Analog Devices Inc. LT1161ISW#PBF

Overview

LT1161ISW#PBF from Analog Devices (formerly Linear Technology) is a quad protected high-side N-channel MOSFET driver IC designed for industrial, avionics, and automotive power switching applications. It features four independent channels, each with an integrated charge pump (750 kHz), individual short-circuit protection, programmable current limit (50–80 mV threshold), automatic restart timers, and voltage-limited gate drive (up to 12 V above V+). It operates from 8 V to 48 V supply and withstands –15 V to 60 V transients.

For engineers reviewing the LT1161ISW#PBF datasheet, LT1161ISW#PBF pinout, LT1161ISW#PBF application, or LT1161ISW#PBF equivalent, key selection considerations include its flowthrough pinout, self-contained gate drive per channel, drain-sense-based fault detection, Kelvin-connected V+ pins for accurate current sensing, and compatibility with logic-level MOSFETs down to 8 V operation.

Technical Context

The LT1161ISW#PBF implements four fully independent high-side switch channels, each integrating a self-contained 750 kHz charge pump to generate gate voltage up to 12 V above V+, enabling full enhancement of standard or logic-level N-channel MOSFETs without external components. Each channel includes a supply-referenced drain sense comparator with 65 mV nominal threshold (±15 mV) and +0.33%/°C TC, matched to copper PCB shunt temperature drift.

Protection logic is per-channel: when sense voltage exceeds threshold, the gate is pulled low within 25–50 µs, the timer pin is discharged, and a 14 µA current source recharges an external CT capacitor to 3 V to initiate automatic restart. Input pins feature TTL/CMOS-compatible thresholds (1.4 V typical), 200 mV hysteresis, and internal 75 kΩ pull-downs; timer pins default high via 14 µA pull-up.

Key Specifications

Pinout & Package

LT1161ISW#PBF is housed in a 20-lead plastic SO wide (SW) package with gull-wing leads, optimized for surface-mount assembly and thermal performance (θ_JA = 110°C/W). The flowthrough pinout minimizes PCB routing complexity and supports Kelvin connection of V+ pins for accurate current sensing.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-side MOSFET driver applications.

Compared with LT1161ISW#PBF, LT1910CS8#TRPBF trades quad integration and CT-programmable timing for smaller footprint and simpler fault signaling, while TPS2H160-Q1 replaces analog per-channel configurability with digital diagnostics and automotive qualification - making LT1161ISW#PBF optimal for cost-sensitive, multi-channel industrial designs requiring field-tunable protection behavior.

Availability

LT1161ISW#PBF is available at Aetrix Electronics and suitable for industrial control, avionics power distribution, and automotive solenoid driving applications requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for LT1161ISW#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices acquired Linear Technology in 2017 and maintains full product support, datasheet archives, and application engineering for legacy Linear parts including the LT1161 family.

The LT1161 belongs to Linear's protected high-side driver product line, engineered specifically for harsh-environment power switching where supply transients, thermal stress, and reliability under fault conditions are critical design constraints.

FAQ

What is the maximum supply voltage the LT1161ISW#PBF can withstand without damage?

The LT1161ISW#PBF is 100% tested and guaranteed to survive supply transients from –15 V to +60 V applied between V+ and GND pins. Exceeding +60 V - even for microseconds - risks catastrophic failure. Local decoupling at the V+ pins and use of ferrite beads are recommended for transient suppression in automotive or industrial settings where load-dump events occur.

How does the LT1161ISW#PBF achieve accurate current limiting with PCB trace shunts?

The LT1161ISW#PBF uses a supply-referenced drain sense comparator with a 65 mV nominal threshold and +0.33%/°C temperature coefficient, closely matching the +0.39%/°C TC of 1 oz. copper PCB traces. When V+ pins are connected directly to the shunt's high side (Kelvin connection), this alignment enables near-zero-drift current sensing - allowing precise trip points (e.g., 2.5 A with 0.02 Ω) without calibration.

Can the LT1161ISW#PBF drive standard N-channel MOSFETs from an 8 V supply?

At 8 V supply, the LT1161ISW#PBF's charge pump delivers only ~4–6 V above V+, which is insufficient to fully enhance most standard N-channel MOSFETs (typically requiring ≥10 V V_GS). However, it can reliably drive logic-level MOSFETs with V_GS(th) ≤ 2.5 V and V_GS(max) ≥ 15 V - such as the IRFZ34 or MTD3055EL - enabling full enhancement down to 8 V operation.

What is the purpose of the dual V+ pins (11 and 20) on the LT1161ISW#PBF?

Both V+ pins (11 and 20) are internally connected and must be externally tied together. They serve a dual role: supplying operating current to the IC and acting as the high-side reference for all four drain sense comparators. Connecting them directly to the positive side of each external sense resistor establishes a Kelvin sense path - eliminating IR drop error and ensuring accurate, stable current-limit thresholds across temperature and load conditions.

How is automatic restart disabled on the LT1161ISW#PBF for latched-off operation?

To disable automatic restart and implement latched-off behavior, connect a resistor (e.g., 2 kΩ) between the IN and TIMER pins of the affected channel. This forms an SCR-like latch: when a fault pulls the TIMER pin low, the resistor sustains enough current to hold the timer node low until the IN signal is cycled off and back on. This configuration is commonly used in safety-critical circuits where manual reset is required after overcurrent.