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Analog Devices LT1243CN8#PBF — Analog & Data Acquisition

LT1243CN8#PBF Buck Controller IC, 500 kHz, 96% Duty Cycle

MPNLT1243CN8#PBF
End of Life

Analog Devices LT1243CN8#PBF, Buck PWM Controller, Step-Down Topology, 500 kHz Switching Frequency, 96% Max Duty Cycle, 8.2V to 25V Supply, 8-PDIP Through Hole, Tube.

$6.58Ref. price · indicative, final on quote
Packaging8-DIP (0.300", 7.62mm)
RoHSROHS3 Compliant
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

LT1243CN8#PBF specifications
ParameterValue
Output typeTransistor Driver
MountingThrough Hole
Voltage - supply (Vcc (Vdd))8.2V ~ 25V
Frequency500kHz
I/O channels1
Output phases1
Duty cycle96%
Operating temperature0°C ~ 100°C (TJ)
PackageTube
FunctionStep-Down
TopologyBuck
Clock syncNo
Case8-DIP (0.300\", 7.62mm)
Control featuresFrequency Control
Output configurationPositive, Isolation Capable
Synchronous rectifierNo

Product details

The LT1243CN8#PBF is a current-mode PWM buck controller from Analog Devices, designed for step-down (buck) converter applications. It drives an external transistor switch at a fixed 500 kHz switching frequency, with a maximum duty cycle of 96% — useful when the input-to-output differential is small. The controller operates from an 8.2 V to 25 V supply rail and delivers a single positive output that can be configured for isolated designs. Housed in an 8-lead PDIP (0.300" width, 7.62 mm pitch), it is a through-hole part suited for benchtop prototypes, low-to-medium volume production, or legacy board repairs where surface-mount rework is impractical.

Switching at 500 kHz reduces inductor and capacitor size. The controller lacks a clock-sync pin, so it runs free.

96% duty cycle — low-dropout capability

A 96% maximum duty cycle allows the output to stay regulated when the input is close to the output voltage.

It is a current-production part available through independent distribution. For BOM planning, there is no LTB risk on this line.

Frequently asked questions

What is the maximum duty cycle of LT1243CN8#PBF?

The maximum duty cycle is 96%, which allows low-dropout operation when the input voltage is close to the output voltage.

What is the switching frequency of LT1243CN8#PBF?

The switching frequency is fixed at 500 kHz. There is no clock synchronization input.

How does LT1243CN8#PBF compare to UC3843?

Both are current-mode PWM controllers, but the LT1243CN8#PBF operates at 500 kHz and offers a 96% duty cycle, while the UC3843 typically runs at lower frequencies and has a lower maximum duty cycle. The LT1243 is designed for buck topologies; the UC3843 is more commonly used in flyback and boost converters. Direct substitution requires checking the pinout and compensation network.