ZHCSJB5B September 2019 – December 2019 DRV8904-Q1 , DRV8906-Q1 , DRV8908-Q1 , DRV8910-Q1 , DRV8912-Q1
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
The DRV89XX-Q1 devices implement multiple open-load detection schemes to allow the controller to determine if a load is connected to the OUTX terminals. The OLD schemes available in DRV89XX-Q1 are listed below. Table 7 summarizes the use-cases for each OLD scheme.
PASSIVE OLD | ACTIVE OLD | LOW-CURRENT
ACTIVE OLD |
NEGATIVE-CURRENT
ACTIVE OLD |
|
---|---|---|---|---|
Part numbers | DRV8908/06/04-Q1 | DRV8912/10/08/06/04-Q1 | ||
When is it used | Detects open-load condition prior to enabling the outputs | Detects the open-load condition while driving a load | Detects the open-load condition while driving a load with small operating current | Detects the open-load condition during current re-circulation (on high-side or low-side) when synchronous rectification is enabled for both half-bridge and full-bridge configurations |
State of OUTx for valid OLD | Hi-Z (outputs disabled) | H/L | L | H/L |
OLD Trigger Condition | VOLx_HS(+) > VOLx_HS or
VOLx_LS(-) < VOLx_LS |
IOUTX < IOLD | IOUTX < IOLD_LOW | IOUTX > IOLD_NEG |
Tradeoffs | Passive OLD sequence is not enabled if any other fault other than OCP/OLD is present. | A false flag can occur during current re-circulation if synchronous rectification is ON. Enabling Negative-current OLD will solve this. A false flag can also occur if the operating current for the load is small (below IOLD threshold). See Low-current OLD for solution. | Only applicable for the current flowing in the low-side FETs. The IOCP for the low-side FET is also reduced by 11 times. The RDS(ON) of the low-side FET will increase by 11 times, hence the thermal performance has to be monitored. | Only functional during current re-circulation, however it works in conjunction with active OLD. This feature is not needed if synchronous rectification is disabled. |
Can be used with other OLD schemes | No | Negative-current OLD and low-current OLD | Active OLD and negative-current OLD | Active OLD and low-current OLD |