The lowest power consumption mode of the AFE4403 corresponds to the following settings:

• PRF = 62.5 Hz,
• External clock mode (XTALDIS = 1), and
• CLKOUT tri-stated (CLKOUT_TRI = 1).

With the above settings, the currents taken from the supplies are as shown in Table 10-1. The LED driver current is with zero LED current setting.

Enabling the crystal (XTALDIS = 0) leads to an additional power consumption that can be estimated to be approximately equal to (2 × C_sh + 0.5 × C1 + 0.5 × C2) × 0.4 × f_XTAL, where C_sh is the effective shunt capacitance of the crystal, C1 and C2 are the capacitances from the XIN and XOUT pins to ground, and f_XTAL is the frequency of the crystal.

Removing the CLKOUT tri-state leads to an additional power consumption of approximately C_LOAD × V_SUP × f, where V_SUP is the supply voltage of RX_DIG in volts, f = 4 MHz, C_LOAD = the capacitive load on the CLKOUT pin + 2 pF.

The power consumption can be reduced significantly by using the dynamic power-down mode. An illustration of this mode is shown in Table 10-2, where:

• PRF = 62.5 Hz,
• Dynamic power-down is active for 14.7 ms every pulse repetition period,
• All four bits (DYNAMIC[4:1]) are set to 1,
• External clock mode (XTALDIS = 1), and
• CLKOUT is tri-stated (CLKOUT_TRI = 1).