ZHCSJB5B September 2019 – December 2019 DRV8904-Q1 , DRV8906-Q1 , DRV8908-Q1 , DRV8910-Q1 , DRV8912-Q1
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
Active OLD can identify an open-load condition on the OUTX pins while driving a load. As shown in Figure 53, the DRV89xx identifies an open-load fault condition when the current through the MOSFET (IOUTX) is lower than the open-load current threshold (IOLD) for longer than the open-load deglitch time (tOLD). At that point the device takes the following actions.
Figure 53. 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,
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.
| 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 |
| 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 | ||
| 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 |