NXP Semiconductors MC34702EK

Overview

MC34702EK from Freescale Semiconductor is a dual-output power management IC integrating a 3.0A synchronous buck switch-mode regulator for microprocessor core supply and an external-NMOS LDO controller for I/O/bus voltage regulation. It operates from 2.8V to 6.0V input, delivers ±1% output voltage accuracy (0.800 V reference), supports I²C-based voltage margining and programmable power-on reset delay, and targets Power QUICC I/II and MPC8xxx microprocessor power systems.

For engineers reviewing the MC34702EK datasheet, MC34702EK pinout, MC34702EK application, or MC34702EK equivalent, key selection criteria include its integrated 3.0A buck + LDO controller architecture, 300 kHz default switching frequency with resistor-adjustable range (200–400 kHz), precise up/down power sequencing control via EN1/EN2 logic, thermal shutdown at 170°C typical, and Pb-free 32-pin SOICW packaging.

Technical Context

The MC34702EK implements a synchronous buck topology with integrated high-side and low-side N-channel MOSFETs (R_DS(ON) = 60 mΩ / 65 mΩ), driven by internal bootstrap circuitry supplying 7.75 V nominal at VBST. Its error amplifier features 80 dB open-loop gain and 35 MHz gain-bandwidth product for fast transient response.

Power sequencing is managed through dual enable inputs (EN1/EN2) selecting among four modes-including standard, inverted, or disabled sequencing-while the I²C interface (SCL/SDA) enables real-time voltage margining (±7.9%), watchdog timer configuration, and address selection via ADDR/CLKSEL pins.

Key Specifications

Pinout & Package

MC34702EK is housed in a 32-pin SOICW (Wide-body) package with exposed thermal pad. Pin functions are validated per Freescale Document Number MC34702 Rev 7.0 (2007), Figures 3 and Table 1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-output PMIC applications.

Compared with NCP5214MNR2G and TPS51220ARUKT, MC34702EK uniquely integrates both buck and LDO control with I²C configurability and four-mode sequencing-making it suitable for legacy Freescale processor platforms where discrete LDO management and firmware-independent reset timing are critical.

Availability

MC34702EK is available at Aetrix Electronics and suitable for Power QUICC-based telecom infrastructure, MPC8xxx industrial controllers, and automotive infotainment ECUs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MC34702EK 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 fabless semiconductor company specializing in embedded processing, analog, and power management solutions for automotive, industrial, and networking markets.

The MC34702EK belongs to Freescale's Power Management IC product line, designed specifically to simplify power delivery for Power QUICC and MPC8xxx microprocessor families with integrated sequencing, margining, and thermal protection.

FAQ

What is the default switching frequency of the MC34702EK and how is it adjusted?

The MC34702EK has a default switching frequency of 300 kHz when the FREQ pin is left open or tied to VDDI. Frequency adjustment is achieved by connecting an external resistor (RFREQ) between FREQ and GND: 7.0 kΩ yields ~400 kHz, 22 kΩ yields ~200 kHz, and values in between scale linearly per Figure 6 in the datasheet. This allows optimization of efficiency, EMI, and inductor size for each application.

Does the MC34702EK integrate power MOSFETs for both the buck and LDO sections?

The MC34702EK integrates N-channel high-side and low-side MOSFETs (R_DS(ON) = 60 mΩ / 65 mΩ) for the buck regulator. For the LDO section, it provides gate drive (LDRV) and current sensing (CS) but requires an external N-channel MOSFET (e.g., IRL2703) as the pass element. This architecture balances integration density with flexibility in LDO current capability and thermal management.

How does the MC34702EK implement power sequencing between core and I/O rails?

The MC34702EK uses dual enable inputs (EN1 and EN2) to select one of four sequencing modes per Table 5: disabled, standard (core first), inverted (I/O first), or no sequencing (both enabled simultaneously). Sequencing is enforced by internal power sequence control circuits monitoring VOUT and LDO pins, ensuring proper voltage ramp timing and hold-off intervals without external logic.

What is the role of the VBST pin on the MC34702EK and what voltage does it supply?

The VBST pin is the output of the internal boost regulator, providing a nominal 7.75 V (range 7.3–8.3 V) at up to 20 mA. This voltage powers the gate drivers for the integrated buck MOSFETs and the external LDO pass transistor driven by LDRV. Stable VBST is essential for maintaining sufficient gate overdrive under varying input conditions and load transients.

Can the MC34702EK be used in automotive applications, and what temperature range does it support?

Yes, the MC34702EK is rated for operation from –40°C to +85°C ambient temperature and includes thermal shutdown at 170°C typical, making it suitable for under-hood and cabin automotive infotainment ECUs. Its 2.8–6.0 V input range accommodates automotive battery transients, and Pb-free (EW suffix) packaging meets RoHS requirements for automotive electronics.