My customer is having a problem with the TPS2410 (see attached schematic).
The ideal diode functions as expected and is used as a bidirectional current control.
The 12V bus is connected to the C pin as per page 22 of the spec sheet (Bidirectional control and blocking).
The issue with the device is when the ideal diode is disabled.
Signal BBU_ENABLE_L is active low, 12V bus goes low and VBAT1 (battery voltage) is 15-20V.
No power can be pulled from the battery but a voltage is measured on the 12V bus in the order of 3V.
The customer is monitoring the 12V bus. If there is a voltage, the host assumes the 12V bus is ok.
What can be accomplished to remove this voltage on the 12V bus?
The voltage is leaking from the resistance between the a and C pins on the controller.
Here are testing results. The C-pin current is way outside of specification. The total current is not accounted for (IN = OUT). It appears that Vac ~= -1.8V is a threshold for sourcing/draining current from the A-pin.
Test Name | C-Voltage (V) | A-Voltage (V) | A-Pin current (uA) | C-Pin Current (uA) | GND-Pin Current (uA) | Comment | Voltage Delta (External - Cell) (V) |
Minimum PS-V #1 | 11.64 | 7.2 | -530 |
|
| A pin charges the cell stack | 4.44 |
Minimum PS-V #2 | 10.11 | 77 |
|
| A pin discharges the cell stack | 1.53 | |
Minimum PS-V #3 | 10.44 | 176 |
|
| A pin discharges the cell stack | 1.20 | |
Minimum PS-V #4 | 10.65 | 245 |
|
| A pin discharges the cell stack | 0.99 | |
Nominal PS-V #1 | 12.20 | 7.2 | -566 | 1225 | 3074 | A pin charges the cell stack | 5.00 |
Nominal PS-V #2 | 10.11 | -88 | 1225 | 2999 | A pin charges the cell stack | 2.09 | |
Nominal PS-V #3 | 10.44 | 12 | 1225 | 2985 | A pin discharges the cell stack | 1.76 | |
Nominal PS-V #4 | 10.65 | 88 | 1225 | 2977 | A pin discharges the cell stack | 1.55 | |
Maximum PS-V #1 | 12.36 | 7.2 | -570 |
|
| A pin charges the cell stack | 5.16 |
Maximum PS-V #2 | 10.11 | -135 |
|
| A pin charges the cell stack | 2.25 | |
Maximum PS-V #3 | 10.44 | -36 |
|
| A pin charges the cell stack | 1.92 | |
Maximum PS-V #4 | 10.65 | 28 |
|
| A pin discharges the cell stack | 1.71 |