Analog Devices Inc. ADP1108AR-5

Overview

ADP1108AR-5 from Analog Devices is a micropower step-up/step-down DC-DC converter IC with fixed 5 V output, internal 1 A power switch, programmable current limit, and auxiliary gain block for low-battery detection. It operates from 2.0 V to 30 V input, delivers up to 300 mA at 5 V in step-down mode from 9 V input, and consumes only 90 µA quiescent current. Used in portable instruments and battery-backed peripherals.

For engineers reviewing the ADP1108AR-5 datasheet, ADP1108AR-5 pinout, ADP1108AR-5 application, or ADP1108AR-5 equivalent, key selection criteria include its dual-mode topology support, 5 V ±5% output accuracy, SO-8 package compatibility, and integrated comparator for under-voltage lockout or post-regulation functions.

Technical Context

The ADP1108AR-5 implements a gated-oscillator control architecture with 19 kHz typical switching frequency and 36 µs fixed on-time, enabling stable regulation without external compensation. Its dual-access power switch (SW1 collector, SW2 emitter) allows reconfigurable step-up or step-down topologies using only three external components.

Internal circuitry includes a precision 1.245 V reference, hysteresis-enabled feedback comparator (±5 mV trip tolerance), and an uncommitted gain block (AV = 400–1000 V/V) with open-collector AO output capable of sinking 100 µA - usable as low-battery detector or linear post-regulator.

Key Specifications

Pinout & Package

ADP1108AR-5 is housed in an 8-pin SOIC (SO-8) package with standard 1.27 mm pitch, JEDEC MS-012AC compliant, and RoHS-compliant lead finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DC-DC converter applications.

Compared with TPS61040DRBT and LT1931ES5#TRMPBF, ADP1108AR-5 offers unique dual-mode flexibility, lower IQ (90 µA vs. >500 µA), and on-chip functional blocks (AO/SET) that eliminate discrete comparators - critical for cost-sensitive, battery-powered systems requiring both voltage conversion and system supervision.

Availability

ADP1108AR-5 is available at Aetrix Electronics and suitable for handheld test equipment, industrial sensor nodes, medical point-of-care devices, and legacy peripherals requiring stable component supply with long-term manufacturability.

Supply support for ADP1108AR-5 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The ADP1108 product line was designed for ultra-low-power, multi-topology DC-DC conversion in space-constrained, battery-operated systems - emphasizing minimal external components, extended runtime, and integrated supervision functions.

FAQ

What is the guaranteed output voltage accuracy of the ADP1108AR-5 across temperature and load?

The ADP1108AR-5 guarantees a 5.00 V output within ±5% (4.75 V to 5.25 V) over the full operating temperature range (0°C to +70°C) and under all specified load conditions. This accuracy is achieved via on-die laser-trimmed resistors that set the feedback ratio, ensuring consistent regulation without external calibration. The ADP1108AR-5 maintains this specification even with input voltage variations from 2.0 V to 30 V in applicable topologies.

Can the ADP1108AR-5 be used in step-down (buck) configuration, and what are the input limits?

Yes, the ADP1108AR-5 supports step-down operation with input voltages up to 30 V, making it suitable for converting 9 V, 12 V, or 24 V rails to 5 V. In buck mode, the internal NPN switch operates with emitter-driven topology, and maximum switch current is limited to 650 mA. The ADP1108AR-5 datasheet confirms 300 mA delivery at 5 V from a 9 V input, and recommends using the ILIM pin to constrain peak current when input voltage exceeds 12 V.

How does the auxiliary gain block (SET/AO pins) function in the ADP1108AR-5?

The ADP1108AR-5's auxiliary gain block uses the SET pin as a non-inverting input referenced to the internal 1.245 V bandgap, with AO providing an open-collector NPN output sinking up to 100 µA. When a resistor divider from VIN to GND is connected to SET, AO asserts low upon crossing a user-defined threshold - enabling low-battery detection, under-voltage lockout, or error amplification. This eliminates the need for external comparators in supervisory functions.

What is the purpose of the ILIM pin on the ADP1108AR-5, and how is it configured?

The ILIM pin on the ADP1108AR-5 programs the peak switch current limit by connecting a resistor between ILIM and VIN. With no resistor (ILIM tied directly to VIN), the ADP1108AR-5 defaults to ~500 mA limit. A 220 Ω resistor reduces the limit to 400 mA. This feature protects the internal switch and external magnetics during overload or short-circuit events, and improves thermal performance in high-input-voltage step-down applications.

Is the ADP1108AR-5 compatible with standard SO-8 footprints, and what are its thermal limitations?

Yes, the ADP1108AR-5 uses a standard JEDEC MS-012AC SO-8 package with 1.27 mm lead pitch and RoHS-compliant finish, ensuring drop-in compatibility with common SO-8 land patterns. Its maximum power dissipation is 500 mW, and thermal resistance θJA is 160°C/W (typical). For continuous 300 mA output at 5 V in step-down mode, PCB copper area and airflow must maintain junction temperature below +125°C - verified via the ADP1108AR-5's absolute maximum rating of 0°C to +70°C ambient operation.