Analog Devices Inc. AD8240YRMZ-RL

Overview

AD8240YRMZ-RL from Analog Devices is a constant-voltage LED driver/monitor IC designed for automotive lamp control, featuring PWM brightness control (up to 500 Hz), open-LED detection via high-side current-sense amplifier (gain = 24), latch-off overcurrent protection, 12 V regulated output (±1% typical at 25°C), and operation across 9 V to 27 V supply range. It drives external NPN transistors in body control modules for brake/running/turn-signal lamps.

For engineers reviewing the AD8240YRMZ-RL datasheet, AD8240YRMZ-RL pinout, AD8240YRMZ-RL application, or AD8240YRMZ-RL equivalent, key selection criteria include its 8-lead MSOP package, 300 µA operating current, −40°C to +125°C automotive temperature range, VSENSE output impedance of ~10 kΩ, and compatibility with 0.1 Ω–0.5 Ω external shunt resistors for precise current monitoring.

Technical Context

The AD8240YRMZ-RL integrates four functional blocks: a linear regulator (Block A) that sets VO = 12 V using a 5 V reference and resistor divider; a high-side current-sense amplifier (Block B) with 24× gain and ±3% accuracy to detect partial LED failures; a comparator (Block C) that latches off VO when VSENSE exceeds 5 V reference; and an intelligent driver (Block D) that level-shifts PWM input to control external transistor base drive.

It operates as a two-wire (power + ground) solution compatible with existing incandescent wiring harnesses, enabling retrofit into body control ECUs without layout changes. Its linear regulation eliminates EMI concerns and inductor requirements, while the latch-off reset mechanism requires PWM cycling - not a dedicated reset pin - to recover from overcurrent events.

Key Specifications

Pinout & Package

AD8240YRMZ-RL is housed in an 8-lead Mini Small Outline Package (MSOP, RM-8), JEDEC MO-187AA compliant, with 0.65 mm lead pitch and exposed pad for thermal performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED driver/monitor applications.

Compared with MAX16802AATA+T and TLC59284PWR, the AD8240YRMZ-RL uniquely combines constant-voltage regulation, integrated high-side current sensing, and latch-off protection in a single 8-pin MSOP-enabling full lamp monitoring and control with minimal external components and zero changes to legacy two-wire harnesses.

Availability

AD8240YRMZ-RL is available at Aetrix Electronics and suitable for automotive brake lamp control, running lamp regulation, and turn signal monitoring requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD8240YRMZ-RL 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 since 1965.

The AD8240YRMZ-RL belongs to Analog Devices' automotive-grade LED driver/monitor product line, engineered specifically for cost-sensitive, safety-critical exterior lighting applications requiring regulatory-compliant fault detection and seamless integration into existing body control modules.

FAQ

What is the primary function of the AD8240YRMZ-RL in automotive lighting systems?

The AD8240YRMZ-RL serves as a constant-voltage LED driver and monitor that regulates 12 V output for LED strings while providing real-time current sensing via its VSENSE pin. It enables open-LED detection, latch-off overcurrent protection, and PWM-controlled brightness-all within a single 8-lead MSOP package. This allows automotive manufacturers to meet FMVSS 108 and UNECE R6 regulatory requirements without modifying existing two-wire harness architectures.

How does the AD8240YRMZ-RL implement open-LED detection?

The AD8240YRMZ-RL implements open-LED detection using its integrated high-side current-sense amplifier (Block B), which measures voltage across an external shunt resistor and amplifies it by 24× to produce VSENSE. A partial LED failure reduces load current proportionally, causing a corresponding drop in VSENSE (e.g., 25% fewer LEDs → 25% lower VSENSE). This analog output connects directly to a microcontroller ADC or comparator for fault classification without additional signal conditioning.

Can the AD8240YRMZ-RL operate with a supply voltage below 12.5 V?

No-the AD8240YRMZ-RL requires VPLUS ≥ 12.5 V to maintain 12 V regulation at VO. Below this threshold, VO drops linearly with VPLUS due to headroom limitations of the internal linear regulator and external transistor V_BE. The datasheet specifies a minimum VPLUS of 13 V for guaranteed regulation; operation at 9 V–12.4 V results in unregulated, pass-through behavior unsuitable for stable LED driving.

What is the role of the SHUNT pin on the AD8240YRMZ-RL?

The SHUNT pin on the AD8240YRMZ-RL is the high-side input to the internal current-sense amplifier. It connects directly to the positive terminal of the external shunt resistor placed between VO and the LED string. This configuration enables true high-side sensing-decoupling current measurement from chassis ground noise-and allows the AD8240YRMZ-RL to detect open circuits even when multiple lamps share a common ground return path.

Does the AD8240YRMZ-RL require an external 5 V reference, or does it generate one internally?

The AD8240YRMZ-RL does not generate its own 5 V reference; Pin 2 (5V REF) must be driven by an external, stable 5 V reference source. The regulated VO output is derived as VO = (12/5) × V_REF, so VO accuracy directly tracks the precision and stability of the applied reference. Using a ±1% 5 V reference yields ±1% typical VO accuracy at 25°C, as confirmed in Table 1 of the datasheet.