NXP Semiconductors MC34674DEPR2

Overview

MC34674DEPR2 from Freescale Semiconductor is a fully integrated single-cell Li-Ion/Li-Polymer battery charger optimized for travel and cradle chargers. It delivers 450 mA constant-current charge with ±0.4% output voltage accuracy at 4.2 V, supports up to 28 V input, and integrates NTC thermistor interface, dual-color LED status indication, and smart battery connection verification for portable consumer electronics.

For engineers reviewing the MC34674DEPR2 datasheet, MC34674DEPR2 pinout, MC34674DEPR2 application, or MC34674DEPR2 equivalent, key selection considerations include factory-programmed 450 mA CC current, 11 V over-voltage protection threshold, thermal foldback at 110°C die temperature, UDFN-EP 2×3 mm package with exposed pad, and compatibility with current-limited AC/DC adapters.

Technical Context

The MC34674DEPR2 implements a three-stage charging profile-trickle (10% of CC), constant-current (450 mA), and constant-voltage (4.2 V)-with end-of-charge detection at 45 mA (10% of I_CHG). Its internal power MOSFET features 450 mΩ typical R_DS(ON) and integrates VIN-BAT comparator with 60 mV offset to prevent reverse leakage.

Charge control logic combines die temperature feedback (110°C thermal limit), NTC interface using V_REF-biased resistor divider (1/3 and 2/3 V_REF thresholds), and safety timers (4.6 hr fast-charge, 0.575 hr trickle-charge). Enable verification requires ≥100 ms stable EN low state, and battery presence is verified via controlled discharge before entering trickle mode.

Key Specifications

Pinout & Package

MC34674DEPR2 is housed in an 8-lead, 2×3 mm² thermally enhanced UDFN package with exposed pad (EPAD) that must be electrically connected to GND and soldered to a large PCB ground plane for effective thermal management.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar single-cell Li-Ion charger applications.

Compared with TPS65023BRSBR and BQ24075RGTR, MC34674DEPR2 offers lower system cost through integration (no external MOSFET/sense resistor), wider input voltage support (28 V), and dedicated NTC interface - making it optimal for cost-sensitive, high-voltage, temperature-aware travel chargers.

Availability

MC34674DEPR2 is available at Aetrix Electronics and suitable for USB-powered travel chargers, smartphone cradle docks, portable medical monitors, and wearable fitness trackers requiring stable component supply and long-term lifecycle support.

Supply support for MC34674DEPR2 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

Freescale Semiconductor (now part of NXP Semiconductors) is a global leader in analog and mixed-signal ICs for power management, automotive, and industrial applications.

The MC34674DEPR2 belongs to Freescale's high-voltage linear battery charger product line, designed specifically for cost-sensitive, compact travel and cradle charger applications requiring robust thermal and overvoltage protection without external discrete components.

FAQ

What is the factory-programmed charge current for MC34674DEPR2?

The MC34674DEPR2 is factory-programmed for a constant-current (CC) charge output of 450 mA, with ±8% tolerance. This value is fixed per device variant and cannot be adjusted externally. The corresponding end-of-charge (EOC) threshold is set to 45 mA (10% of 450 mA), and trickle charge current is 45 mA. These values are confirmed in Table 1 (Device Variations) and Table 4 (Static Electrical Characteristics) of the MC34674 datasheet Rev. 2.0.

Does MC34674DEPR2 support NTC-based temperature monitoring, and how is it configured?

Yes, MC34674DEPR2 supports NTC-based temperature monitoring via dedicated TEMP and VREF pins. VREF supplies a stable bias voltage (~1.2 V), and an external resistor divider with an NTC thermistor generates V_TEMP, which is compared against 1/3 V_REF (over-temperature) and 2/3 V_REF (under-temperature) thresholds. Configuration requires selecting RU and RS values based on NTC resistance at target thresholds (e.g., 0°C and 50°C), as defined in Equations 2 and 3 of the datasheet. No firmware or external ADC is required.

What is the purpose of the exposed pad (EPAD) on MC34674DEPR2, and how must it be handled in layout?

The EPAD on MC34674DEPR2 is an exposed thermal pad that must be electrically connected to GND and soldered to a large PCB ground plane to ensure effective thermal dissipation. Per datasheet Section "PIN CONNECTIONS", failure to connect the EPAD to GND compromises thermal performance and may cause premature thermal shutdown. The device specifies R_θJA = 70°C/W under JEDEC test conditions, achievable only with proper EPAD grounding and copper area - not optional for sustained 450 mA operation.

How does MC34674DEPR2 verify battery presence before initiating charge?

MC34674DEPR2 performs automatic battery connection verification by applying a controlled discharge pulse (6 mA typical) through the BAT pin for 0.5 seconds after enable confirmation. If battery voltage remains stable, charging proceeds to trickle mode; if voltage collapses, the device enters a fault state with yellow LED blink (0.5 Hz). This method avoids false triggers from parasitic capacitance and eliminates need for external detection circuitry - a core feature confirmed in Functional Description Section "BATTERY CONNECTION VERIFICATION".

What overvoltage protection features does MC34674DEPR2 provide, and what is the trip threshold?

MC34674DEPR2 provides input overvoltage protection (OVP) with a typical trip threshold of 11 V (range: 10–12 V), as specified in Table 4. When VIN exceeds this threshold, charging halts immediately, the BAT output is disabled, and the dual-color LED indicates fault via yellow blink. Recovery occurs automatically once VIN falls below the hysteresis level (VOVPHYS = 400 mV), resetting internal logic. This protects downstream circuitry from AC/DC adapter failures - a key differentiator versus chargers lacking integrated OVP.