onsemi CS5171ED8

Overview

CS5171ED8 from ON Semiconductor is a monolithic step-up DC-DC converter IC featuring internal 1.5 A N-channel MOSFET switch, fixed 100 kHz switching frequency, and adjustable output voltage up to 30 V. It operates from 2.7 V to 16 V input, delivers up to 1.5 A peak switch current, and supports applications requiring compact high-efficiency boost conversion in portable instrumentation and industrial sensors.

For engineers reviewing the CS5171ED8 datasheet, pinout, applications, or equivalent options, key selection criteria include its integrated high-side MOSFET, minimum input voltage of 2.7 V, thermal shutdown protection, and ability to regulate outputs above input without external diode-critical for battery-powered systems with tight space constraints.

Technical Context

The CS5171ED8 employs a current-mode PWM control architecture with internal oscillator set to 100 kHz, enabling stable regulation across wide load and line variations. Its error amplifier compares feedback voltage against an internal 1.25 V reference, driving the MOSFET gate via pulse-width modulation.

It integrates over-temperature shutdown, under-voltage lockout (UVLO) with 2.5 V turn-on threshold, and cycle-by-cycle peak current limiting. The device requires only three external components: input capacitor, output capacitor, and feedback resistor divider-enabling minimal BOM count in space-constrained designs.

Key Specifications

Pinout & Package

CS5171ED8 is housed in an 8-pin SOIC package with exposed thermal pad (SOIC-8EP), optimized for thermal dissipation in high-current boost applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS61040DRBT and LT1935ES5#TRMPBF, the CS5171ED8 offers the best balance of integration (internal MOSFET), moderate switching frequency (100 kHz), and robust 1.5 A peak current capability - making it optimal for mid-power boost applications where simplicity and thermal reliability are prioritized over ultra-small size or maximum current.

Availability

CS5171ED8 is available at Aetrix Electronics and suitable for portable medical sensors, industrial process transmitters, and handheld test equipment requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for CS5171ED8 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, and sensor solutions for automotive, industrial, and consumer markets.

The CS5171ED8 belongs to ON Semiconductor's legacy DC-DC converter product line, designed specifically for cost-sensitive, space-constrained boost applications requiring high integration and proven reliability in commercial and industrial environments.

FAQ

What is the maximum output voltage achievable with the CS5171ED8?

The CS5171ED8 supports an adjustable output voltage range from 1.25 V up to 30 V, set by an external resistor divider connected to the FB pin. This is achieved by scaling the feedback voltage to match the internal 1.25 V reference; the upper limit is constrained by the breakdown voltage of the internal MOSFET and external components. For reliable operation, output should remain ≤28 V under worst-case load and temperature conditions to maintain safety margin.

Does the CS5171ED8 require an external Schottky diode?

No, the CS5171ED8 does not require an external Schottky diode because it integrates a high-side N-channel MOSFET switch. Unlike traditional boost controllers, this architecture eliminates the forward voltage drop and associated power loss of a discrete diode, improving efficiency-especially at low output voltages-and simplifying the bill of materials.

What thermal considerations apply to the CS5171ED8 in continuous 1.2 A operation?

In continuous 1.2 A output operation, the CS5171ED8 dissipates approximately 0.8 W at typical 5 V out from 3.3 V in. With its SOIC-8EP package and properly sized copper pour (≥2 cm² on top layer tied to GND), junction temperature remains within safe limits (<125 °C) at +25 °C ambient. Thermal shutdown activates at ~150 °C, providing fail-safe protection if layout or airflow is insufficient.

Can the CS5171ED8 operate from a 2.5 V input source?

No, the CS5171ED8 cannot operate from a 2.5 V input source. Its under-voltage lockout (UVLO) turns the device on only when VIN exceeds 2.5 V (typical), and stable regulation requires ≥2.7 V input per datasheet specifications. At 2.5 V, the IC remains disabled; attempting to force operation risks unstable switching or failure to start.

How is output voltage accuracy affected by resistor tolerance in the feedback divider?

Output voltage accuracy of the CS5171ED8 directly depends on feedback resistor tolerance, as the internal 1.25 V reference has ±1.5% initial accuracy. Using 1% tolerance resistors yields total output error typically within ±3.5%, while 5% resistors may result in ±6.5% deviation. For precision applications, 0.5% resistors and careful layout to minimize parasitic leakage are recommended to maintain regulation integrity.