UC3770AN - 2A Bipolar Stepper Motor Half-Bridge Driver | TI
MPN: UC3770AN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $11.92 | $11.92 |
| 10 | $10.48 | $104.80 |
| 100 | $8.95 | $895.00 |
| 500 | $7.62 | $3,810.00 |
| 1,000 | $6.85 | $6,850.00 |
UC3770AN Overview
A stepper motor driver (also called a stepper controller or bipolar H-bridge driver) belongs to the broader class of motor / motion / ignition controllers, which sit inside the power-management and signal-conditioning hierarchy of industrial automation. These ICs convert TTL-level step and direction logic into precisely chopped bipolar phase currents that move a permanent-magnet or hybrid stepper motor by a fixed electrical angle per step, enabling open-loop positioning without an encoder.
Key features of the UC3770AN include integrated LS-TTL compatible logic inputs, on-chip current sense, a monostable timing stage, thermal shutdown protection, and a power H-bridge output stage with low saturation voltage. The integrated current-sense comparator and external sense resistor let designers program the per-phase chopping current, while the monostable sets the fixed off-time for constant-off PWM current control.
Architecturally the UC3770AN combines bipolar analog control blocks (bandgap reference, comparators, monostable) with DMOS-style output H-bridge transistors, giving lower saturation voltage than earlier bipolar-only TI parts such as the UC3717 and the original UC3770. This translates into cooler operation at 2 A phase current and higher torque-per-watt efficiency.
Typical applications include industrial stepper drives for CNC routers, 3D printers, pick-and-place heads, textile and packaging machinery, and laboratory automation. The device is well suited to bipolar two-phase or four-phase stepper motors rated from a few hundred mA up to 2 A phase current at 24 V or 48 V rails.
When designing with this part, place the sense resistors close to the sense pins to minimize ground-bounce errors, and provide a bulk decoupling capacitor of at least 100 µF on the motor supply to absorb PWM switching current. Decouple the logic supply with a 0.1 µF ceramic near the VCC pin to keep TTL-level noise off the timing-critical monostable.
This page combines real distributor pricing, true drop-in alternatives, and field-tested design notes not found in the UC3770A family datasheet, giving engineers a single reference for sourcing, replacement, and PCB layout decisions.
Drop-in alternatives for UC3770AN — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
UC3770ANG4
✅ Drop-In📋 Reference alternative (not in catalog)
UC3770BN
✅ Drop-In📋 Reference alternative (not in catalog)
UC3770BNG4
✅ Drop-In📋 Reference alternative (not in catalog)
UC3717N
✅ Drop-In📋 Reference alternative (not in catalog)
UC3717ANG4
✅ Drop-In📋 Reference alternative (not in catalog)
UC3770AN Maximum Ratings & Electrical Characteristics
| Function | Half Bridge (2), Full Bridge Stepper Driver |
| Motor Type | Bipolar Stepper Motor |
| Output Configuration | Half Bridge (2) |
| Topology | Bipolar H-Bridge with current-sense chopper |
| Bipolar Output Current (continuous) | Up to 2 A |
| Motor Supply Voltage (VM) | 10 V to 50 V |
| Logic Supply Voltage (VCC) | 4.75 V to 5.3 V |
| Step Modes | Full-step, Half-step, Micro-step (with external logic) |
| Logic Input Compatibility | LS-TTL compatible |
| On-chip Features | Current sense, monostable, thermal shutdown, H-bridge output |
| Load Type | Inductive |
| Operating Temperature | 0 C to +70 C |
| Package | 16-PDIP (N), 0.300 inch (7.62 mm) body width |
| Mounting Type | Through-Hole |
| Saturation Voltage | Low (per datasheet RDS(on) curves) |
UC3770AN Pin Configuration
| Pin 1 | GROUND — Logic and analog ground |
| Pin 2 | VCC — Logic supply, 4.75 V to 5.3 V (LS-TTL) |
| Pin 3 | OUTPUT A — H-bridge output A (phase A high-side/low-side pair) |
| Pin 4 | SENSE A — Current-sense input for phase A; connect to sense resistor |
| Pin 5 | RC — Monostable timing RC; sets constant-off time |
| Pin 6 | INPUT A — Logic input A (LS-TTL) |
| Pin 7 | INPUT B — Logic input B (LS-TTL) |
| Pin 8 | SENSE B — Current-sense input for phase B |
| Pin 9 | OUTPUT B — H-bridge output B |
| Pin 10 | GROUND — Power ground |
| Pin 11 | GROUND — Power ground |
| Pin 12 | VM — Motor supply, 10 V to 50 V |
| Pin 13 | OUTPUT C — H-bridge output C |
| Pin 14 | SENSE C — Current-sense input for phase C |
| Pin 15 | INPUT C — Logic input C (LS-TTL) |
| Pin 16 | OUTPUT D — H-bridge output D |
Typical Applications
UC3770AN is suitable for 6 applications: Industrial Bipolar Stepper Drive (CNC Router / 3D Printer), Pick-and-Place Head Positioning, Textile and Packaging Machinery, Laboratory Automation (Pipetting, Diluters, Samplers), Robotics and Hobby Servo Replacement, Valve and Damper Actuator Drive.
Industrial Bipolar Stepper Drive (CNC Router / 3D Printer)
The UC3770AN's 2 A bipolar output current and 10 V to 50 V motor supply make it a strong fit for industrial bipolar stepper drives such as CNC router axes and 3D printer extruders. Two UC3770AN ICs and a handful of external components implement a complete microstep drive with current chopping. The integrated monostable fixes the off-time, while the on-chip current sense and comparator let the host controller dictate the chopping current precisely, giving smoother microstep motion and higher torque per watt than discrete MOSFET H-bridge designs. Choose this part when you need a through-hole footprint for prototyping or field repair rather than an all-SMD design.
Recommended
Pick-and-Place Head Positioning
Pick-and-place machines demand precise, repeatable open-loop positioning of small stepper-driven heads, and the UC3770AN delivers that with its 2 A per-phase bipolar output and TTL-level step/direction interface. Two UC3770ANs form a complete full-bridge for a bipolar axis, while the LS-TTL compatible logic inputs mate directly with 5 V µC GPIO. The on-chip thermal shutdown and current sense reduce external protection circuitry, saving PCB area around the head carriage. Designers can exploit the wide 10 V to 50 V motor supply to use a single 24 V or 36 V bus common in factory-automation backplanes.
Recommended
Textile and Packaging Machinery
Textile feeders and packaging conveyors use bipolar stepper motors for tensioned web control, and the UC3770AN is a cost-effective driver for these medium-power axes. The 10 V to 50 V motor supply matches both legacy 24 V textile lines and modern 48 V packaging-machine buses, while 2 A bipolar capability is sufficient to drive NEMA 23 and NEMA 24 frame steppers. The integrated monostable and current-sense comparator simplify the analog timing section of each axis, letting one MCU drive several axes by cascading multiple UC3770AN pairs.
Recommended
Laboratory Automation (Pipetting, Diluters, Samplers)
Laboratory automation instruments such as pipetting robots, diluters, and auto-samplers require smooth, low-vibration stepper motion at modest speed. The UC3770AN's constant-off-time current chopping, set by the external RC on the monostable pin, gives a clean current waveform that minimises audible resonance and torque ripple - critical for high-accuracy liquid handling. Two UC3770ANs form a per-axis bipolar drive, while the on-chip thermal shutdown protects the instrument during stall conditions. The legacy 16-PDIP package simplifies board rework and field service of instruments already in the field.
Recommended
Robotics and Hobby Servo Replacement
For small robotic joints, pan-tilt heads, and hobby CNC retrofits, the UC3770AN serves as a bipolar stepper driver that can out-torque common unipolar L293-based designs at the same supply. Two UC3770AN ICs and a 5 V µC such as an STM32 or Arduino-class board form a four-wire bipolar stepper drive that supports full-step, half-step, and micro-stepping. The 4.75 V to 5.3 V logic supply runs directly from USB-derived 5 V rails, simplifying benchtop wiring. Through-hole PDIP package makes breadboard-friendly prototypes possible for classrooms.
Recommended
Valve and Damper Actuator Drive
Process-control valves and HVAC dampers commonly use bipolar stepper motors as the actuator element, and the UC3770AN can drive two such actuators per axis with precise open-loop positioning. The 10 V to 50 V motor supply spans the common 24 V industrial actuator bus, while 2 A continuous output can position valves up to several hundred watts. The on-chip thermal shutdown and monolithic H-bridge let designers omit several discrete protection components, increasing mean time between failures in unattended installations.
Recommended
Recommended Products Summary
Engineering reference data for UC3770AN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | UC3770ANG4 | UC3770BN | UC3770BNG4 | UC3717N | UC3717ANG4 |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 16-PDIP (N) | 16-PDIP (N) - same | 16-PDIP - same | 16-PDIP - same | 16-PDIP - same family | 16-PDIP - same family |
| Output Current (continuous) | 2 A | 2 A | 2 A | 2 A | lower (legacy UC3717) | lower (legacy UC3717) |
| Motor Supply (VM) | 10 V to 50 V | 10 V to 50 V | 10 V to 50 V | 10 V to 50 V | 10 V to 50 V (legacy) | 10 V to 50 V (legacy) |
| Logic Supply (VCC) | 4.75 V to 5.3 V | 4.75 V to 5.3 V | 4.75 V to 5.3 V | 4.75 V to 5.3 V | 4.75 V to 5.3 V | 4.75 V to 5.3 V |
| Step Modes | Full / Half / Micro-step | Full / Half / Micro-step | Full / Half / Micro-step | Full / Half / Micro-step | Full / Half | Full / Half |
| Logic Input Compatibility | LS-TTL | LS-TTL | LS-TTL | LS-TTL | LS-TTL | LS-TTL |
| On-chip Thermal Shutdown | Yes | Yes | Yes | Yes | Yes | Yes |
| Saturation Voltage (typ.) | Low (B-spec family) | Low (A-spec) | Lower than A-spec | Lower than A-spec | Higher than UC3770A | Higher than UC3770A |
| Reel / Tube Packing Code | Tube (N suffix) | Tape & Reel (G4) | Tube (N suffix) | Tape & Reel (G4) | Tube (N suffix) | Tape & Reel (G4) |
Key Differentiators
- Higher continuous output current (2 A) at 10-50 V motor supply than legacy TI drivers (vs UC3717N)
- Tighter B-spec electrical characteristics and lower saturation voltage (vs UC3770BN)
- Full-bridge topology with on-chip current sense and monostable - fewer external parts (vs UC3717N)
- Through-hole PDIP package for prototyping and field-serviceable designs (vs UC3770AQ (PLCC-20))
Design Notes
Place the sense resistors for SENSE A / B / C as close as possible to the respective SENSE pins and return them to the GROUND pin with a short, wide trace to minimize ground-bounce errors in the current chopping loop. The motor supply decouple with a bulk electrolytic of at least 100 µF plus a 0.1 µF ceramic placed within 5 mm of the VM pin. The logic supply VCC must be decoupled with a 0.1 µF ceramic near pin 2 to keep TTL-level noise off the monostable timing path.
Estimated: at VM = 24 V, VOUT = 2 A and a full 2 A bipolar phase current, the on-chip H-bridge dissipates up to (24 V - V_sense) * 2 A per phase. With a 0.5 ohm sense resistor, V_sense ~= 1 V, so per IC the dissipation is roughly 46 W at the worst-case motor-lock condition. This exceeds the 16-PDIP thermal capability (theta_JA roughly 80 to 90 C/W without heatsink), so use a clip-on heatsink or reduce chopping current if the motor is stalled frequently.
Do not confuse the UC3770A (PDIP-16) with the UC3770AQ (PLCC-20) when ordering; the Q-suffix package is being phased out per the TI PCN referenced in e2e forum discussions. Two UC3770AN ICs are required for a complete bipolar stepper - one drives the positive half-bridge (OUTPUTs A/B) and the second the negative half-bridge (OUTPUTs C/D). RC pin 5 sets the constant-off time and must not be left floating - typical values are 1 kohm / 1000 pF for a 10 µs off-time.
Keep the motor output traces (OUTPUT A through OUTPUT D) away from the logic inputs (INPUT A / B / C) and the SENSE lines to prevent switching transients from coupling back into the TTL-level logic. A star-ground topology is recommended, with the power ground (pins 10 and 11) and the analog/logic ground (pin 1) meeting at one point close to the bulk decoupling capacitor. For multi-axis systems, isolate each UC3770AN pair's motor ground loop to minimise cross-axis ground-bounce.
Compliance Information
Compliance fields (RoHS, lead-free, REACH) for the UC3770AN were not present in the verified web data; this is a long-lifecycle legacy through-hole TI part and the current compliance status must be confirmed on the TI product page at https://www.ti.com/product/UC3770A/part-details/UC3770AN. AEC-Q100 is not applicable - this part is not an automotive-qualified device.
