MAX1800EHJ Просмотр технического описания (PDF) - Maxim Integrated

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производитель

MAX1800EHJ

Digital Camera Step-Up Power Supply

Maxim Integrated 

Digital Camera Step-Up

Power Supply

Pin Description

PIN

1, 19

2

3

4

5

6

7, 22

8

9

10

11

12

13

14

15

16

17

18

20,

21

23

NAME

PGND

DL1

ON1

FB1

COMP1

DCON1

POUT

DL2

ON2

FB2

COMP2

DCON2

OUT

REF

GND

OSC

FBM

COMPM

LX

RDYM

FUNCTION

Power Ground. Sources of internal N-channel MOSFET power switches. Connect both PGND pins to GND as

close to the IC as possible.

External MOSFET Gate Drive Output for Auxiliary Controller 1. DL1 swings between POUT and GND with

typical 500mA drive current. Connect DL1 to the gate of the external switching N-channel MOSFET for

auxiliary controller 1.

Enable Input for Auxiliary Controller 1. Connect ON1 to POUT to automatically start auxiliary controller 1.

Feedback Input for Auxiliary Controller 1. Connect a feedback resistive voltage-divider from the output to FB1

to set the output voltage. Regulation voltage is VREF (1.25V).

Compensation for Auxiliary Controller 1. Output of transconductance error amplifier. Connect a series resistor

and capacitor to GND to compensate the control loop. See Compensation Design.

Maximum Duty-Cycle Control Input for Auxiliary Controller 1. Connect to POUT to set the default maximum

duty cycle. Connect a resistive voltage-divider from REF to DCON1 to set the maximum duty cycle between

40% and 90%. Pull DCON1 below 400mV to turn the controller off.

Main Power Output. Source of P-channel MOSFET synchronous rectifier switch. Connect both POUT pins

together as close to the IC as possible.

External MOSFET Gate Drive Output for Auxiliary Controller 2. DL2 swings between POUT and GND with

typical 500mA drive current. Connect DL2 to the gate of the external switching N-channel MOSFET for

auxiliary controller 2.

Enable Input for Auxiliary Controller 2. Connect ON2 to POUT to automatically start auxiliary controller 2.

Feedback Input for Auxiliary Controller 2. Connect a feedback resistive voltage-divider from the output to FB2

to set the output voltage. Regulation voltage is VREF (1.25V).

Compensation for Auxiliary Controller 2. Output of transconductance error amplifier. Connect a series resistor

and capacitor to GND to compensate the control loop. See Compensation Design.

Maximum Duty-Cycle Control Input for Auxiliary Controller 2. Connect to POUT to set the default maximum

duty cycle. Connect a resistive voltage-divider from REF to DCON2 to set the maximum duty cycle between

40% and 90%. Pull DCON2 below 400mV to turn the controller off.

Internal Bias Supply Input. Connect to POUT through a resistor, and bypass OUT to GND with a capacitor.

See Compensation Design.

1.250V Reference Output. Bypass REF to GND with a 0.1µF or greater ceramic capacitor.

Analog Ground. Connect GND to PGND at a single point near the IC.

Oscillator Control. Connect a timing capacitor from OSC to GND and a timing resistor from OSC to POUT to

set the switching frequency between 100kHz and 1MHz. See Setting the Switching Frequency.

Main DC/DC Converter Feedback Input. Connect a feedback resistive voltage-divider from POUT to FBM to

set the output voltage. Regulation voltage is VREF (1.25V).

Compensation for Main Controller. Output of transconductance error amplifier. Connect a series resistor and

capacitor to GND to compensate the control loop. See Compensation Design.

Main Power Switching Node. Drains of the internal P-channel and N-channel MOSFET switches. Connect the

LX pins together as close to the IC as possible.

Main Converter Ready Output. An open-drain output sinks current when VFBM < 1.125V, indicating that the

main output is more than 10% out of regulation.

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