AIC1638 데이터 시트보기 (PDF) - Analog Intergrations

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AIC1638

3-PIN ONE-CELL STEP-UP DC/DC CONVERTER

Analog Intergrations 

turn-on time. Switching frequency depends on load,

input voltage, and inductor value, and it can range up

to 100KHz. The SW on-resistance is typically 1 to 1.5

Ω to minimize switch losses.

When the output voltage drops, the error comparator

enables 100KHz oscillator that turns on the MOSFET

around 7.5us and 2.5µs off time. Turning on the

MOSFET allows inductor current to ramp up, storing

energy in a magnetic field. When MOSFET turns off

that force inductor current through diode to the output

capacitor and load. As the stored energy is depleted,

the current ramp down until the diode turns off. At this

point, inductor may ring due to residual energy and

stray capacitance. The output capacitor stores charge

when current flowing through the diode is high, and

release it when current is low, thereby maintaining a

steady voltage across the load.

As the load increases, the output capacitor discharges

faster and the error comparator initiates cycles sooner,

increasing the switching frequency. The maximum

duty cycle ensure adequate time for energy transfer to

output during the second half each cycle. Depending

on circuit, PFM controller can operate in either

discontinuous mode or continuous conduction mode.

Continuous conduction mode means that the inductor

current does not ramp to zero during each cycle.

VIN

IIN

SW

EXT

Isw

ID

IO UT

+

VO UT

Ico

AIC1638

3-PIN ONE-CELL STEP-UP DC/DC CONVERTER

SPEC NO: DS-1638-00 03/01/00

VEXT

IIN

IPK

ISW

Charge Co.

ID

IOUT

VSW

TDIS Discharge Co.

t

Discontinuous Conduction Mode

VEXT

IIN

ISW

IPK

IV

ID

VSW

IOUT

t

Continuous Conduction Mode

ANALOG INTEGRATIONS CORPORATION

www.analog.com.tw

4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C.

TEL: (8863)577-2500 FAX:(8863)577-2510

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