Texas Instruments UC3770ANG4

Overview

UC3770ANG4 from Texas Instruments is a high-performance bipolar stepper motor full-bridge driver IC with LS-TTL-compatible logic inputs, integrated current sense, monostable timing, thermal shutdown, and H-bridge output stage. It delivers up to 2A bipolar output current, supports motor supply voltages from 10V to 50V, and enables full-step, half-step, and micro-step operation in embedded motion control systems.

For engineers reviewing the UC3770ANG4 datasheet, UC3770ANG4 pinout, UC3770ANG4 application, or UC3770ANG4 equivalent, key selection criteria include its 16-pin PDIP package, 0°C to 70°C ambient operating range, current sense threshold compatibility with UC3717 for drop-in replacement, and requirement for external high-side clamp diodes.

Technical Context

The UC3770ANG4 implements a dual-source/sink H-bridge topology with independent current regulation via an internal comparator and external RC timing network (RT/CT). Its current sense thresholds-400–430 mV (I₀=L, I₁=L), 240–265 mV (I₀=H, I₁=L), and 70–90 mV (I₀=L, I₁=H)-enable precise step-mode current scaling for full/half/micro-stepping without microcontroller PWM.

Thermal protection triggers at +170°C junction temperature with soft intervention, and logic-level inputs (7, 8, 9) accept standard TTL thresholds (0.8 V low, 2.0 V high). Unlike UC3717, it requires external high-side clamp diodes due to absence of internal clamping circuitry.

Key Specifications

Pinout & Package

UC3770ANG4 is housed in a 16-pin plastic dual in-line package (PDIP-N), with 0.3-inch body width and through-hole mounting. Pin 1 is located at the left end of the top row when viewed from top with notch or dot oriented upward.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar stepper motor driver applications.

Compared with TB6600HG and DRV8811PWPR, UC3770ANG4 offers unique hardware-programmable current thresholds for deterministic microstepping without MCU intervention, while maintaining compatibility with legacy UC3717 layouts-though it mandates external high-side clamp diodes not needed by the newer alternatives.

Availability

UC3770ANG4 is available at Aetrix Electronics and suitable for industrial CNC positioning, medical infusion pumps, automated laboratory equipment, and printed circuit board assembly tools requiring stable component supply across extended production lifecycles.

Supply support for UC3770ANG4 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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management technologies with over 90 years of innovation history.

The UC3770 series belongs to TI's legacy motor driver portfolio designed specifically for cost-sensitive, high-reliability stepper motor control in industrial and instrumentation applications where analog current regulation and thermal robustness are critical.

FAQ

What is the maximum motor supply voltage supported by UC3770ANG4?

The UC3770ANG4 supports a motor supply voltage (VM) range of 10 V to 50 V, with absolute maximum rating at 50 V. Operation above 45 V is not recommended per electrical characteristics testing conditions, and sustained use near the 50 V limit requires careful attention to power dissipation and thermal design. The UC3770ANG4 must be used with external high-side clamp diodes to handle inductive kickback safely at these voltages.

Does UC3770ANG4 require external high-side clamp diodes?

Yes, UC3770ANG4 requires external high-side clamp diodes - unlike earlier UC3717 or newer integrated drivers. This is explicitly stated in the datasheet: "Unlike the UC3717, the UC3770A and the UC3770B require external high-side clamp diodes." These diodes protect the H-bridge outputs during current decay and must be rated for the full motor supply voltage and peak current. Failure to install them risks output transistor failure.

How does UC3770ANG4 implement micro-stepping without a microcontroller?

UC3770ANG4 achieves micro-stepping through hardware-based current level selection using two logic inputs (I₀ and I₁) that configure three distinct current sense thresholds (70–90 mV, 240–265 mV, 400–430 mV). Combined with external RC timing on Pin 11, this enables open-loop chopper regulation at precise fractions of full-scale current - supporting full-step, half-step, and micro-step waveforms without PWM or firmware control. The UC3770ANG4 thus reduces MCU resource load in simple motion systems.

What is the operating temperature range for UC3770ANG4?

The UC3770ANG4 is specified for operation from 0°C to +70°C ambient temperature. Its thermal shutdown activates at +170°C junction temperature, providing safety margin under overload. For reliable long-term operation, PCB layout must ensure adequate copper area and airflow, especially when delivering 2 A continuously. Derating is recommended above +50°C ambient to maintain junction temperature below +150°C maximum rating.

Is UC3770ANG4 pin-compatible with UC3717?

UC3770ANG4 is not pin-compatible with UC3717 - though its current sense thresholds match UC3717 to enable functional drop-in replacement *in applications where external high-side clamp diodes are acceptable*. Pin assignments differ significantly: UC3717 uses a 20-pin DIP, while UC3770ANG4 uses a 16-pin PDIP with different signal mapping (e.g., dedicated Emitters, Phase, VR pins). Direct PCB substitution requires layout revision.