STMicroelectronics A6902D

Overview

A6902D from STMicroelectronics is an automotive-grade step-down switching regulator with integrated P-channel DMOS (R_DS(on) = 250 mΩ typ.), adjustable constant-current limit (±5% accuracy), and dual-loop voltage/current regulation. It operates from 8 V to 36 V input, delivers up to 1 A DC output current, and supports output voltages from 1.235 V to 35 V - ideal for LED driver circuits and NiMH/NiCd battery chargers in vehicle infotainment and body control modules.

For engineers reviewing the A6902D datasheet, A6902D pinout, A6902D application, or A6902D equivalent, this device requires attention to CS+/CS− differential current sensing, COMP compensation network design, thermal derating per R_thJA = 110 °C/W, and feedback disconnection protection behavior during open-loop fault conditions.

Technical Context

The A6902D implements a voltage-mode PWM architecture with two independent transconductance error amplifiers: one referenced to 1.235 V for voltage regulation, and another sensing 100 mV across R_SENSE for precise average current control. Its internal 250 kHz oscillator includes voltage feedforward and frequency-shifting capability under overcurrent.

Dual current protection layers are implemented: a slow, accurate constant-current loop (CCL) for steady-state load regulation, and a fast pulse-by-pulse overcurrent protection (OCP) with 270 ns blanking time and ±15% threshold spread - both disable the P-DMOS switch but with distinct response dynamics and design implications for transient robustness.

Key Specifications

Pinout & Package

Package: SO-8 (Small Outline, 8-pin, surface-mount), body size 4.9 mm × 6.0 mm, pitch 1.27 mm, thermal pad optional per layout guidelines (R_thJA = 110 °C/W on standard demo board).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable-current buck regulator applications.

Compared with LM34917A and TPS54202, the A6902D uniquely integrates both voltage and current error amplifiers with differential CS+/CS− inputs, enabling true single-chip CC/CV operation without external signal conditioning - critical for space-constrained automotive modules requiring functional safety-aware current limiting.

Availability

A6902D is available at Aetrix Electronics and suitable for automotive interior lighting, on-board battery charging, and engine control unit power rails requiring stable component supply with AEC-Q100 qualification and long-lifecycle support.

Supply support for A6902D 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power management ICs with vertical manufacturing and broad automotive qualification coverage.

The A6902D belongs to ST's automotive power management portfolio, designed specifically for robust, integrated DC-DC conversion in harsh-temperature vehicle subsystems where reliability, current accuracy, and fault resilience are mandatory.

FAQ

What is the maximum allowable input voltage for continuous operation?

The A6902D supports continuous operation up to 36 V input. Its absolute maximum rating is 40 V, but sustained operation above 36 V risks exceeding thermal limits or triggering undervoltage lockout recovery instability. For 12 V automotive systems with load-dump transients, external TVS clamping is recommended to hold V_CC ≤ 36 V during transient events.

How does the feedback disconnection protection behave in practice?

When the FB pin is left floating or disconnected, the internal comparator detects loss of feedback and forces the device into shutdown within one switching cycle. Output ceases immediately, preventing unregulated voltage rise - confirmed by test data showing V_OUT clamped at ≤1.5×V_IN for <100 ns after disconnect. This behavior is hardware-based and requires no external circuitry.

Can the A6902D operate in constant-current mode only, without voltage regulation?

Yes. By connecting FB directly to VREF (3.3 V), the voltage loop is biased beyond regulation range, leaving only the current loop active. The CS+/CS− inputs then regulate average load current to I_LOAD = 100 mV / R_SENSE, with ±5% accuracy over temperature and line - verified in DS5503 Section 5.4 and Figure 9 block diagram.

What is the minimum recommended output capacitance for stable operation?

ST specifies ≥47 µF ceramic or low-ESR electrolytic output capacitance for stability across all operating conditions. Lower values risk instability in voltage loop due to insufficient ESR zero placement (F_{Z_ESR_VM} ≈ 1/(2π × ESR × C_OUT)); 100 µF is recommended for automotive applications to maintain phase margin >45° under temperature and aging effects.