[4] LOADSW/LDO: LDO startup causes reset

nPM1304 Engineering A Errata

This anomaly applies to Engineering A, build codes CAAA-AA0, QEAA-AA0.

Symptoms

The device resets at LDO startup due to voltage drop on VBAT.

Conditions

LOADSW1/LDO1 or LOADSW2/LDO2 starts up in LDO mode.

Consequences

Power fail comparator (POF) triggers a reset of the device.

Workaround

Apply the following workaround:

  1. Connect LOADSW and LDO in series as shown in the following figure:

    Connect LOADSW and LDO in series

  2. Configure LOADSW1/LDO1 as a load switch and LOADSW2/LDO2 as an LDO.
  3. Start up LDO2.
  4. Use LOADSW1 to enable or disable VOUTLDO2 output.

The workaround causes an overshoot on VOUTLDO2. The overshoot increases with lower temperatures and lower output voltages. Typical peak voltages are described in the following table:

Table 1. Typical peak voltages at startup
Output voltage (V) Temperature (°C) Typical peak voltage (V)
1.0 -40 1.35
1.0 25 1.29
1.8 -40 1.91
1.8 25 1.83

For alternative workaround options, contact technical support at Nordic Semiconductor.

Note: This workaround allows the use of only one LDO.

A drop-in compatible fix for this anomaly is targeted for revision 2 of the nPM1304 in Q1 2026.