Rainbow-electronics MAX1730 Instrukcja Użytkownika Pobierz pdf (Strona 7)

To maximize efficiency, the MAX1730 automatically

switches between charge-pump configurations (Figures

1, 2, and 3). Efficiency is greatest when the IN/OUT volt-

age ratio is close to the voltage ratio of the selected

capacitor configuration and decreases for output volt-

ages lower than the divider ratio. To choose between

configurations, the MAX1730 senses the input voltage

and the output voltage. The MAX1730 uses a control

scheme with hysteresis to prevent oscillation between

capacitor configurations.

Applications Information

Setting the Output Voltage

For an output voltage of 1.8V, connect FB to GND. For

an output voltage of 1.9V, connect FB to IN.

MAX1730

50mA Regulated Step-Down Charge Pump

for 1.8V or 1.9V Logic

_______________________________________________________________________________________ 7

NOTE: SWITCH STATES SET FOR STAGE 1.

ALL SWITCHES REVERSE STATE FOR STAGE 2.

OUT

C1 C2

OUT

= V

Figure 1. 1:1 Capacitor Configuration

C1 C2

OUT

= V

NOTE: SWITCH STATES SET FOR STAGE 1.

ALL SWITCHES REVERSE STATE FOR STAGE 2.

Figure 2. 3:2 Capacitor Configuration

OUT

= V

NOTE: SWITCH STATES SET FOR STAGE 1.

ALL SWITCHES REVERSE STATE FOR STAGE 2.

Figure 3. 2:1 Capacitor Configuration

1 2 3 4 5 6 7 8

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Rainbow-electronics MAX1730 Instrukcja Użytkownika Strona 7