13.16.1 Charge Pump

An unregulated charge pump is utilized to boost the input to the V_BOOT voltage regulator during low input supply voltage conditions. When the HV_DD supply voltage drops below the CP_START voltage, the charge pump is activated. When activated, 2 x HVDD is presented to the input of the VBOOT regulator. The charge pump is capable of maintaining a VB_OOT output of +9V @ 15 mA for a HV_DD supply voltage of 5.25V to 7V. The charge pump is capable of maintaining a V_BOOT output of +12V @ 20 mA for a supply input voltage of 7V to 13.5V. The charge pump is disabled and bypassed at HV_DD voltages above 13.5V, allowing an output voltage of +12V @ 30 mA.

The charge pump requires a capacitor between pins, CAP1 and CAP2. A typical charge pump capacitor should be a 0.1 μF to 1 μF ceramic capacitor.