LT1074 データシートの表示（PDF） - Linear Technology

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LT1074

Step-Down Switching Regulator

Linear Technology 

LT1074/LT1076

ELECTRICAL CHARACTERISTICS

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.

Note 2: To calculate maximum switch “on” voltage at currents between

low and high conditions, a linear interpolation may be used.

Note 3: A feedback pin voltage (VFB) of 2.5V forces the VC pin to its low

clamp level and the switch duty cycle to zero. This approximates the zero

load condition where duty cycle approaches zero.

Note 4: Total voltage from VIN pin to ground pin must be ≥ 8V after start-

up for proper regulation.

Note 5: Switch frequency is internally scaled down when the feedback pin

voltage is less than 1.3V to avoid extremely short switch on times. During

testing, VFB is adjusted to give a minimum switch on time of 1µs.

Note

6:

ILIM

≈

RLIM –

2k

1k

(LT1074),

ILIM ≈

RLIM – 1k

5.5k

(LT1076).

Note 7: Switch to input voltage limitation must also be observed.

Note 8: VMAX = 40V for the LT1074/76 and 60V for the LT1074HV/76HV.

Note 9: Does not include switch leakage.

BLOCK DIAGRA

INPUT SUPPLY

LT1074

10µ A

0.3V

+

µ-POWER

SHUTDOWN

–

6V

REGULATOR

AND BIAS

320 µA

6V TO ALL

CIRCUITRY

2.35V

+

CURRENT

LIMIT

SHUTDOWN

500 Ω

CURRENT

LIMIT

COMP

+

0.04

C2

–

250 Ω

–

SHUTDOWN*

I LIM*

4.5V 10k

4

2.21V

+

A1

ERROR

AMP

–

FREQ SHIFT

100kHz

OSCILLATOR

SYNC

3V(p-p)

R

S

R/S

LATCH

Q

G1

R

VIN

Z

ANALOG

X

MULTIPLIER

XY

Z

Y

+

C1

–

PULSE WIDTH

COMPARATOR

FB

VC

24V (EQUIVALENT)

LT1076

*AVAILABLE ON PACKAGES WITH PIN

COUNTS GREATER THAN 5.

0.1 Ω

400 Ω 15 Ω

SWITCH

OUTPUT

(VSW)

100Ω

SWITCH

OUTPUT (VSW )

LT1074 • BD01

1074fd

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