NXP Semiconductors MC34844EP

Overview

MC34844EP from NXP Semiconductors (formerly Freescale) is a 10-channel SMARTMOS LED backlight driver with integrated 2.5 A boost converter, designed for LCD displays from 10" to 20"+. It operates from 7.0–28 V input, drives up to 160 LEDs across 10 parallel strings with ±2% current matching, supports 256-level I²C-programmable PWM dimming, and delivers up to 90% boost efficiency. It is used in HDTV, notebook, and GPS display backlighting systems.

For engineers reviewing the MC34844EP datasheet, MC34844EP pinout, MC34844EP application, or MC34844EP equivalent, key selection considerations include its 32-pin TQFN package, programmable boost switching frequency (160–1300 kHz), dual analog dimming inputs (PIN/NIN), integrated overtemperature/overvoltage/LED open-short protection, and master/slave synchronization capability via CK/M/~S pins.

Technical Context

The MC34844EP integrates a non-synchronous boost controller with Dynamic Headroom Control (DHC) that senses LED string voltage and dynamically adjusts VOUT to the minimum required level-reducing power loss and improving efficiency. Its 10-channel current mirror uses matched internal transistors and external ISET resistor programming to maintain ±2% channel-to-channel current accuracy across temperature and supply variations.

It supports three operating modes: Manual (EN-controlled), SM Bus (bus-activated with watchdog), and I²C (full register control with sleep/shutdown states). The device implements hardware OVP via A0/SEN pin (6.5 V threshold) and software-configurable OVP register (11–62 V in ~4 V steps), plus optical/temperature closed-loop dimming support.

Key Specifications

Pinout & Package

MC34844EP is housed in a 32-lead, 5 mm × 5 mm × 1.0 mm thermally enhanced TQFN package with exposed pad (EP) for thermal dissipation. Pin pitch is 0.5 mm. Package meets Pb-free (RoHS-compliant) requirements per EP suffix.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM3409QMH/NOPB and TPS61165DRVR, the MC34844EP uniquely integrates 10-channel matched current sinks, DHC, programmable OVP, and master/slave synchronization-making it the only solution qualified for medium-format LCD backlighting requiring uniformity, efficiency, and system-level timing coordination.

Availability

MC34844EP is available at Aetrix Electronics and suitable for monitor backlighting, HDTV panel design, and portable display development requiring stable component supply and long-term industrial availability.

Supply support for MC34844EP 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

NXP Semiconductors acquired Freescale in 2015 and maintains full technical support, documentation, and product continuity for the MC34844EP family.

The MC34844EP belongs to NXP's SMARTMOS analog power management portfolio, engineered specifically for high-reliability LCD backlighting in consumer, industrial, and automotive display systems.

FAQ

What is the maximum LED string voltage supported by the MC34844EP?

The MC34844EP supports up to 60 V on the VOUT pin, with programmable overvoltage protection ranging from 11 V to 62 V in ~4 V increments via the OVP register. Hardware OVP can also be set using a resistor divider or zener diode on the A0/SEN pin, with a fixed 6.5 V threshold. This allows safe operation with up to ~16 white LEDs (3.6 V each) in series per string under typical conditions. The MC34844EP's Dynamic Headroom Control ensures VOUT tracks actual string voltage to minimize excess headroom.

How does the MC34844EP achieve ±2% current matching across its 10 channels?

The MC34844EP achieves ±2% current matching through a precision 10-channel current mirror architecture with laser-trimmed internal transistors and matched layout. Each channel shares a common reference established by the ISET resistor, and the matching is guaranteed over -40°C to +105°C ambient temperature and 7–28 V input voltage. No external calibration or per-channel feedback is required-the MC34844EP maintains this accuracy inherently via its SMARTMOS process and on-die matching design.

Can the MC34844EP operate without an I²C interface?

Yes, the MC34844EP supports Manual mode operation without I²C. In this mode, SCK and SDA pins are tied low, and control is handled via EN (enable), PWM (external dimming signal), and analog inputs PIN/NIN. The device retains full functionality-including boost regulation, current sinking, fault reporting via FAIL pin, and OVP-without any I²C communication. This makes the MC34844EP suitable for cost-sensitive or microcontroller-limited designs where register-level configuration is unnecessary.

What thermal management provisions does the MC34844EP include?

The MC34844EP integrates overtemperature protection (OTP) with a 150°C trip point and 25°C hysteresis, and supports optical/temperature closed-loop dimming via the TEMP/OPTO interface. Its 32-pin TQFN package features an exposed thermal pad (EP) that must be soldered to a large copper pour for effective heat dissipation. Thermal resistance is specified as θ_JA = 32°C/W and θ_JC = 3.5°C/W, enabling reliable operation up to 105°C ambient when properly mounted. The MC34844EP also reduces thermal load via Dynamic Headroom Control and 90% peak boost efficiency.

How is synchronization implemented across multiple MC34844EP devices?

Multiple MC34844EP devices are synchronized using the CK (clock) and M/~S (master/slave) pins. One device is configured as Master (M/~S = high), outputting its internal PWM clock on CK; others are set as Slaves (M/~S = low), accepting that clock on their CK pins. This ensures identical dimming timing and phase alignment across all units-critical for multi-zone backlighting. The MC34844EP supports slave-mode acquisition times from 50 ms (at 27 kHz) to 2 s (at 110 Hz), ensuring robust lock under variable conditions.