onsemi CS5174GDR8

Overview

CS5174GDR8 from onsemi is a 560 kHz, negative-feedback switching boost regulator with integrated 1.5 A NPN power switch, operating from 2.7 V to 30 V input and regulating negative output voltages referenced to −2.45 V at the NFB pin. It employs current-mode control, supports flyback/SEPIC/inverting topologies, and includes thermal shutdown, frequency foldback, and external synchronization.

For engineers reviewing the CS5174GDR8 datasheet, pinout, applications, or equivalent options, this page delivers verified functional identity, SOIC-8 package mapping, confirmed −2.45 V NFB reference, 560 kHz base frequency, thermal shutdown at 150°C, and pin-to-pin alternatives to LT1373 - all extracted from onsemi's official Rev. 23 datasheet.

Technical Context

The CS5174GDR8 implements current-mode control using an internal ramp derived from switch current, combined with oscillator-generated slope compensation to prevent subharmonic oscillation above 50% duty cycle. Its dual-path error amplifier accepts negative feedback via the NFB pin (−2.45 V reference) and drives the VC pin for loop compensation and current limit control.

Switching is governed by a trimmed 560 kHz oscillator (±18% accuracy), with frequency foldback triggered when NFB exceeds −0.65 V - reducing frequency to ~112 kHz during overload. The integrated 1.5 A NPN switch features 63 mΩ emitter sensing, 40 V V_SW rating, and thermal shutdown with 25°C hysteresis.

Key Specifications

Pinout & Package

CS5174GDR8 is housed in an SOIC-8 (Case 751) package with exposed pad for thermal enhancement. Pin 1 is VC (loop compensation), Pin 2 is NFB (negative feedback input), Pin 3 is Test (must be grounded or floating), Pin 4 is SS (sync/shutdown), Pin 5 is V_CC (power input), Pin 6 is AGND (analog ground), Pin 7 is PGND (power ground), and Pin 8 is V_SW (switch collector).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar switching regulator applications.

Compared with CS5174GDR8, LT1373CS8#PBF offers higher current headroom and voltage margin but shares identical footprint and control architecture, while TPS61085DGQR demands redesign for negative output generation and lacks NFB-based regulation precision.

Availability

CS5174GDR8 is available at Aetrix Electronics and suitable for industrial sensor power supplies, portable medical instrumentation, automotive display bias, and PLC analog I/O modules requiring stable component supply across extended temperature and input voltage ranges.

Supply support for CS5174GDR8 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

onsemi is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The CS517x family was designed specifically for compact, high-efficiency DC-DC conversion in space- and cost-constrained systems requiring flexible topology support - especially where negative voltage rails or wide input ranges are critical.

FAQ

What is the exact NFB reference voltage for CS5174GDR8, and how does it affect output regulation?

The CS5174GDR8 has a confirmed NFB reference voltage of −2.45 V (typical), with min/max of −2.55 V and −2.35 V across temperature. This sets the regulation point for negative output voltages: for example, a −12 V output requires R1/R2 = 3.9 per V_OUT = −2.5 × (R1+R2)/R2. The tight 100 mV tolerance ensures <1% output error before resistor tolerances, making CS5174GDR8 suitable for precision analog bias rails.

Can CS5174GDR8 be used in flyback topology, and what design considerations apply?

Yes, CS5174GDR8 supports flyback configuration per its datasheet - it is explicitly listed among supported topologies. Key considerations include referencing the NFB pin to the secondary-side ground, selecting transformer turns ratio to keep V_SW ≤40 V under worst-case input and load, and using frequency foldback (triggered at −0.65 V on NFB) to protect components during startup or short-circuit events. The current-mode architecture inherently stabilizes flyback operation without additional slope compensation.

What is the maximum allowable VSW voltage, and how is it enforced in boost applications?

The absolute maximum V_SW rating for CS5174GDR8 is 40 V, as specified in the Maximum Ratings table. In boost topology, V_SW(max) = V_OUT(max) + V_F, where V_F is the output diode forward voltage (e.g., 0.5 V for Schottky). Therefore, for a −12 V output, V_SW reaches +12.5 V - well within limit. Exceeding 40 V risks permanent damage; external TVS clamping is recommended if transformer leakage or layout parasitics could cause overshoot.

How does the CS5174GDR8 implement current limiting, and can it be adjusted externally?

CS5174GDR8 limits peak switch current via internal sensing of the 63 mΩ emitter resistor and clamping the VC pin voltage. The nominal 1.5 A limit corresponds to VC ≈ 1.05 V. To reduce current limit, an external shunt (e.g., Zener or diode) between VC and AGND lowers the clamp voltage - e.g., clamping VC at 0.8 V reduces limit to ~1.2 A. This adjustment is validated in the datasheet's "Reducing the Current Limit" section and requires no additional components beyond the clamp element.

Is CS5174GDR8 pin-to-pin compatible with LT1373, and what are the key functional equivalences?

Yes, CS5174GDR8 is explicitly stated as pin-to-pin compatible with LT1373 in the datasheet's Features list. Both share identical SOIC-8 pinout, 560 kHz base frequency, −2.5 V NFB reference, sync/shutdown functionality on Pin 4, and current-mode control architecture. Differences include CS5174GDR8's lower max V_SW (40 V vs. 60 V) and slightly tighter NFB reference tolerance (±100 mV vs. ±150 mV), making them direct drop-in replacements in most negative-output designs.