LSF0102-Q1: Sleep mode current consumption

Hi 

The measured current of approximately 25 µA during sleep mode is expected. When VREF_A is at 0 V while the 5-V supply remains available, current flows from the VREF_B/EN bias network through the internal bias FET toward VREF_A. Based on the 200-kΩ bias resistor, the estimated current is approximately:

I_BIAS ≈ (5 V − 0 V − VTH) / 200 kΩ ≈ 21 to 22 µA.

To place the A1/B1 and A2/B2 channels into high-impedance mode, EN must be pulled LOW. However, EN should not normally be driven directly by a push-pull MCU output, because EN and VREF_B form part of the device’s internal bias circuit.

The recommended implementation is:

• Keep EN directly connected to VREF_B.
• Keep the required 200-kΩ resistor from the 5-V supply to the EN/VREF_B node.
• Use an open-drain MCU output or an external open-drain NMOS to pull the EN/VREF_B node LOW during sleep.
• Release the open-drain control when normal operation is required.

Therefore, connecting EN directly to the switched 3.3V_BLE rail is not recommended for normal operation, because EN must be connected to VREF_B to correctly establish the internal FET bias. When EN is LOW, all I/O channels are placed in the high-impedance state.

Brian

Hi Prafulla ,

I would suggest TXU0202 that can minimize the power consumption (2.5uA max at room temp). Thanks.

Brian