MAX1715 Просмотр технического описания (PDF) - Maxim Integrated

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MAX1715

Ultra-High Efficiency, Dual Step-Down Controller for Notebook Computers

Maxim Integrated 

Ultra-High Efficiency, Dual Step-Down

Controller for Notebook Computers

Pin Description

PIN NAME

1

OUT1

2

FB1

3

ILIM1

4

V+

5

TON

6

SKIP

7

PGOOD

8

AGND

9

REF

10

ON1

11

ON2

12

ILIM2

13

FB2

14

OUT2

15, 23,

28

N.C.

FUNCTION

Output Voltage Connection for the OUT1 PWM. Connect directly to the junction of the external inductor and

output filter capacitors. OUT1 senses the output voltage to determine the on-time and also serves as the

feedback input in fixed-output modes.

Feedback Input for OUT1. Connect to AGND for 1.8V fixed output or to VCC for 3.3V fixed output, or connect

to a resistor-divider from OUT1 for an adjustable output.

Current-Limit Threshold Adjustment for OUT1. The LX1-PGND current-limit threshold defaults to +100mV if

ILIM1 is connected to VCC. Or, connect an external resistor to AGND to adjust the limit. A precision 5µA pull-up

current through REXT sets the threshold from 50mV to 200mV. The voltage on the pin is 10 times the current-

limit voltage. Choose REXT equal to 2kΩ per mV of current-limit threshold (100kΩ to 400kΩ).

Battery Voltage Sense Connection. Connect to the input power source. V+ is used only to set the PWM one-

shot timing.

On-Time Selection Control Input. This is a four-level input used to determine DH_ on-time. The TON table

below is for VIN = 24V, VOUT1 = 1.8V, VOUT2 = 2.5V condition.

TON

Frequency (OUT1) (kHz)

Frequency (OUT2) (kHz)

AGND

620

460

REF

485

355

Open

345

255

VCC

235

170

170

Pulse-Skipping Control Input. Connect to VCC for low-noise forced-PWM mode. Connect to AGND to enable

pulse-skipping operation.

Power-Good Open-Drain Output. PGOOD is low when either FB_ input is more than 5.5% below the normal

regulation point (typ).

Analog Ground

+2.0V Reference Voltage Connection. Bypass to AGND with 0.22µF (min) capacitor. Can supply 50µA for

external loads.

OUT1 ON/OFF Control Input. Drive to AGND to turn OUT1 off. Drive to VCC to turn OUT1 on.

OUT2 ON/OFF Control Input. Drive to AGND to turn OUT2 off. Drive to VCC to turn OUT2 on.

Current-Limit Threshold Adjustment for OUT2. The LX2-PGND current-limit threshold defaults to +100mV if

ILIM2 is connected to VCC. Or, connect an external resistor to AGND to adjust the limit. A precision 5µA pull-up

current through REXT sets the threshold from 50mV to 200mV. The voltage on the pin is 10 times the current-

limit voltage. Choose REXT equal to 2kΩ per mV of current-limit threshold (100kΩ to 400kΩ).

Feedback Input for OUT2. Connect to AGND for 2.5V fixed output, or connect to a resistor-divider from

OUT2 for an adjustable output.

Output Voltage Connection for the OUT2 PWM. Connect directly to the junction of the external inductor and

output filter capacitors. OUT2 senses the output voltage to determine the on-time and also serves as the

feedback input in fixed-output mode.

No Connection. These pins are not connected to any internal circuitry. Connect the N.C. pins to the ground

plane to enhance thermal conductivity.

8 _______________________________________________________________________________________

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