUTX pins go to the Hi-Z state to stop driving the outputs. If OLD_OP = 1, the OUTX pins stay in their previous state and do not react to the OLD fault unless the user takes action. Similarly, the OLD_REP bit determines if the OLD fault will report on the nFAULT pin or only in the IC_STAT register. Table 8 summarizes the open-load detection feature and conditions.

NOTE

By default the OLD feature is enabled, the outputs disable (go Hi-Z) when the OLD flags, and the nFAULT pin will report the OLD.

Table 8. OLD Configuration

LOAD / OPEN	REGISTER SETTINGS	OLD_OP	OLD_REP	OUT1	OUT2	nFAULT	BITS EFFECTED	RECOVERY
Half-Bridge Load Connected	HB1_HS_EN = 1	X	X	H	X	HIGH	N/A	N/A
Half-Bridge Load Connected	HB1_LS_EN = 1	X	X	L	X	HIGH
Full-Bridge Load Connected	HB1_HS_EN = 1 HB2_LS_EN = 1	X	X	H	L	HIGH
Full-Bridge Load Connected	HB1_LS_EN = 1 HB2_HS_EN = 1	X	X	L	H	HIGH
Half-Bridge Open	HB1_HS_EN = 1	0	0	Hi-Z	X	LOW	OLD = 1 (IC_STAT) HB1_HS_OLD = 1	OLD Condition Removed CLR_FLT = 1
		0	1	Hi-Z	X	HIGH
		1	0	H	X	LOW
		1	1	H	X	HIGH
	HB1_LS_EN = 1	0	0	Hi-Z	X	LOW	OLD = 1 (IC_STAT) HB1_LS_OLD = 1
		0	1	Hi-Z	X	HIGH
		1	0	L	X	LOW
		1	1	L	X	HIGH
Full-Bridge Open	HB1_HS_EN = 1 HB2_LS_EN = 1	0	0	Hi-Z	Hi-Z	LOW	OLD = 1 (IC_STAT) HB1_HS_OLD = 1 or HB2_LS_OLD = 1 ⁽¹⁾
		0	1	Hi-Z	Hi-Z	HIGH
		1	0	H	L	LOW
		1	1	H	L	HIGH
	HB1_LS_EN = 1 HB2_HS_EN = 1	0	0	Hi-Z	Hi-Z	LOW	OLD = 1 (IC_STAT) HB1_LS_OLD = 1 or HB2_HS_OLD = 1 ⁽²⁾
		0	1	Hi-Z	Hi-Z	HIGH
		1	0	L	H	LOW
		1	1	L	H	HIGH

(1) Either of the HB1_HS_OLD or HB2_LS_OLD will set depending upon which half-bridge OLD triggers first.

(2) Either of the HB1_LS_OLD or HB2_HS_OLD will set depending upon which half-bridge OLD triggers first.