Texas Instruments UC37133N

Overview

UC37133N from Texas Instruments is a high-side smart power switch IC designed for industrial load control, featuring 300mA continuous output current, 8V–65V operating voltage range, and integrated short-circuit/overload protection. It drives inductive or resistive loads directly from the high side (load connected to GND), with 72V internal zener clamp, 6V regulated reference, and programmable fault timing via external CDEL capacitor.

For engineers reviewing the UC37133N datasheet, UC37133N pinout, UC37133N application, or UC37133N equivalent, this device is selected for robust high-side switching in automotive body electronics, PLC I/O modules, and industrial solenoid/valve drivers where VCC interruption resilience, precise current limiting, and LED status feedback are critical design requirements.

Technical Context

The UC37133N implements a composite PNP-NPN output stage optimized for high-side configuration only, with HS pin as emitter-connected output and CSH pin enabling current-sense threshold programming via resistor to VCC. Its fault logic uses a single CDEL capacitor to set both turn-on delay (9.5–13.5ms) and VCC interruption recovery time, with dual thresholds (VFAULT_H = 4.9V, VFAULT_L = 1.0V) governing charge/discharge-based protection sequencing.

It features fixed 30% input comparator hysteresis (1.025V), 3V threshold derived from internal 6V bandgap reference, and open-collector LED output that sinks 5–11mA when the driver is off. The 72V zener clamp between HS and LS/VCC enables safe inductive kickback suppression without external diodes in high-side configurations.

Key Specifications

Pinout & Package

UC37133N is housed in an 8-pin PDIP (Plastic Dual In-line Package) with 0.3-inch width, RoHS-compliant lead finish, and JEDEC MS-001AC package drawing. Pin 1 is bottom-left corner (notch-down orientation).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-side smart switch applications.

Compared with UC37133D, UC37133N offers identical functionality in through-hole form for legacy or prototyping use, while TPS27081A trades programmable fault timing and reference output for higher current capacity and thermal protection - making UC37133N optimal for precision-timed, diagnostics-enabled high-side control in space-constrained industrial environments.

Availability

UC37133N is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and building control systems requiring stable component supply, long-term obsolescence management, and traceable sourcing for safety-critical functions.

Supply support for UC37133N 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of experience in industrial and automotive-grade IC design.

The UC3713x family was developed specifically for ruggedized high-side and low-side power switching in harsh environments, emphasizing fault resilience, integrated protection, and simplified system-level design for load-driving applications.

FAQ

What is the maximum continuous output current supported by UC37133N?

The UC37133N supports 300mA continuous output current at 25°C ambient temperature, with derating to 250mA at 70°C junction temperature. This rating applies to high-side configurations with proper heatsinking and PCB copper area, and is validated under the specified test conditions in the SLUS340 datasheet with R_LOAD = 100Ω to GND.

Can UC37133N be used in low-side switching configurations?

No, UC37133N is designed exclusively for high-side switching. Its internal architecture connects the HS pin as the emitter output and requires the load between HS and GND. Attempting low-side use violates the pin functional definitions - for example, LS and CSL pins are absent in UC37133N, confirming its dedicated high-side role per the product selection tables and block diagrams.

How does the CDEL capacitor affect UC37133N behavior during power interruptions?

The CDEL capacitor on UC37133N programs both turn-on delay and VCC interruption recovery: a 10nF capacitor yields ~9.5ms turn-on delay and allows up to ~478µs VCC interruption without triggering full reset. If VCC drops below 7V for longer than t_D(OFF), UC37133N disables output and waits for CDEL to recharge to 4.9V before re-enabling - ensuring controlled restart after brownouts.

What is the purpose of the CSH pin on UC37133N?

The CSH pin on UC37133N is the high-side current sense input. Connecting a resistor (e.g., 0.5Ω) between VCC and CSH sets the overcurrent threshold - when voltage drop across RCSH exceeds 150mV, UC37133N initiates short-circuit protection. This pin is essential for configuring load-current limits and is unused in low-side variants like UC37131.

Does UC37133N include built-in protection against inductive kickback?

Yes, UC37133N integrates a 72V zener diode between HS and VCC/LS, enabling safe clamping of inductive flyback energy during turn-off. This eliminates the need for external flyback diodes in high-side configurations - verified by the "Output Short Circuit" and "Voltage Clamp" specifications in the Electrical Characteristics table, where LS–HS clamp is rated 67–77V.