VOLTAGE REGULATION STEP-UP CHARGE PUMP DC-DC CONVERTER

S-8821 Series

Seiko Instruments Inc.

9

2. Step-up Charge Pump

The step-up charge pump steps up the voltage by switching ON/OFF of the SW1 to SW4 switching

transistors.

SW4 to ON (charge cycle). Following charging the electricity, in order to discharge the charged

and SW4 to OFF (discharge cycle).

The input voltage can be stepped up to a constant voltage value by repeating this charge cycle and

discharge cycle.

Figure 7 shows the charge cycle, and Figure 8 shows the discharge cycle.

SW 1: OFF

SW 3: OFF

SW 4: ON

SW 2: ON

10

μF

0.10

μF

Current flow

Figure 7

SW 1: ON

SW 3: ON

SW 4: OFF

SW 2: OFF

10

μF

0.10

μF

Current flow

Figure 8