LT1309 查看數據表（PDF） - Linear Technology

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LT1309

500kHz Micropower DC/DC Converter for Flash Memory

Linear Technology 

LT1309

TYPICAL PERFORMANCE CHARACTERISTICS

Start-Up Waveforms, ILOAD = 1mA

12V

VOUT

2V/DIV

VPP VALID

10V/DIV

VON/OFF

10V/DIV

50µs/DIV

1309 G08

Start-Up Waveforms, ILOAD = 10mA

VOUT

5V/DIV

IL

500mA/DIV

VON/OFF

10V/DIV

50µs/DIV

1309 G09

Load Transient Response,

COUT = 1µF

12V OUTPUT

1V/DIV

AC COUPLED

60mA

ILOAD

10mA

50µs/DIV

1309 G10

UU U

PI FU CTIO S

SOFT START (Pin 1): A 0.1µF/1MΩ parallel RC from this

pin to GND provides a Soft Start function upon device

turn-on. Initially about 80µA will flow from the pin into the

capacitor. When the voltage at the pin reaches approxi-

mately 0.4V, current ceases flowing out of the pin.

VCC (Pin 2): Input Supply. At least 1µF input bypass

capacitance is required. More capacitance reduces ring-

ing on the supply line.

PGND (Pin 3): Power Ground. Connect to ground plane.

VSW (Pin 4): Collector of Power Switch. High dV/dt

present on this pin. To minimize radiated noise keep

layout short and direct.

GND (Pin 5): Signal Ground. Connect to ground plane.

VPP VALID (Pin 6): This pin provides a logic signal

indicating that output voltage has reached 12V. Active low

with internal 200k pull-up resistor.

SENSE (Pin 7): Output Sense Pin. This pin connects to a

resistive divider that sets the output voltage. In shutdown,

the resistor string is disconnected and current into this pin

reduces to < 1µA.

ON/OFF (Pin 8): Shutdown Control. When pulled below

1.5V, this pin disables the LT1309 and reduces supply

current to 9µA. All circuitry is disabled in shutdown. The

part is enabled when ON/OFF is greater than 1.5V.

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