Rainbow-electronics MAX1709 Manual de usuario descargar pdf (Pagina 7)

MAX1709

4A, Low-Noise, High-Frequency,

Step-Up DC-DC Converter

_______________________________________________________________________________________ 7

SHUTDOWN WITH SOFT-START

= 0.01µF)

MAX1709-17

1ms/div

OUT

2V/div

ONA

5V/div

2A/div

= 0.01µF

OUT

= 5Ω

ONB

= V

OUT

SHUTDOWN WITHOUT SOFT-START

MAX1709-18

1ms/div

OUT

2V/div

ONA

5V/div

2A/div

= 0

OUT

= 5Ω

ONB

= V

OUT

Typical Operating Characteristics (continued)

(Circuit of Figure 1, T

= +25°C, unless otherwise noted.)

Pin Description

PIN NAME FUNCTION

1 ONA On-Control Input. When ONA = high or ONB = low, the device turns on (Table 1).

2, 3, 4 LX

Drain of N-Channel Power Switch. Connect pins 2, 3, and 4 together. Connect external

Schottky diode from LX to OUT.

5, 8 GND Ground

6 SS/LIM

Soft-Start and/or Current-Limit Input. Connect a capacitor from SS/LIM to GND to control the

rate at which the device reaches current limit (soft-start). To reduce the current limit from the

preset values, connect a resistor from SS/LIM to GND (see Design Procedure). During

shutdown, this pin is internally pulled to GND to discharge the soft-start capacitor.

7 REF

1.26V Voltage Reference Output. Bypass with a 0.22µF capacitor to GND. Maximum REF load

is 50µA.

9 OUT

Output Voltage Sense Input. The device is powered from OUT. Bypass with a 0.1µF to PGND

with less than 5mm trace length. Connect a 2Ω series resistor from the output filter capacitor to

OUT (Figure 1).

10 FB

DC-DC Converter Feedback Input. Connect FB to GND for internally set output voltage (see

3.3/5 pin description). Connect a resistor-divider from the output to set the output voltage in

the +2.5V to +5.5V range. FB regulates to +1.25V (Figure 4).

11, 12, 13 PGND Power Ground, Source of N-Channel Power MOSFET Switch

14 3.3/5

Output Voltage Selection Pin. When FB is connected to GND, the regulator uses internal

feedback to set the output voltage. 3.3/5 = low sets output to 3.3V; 3.3/5 = high sets output to

5V. If an external divider is used at FB, connect 3.3/5 to ground.

15 CLK

Clock Input for the DC-DC Converter. Connect to OUT for internal oscillator. Optionally, drive

with an external clock for external synchronization.

16 ONB Shutdown Input. When ONB = high and ONA = low, the device turns off (Table 1).

1 2 3 4 5 6 7 8 9 10 11 12

Step-Up DC-DC Converter 1

Comentarios a estos manuales

Sin comentarios

Rainbow-electronics MAX1709 Manual de usuario Pagina 7

Comentarios a estos manuales

Relacionado con productos y manuales para Sensores Rainbow-electronics MAX1709