onsemi LA5735M-TE-L-E

Overview

LA5735M-TE-L-E from SANYO Semiconductor is a separately-excited step-down switching regulator IC with integrated 300 kHz time-base generator, current limiting (0.7 A threshold), and thermal shutdown (165 °C). It operates from 4.5 V to 32 V input, delivers up to 0.6 A output, and regulates via external resistor divider on the VOS pin (1.23 V reference). It is used in industrial DC-DC converters requiring adjustable output voltage and cycle-by-cycle overcurrent protection.

For engineers reviewing the LA5735M-TE-L-E datasheet, pinout, applications, or equivalent options, key selection considerations include its variable-output buck topology, built-in short-circuit protection at 15 kHz, saturation voltage of 1.15 V at 0.3 A, thermal hysteresis of 15 °C, and MFP8 (225 mil) surface-mount package compatibility.

Technical Context

The LA5735M-TE-L-E implements a fixed-frequency, externally synchronized buck controller architecture with internal oscillator (240–360 kHz), error amplifier referenced to 1.23 V, and comparator-driven PWM drive for an external N-channel MOSFET (via SWOUT pin). Its current limit triggers per-cycle at 0.7 A, and short-circuit mode reduces frequency to 15 kHz to limit power dissipation.

Thermal shutdown activates at 165 °C with 15 °C hysteresis, and the VOS pin serves as both feedback input and regulation setpoint-enabling output voltage adjustment from ~1.23 V upward using R1/R2 divider. The IC requires external diode, inductor, and input/output capacitors per application circuit.

Key Specifications

Pinout & Package

LA5735M-TE-L-E is housed in an 8-pin MFP8 (225 mil) surface-mount package with 1.27 mm pitch, glass-epoxy board mounting, and exposed thermal pad not electrically connected. Pin 1 = VIN, Pin 3 = SWOUT, Pin 4 = VOS, Pin 6 = GND; Pins 2, 5, 7, 8 are NC (no internal connection).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar separately-excited buck controller applications.

Compared with UCC3803D and NCP1200DR2G, LA5735M-TE-L-E offers integrated current limiting and adaptive short-circuit frequency reduction-reducing BOM count and improving fault resilience in buck-based industrial supplies without requiring external protection circuitry.

Availability

LA5735M-TE-L-E is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, point-of-load converters, and factory automation I/O modules requiring stable component supply and long-term lifecycle support.

Supply support for LA5735M-TE-L-E 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

SANYO Semiconductor was a Japanese semiconductor manufacturer specializing in analog and power ICs before its acquisition by ON Semiconductor in 2011; known for high-reliability industrial and automotive-grade products.

The LA5735M-TE-L-E belongs to SANYO's monolithic linear IC family targeting adjustable, externally switched DC-DC conversion in space-constrained industrial and automotive applications where integrated protection and thermal robustness are critical.

FAQ

What is the function of the VOS pin on the LA5735M-TE-L-E?

The VOS pin on the LA5735M-TE-L-E serves as the feedback input and internal 1.23 V reference node. It connects to a resistor divider between output and ground to set regulated output voltage using the formula VOUT = 1.23 × (1 + R2/R1). The LA5735M-TE-L-E monitors VOS voltage to adjust duty cycle and maintain regulation. Its specified operating range is –0.2 V to +7 V, and leakage current is ≤2 µA.

Does the LA5735M-TE-L-E support synchronous rectification?

No, the LA5735M-TE-L-E does not support synchronous rectification. It drives only the high-side external N-channel MOSFET via the SWOUT pin and requires an external Schottky barrier diode (SBD) for the low-side path. The datasheet explicitly specifies SBD use and warns against fast-recovery diodes due to reverse recovery stress. LA5735M-TE-L-E lacks a second gate driver or timing control for synchronous FETs.

What is the maximum allowable power dissipation for the LA5735M-TE-L-E at 85°C ambient?

At 85°C ambient, the LA5735M-TE-L-E's allowable power dissipation is approximately 0.52 W, derived from the Pd max vs. Ta curve on page A0588-3/7. The curve shows linear derating from 0.8 W at –30°C to 0 W at 140°C, yielding ~0.52 W at 85°C. This assumes mounting on the specified 114.3×76.1×1.6 mm glass-epoxy board; actual dissipation depends on PCB copper area and airflow.

Can the LA5735M-TE-L-E operate with an input voltage below 4.5 V?

No, the LA5735M-TE-L-E is not guaranteed to operate below 4.5 V. Its recommended operating input range is strictly 4.5 V to 32 V, and absolute maximum rating for VIN is 34 V. Below 4.5 V, internal bias circuits may fail to start or sustain oscillation, and reference voltage accuracy degrades. The LA5735M-TE-L-E has no undervoltage lockout (UVLO) specification below 4.5 V, so operation is outside validated design limits.

How does short-circuit protection work in the LA5735M-TE-L-E?

Short-circuit protection in the LA5735M-TE-L-E activates when the VOS pin voltage falls below 0.8 V, indicating severe output collapse. The IC then forces switching frequency down to 15 kHz-reducing average power delivered to the fault and limiting thermal stress. This mode remains active until VOS recovers above 0.8 V. The LA5735M-TE-L-E does not latch off; it resumes normal 300 kHz operation automatically upon fault clearance.