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TL494CN
The TL494CN is a voltage-mode pulse-width modulation (PWM) controller integrated circuit manufactured by Texas Instruments, packaged in a 16-pin plastic dual in-line package (PDIP-16) through-hole housing. The device integrates two error amplifiers, an on-chip adjustable oscillator, a dead-time control (DTC) comparator, a pulse-steering control flip-flop, a 5 V ±5% precision reference regulator, and output-control circuits on a single die. Operating supply voltage ranges from 7 V to 40 V, and the oscillator supports switching frequencies up to 300 kHz. Each output channel provides 200 mA sink or source current. The device supports both single-ended and push-pull output modes, selectable via the output control pin. Internal logic inhibits double-pulse output in push-pull mode to prevent transformer saturation. The TL494CN is characterized for operation from 0°C to +70°C (commercial grade) and is supplied in tube packaging at 25 units per tube. It is RoHS compliant and lead-free.
The TL494CN integrates all core functions required for switching power supply design on a single chip, including the oscillator, error amplifiers, reference regulator, dead-time comparator, and output drivers. This integration reduces the peripheral component count and board area compared with discrete PWM implementations.
The output control pin (pin 13) configures the device for either single-ended or push-pull operation. Single-ended mode suits flyback and forward converter topologies, while push-pull mode supports half-bridge and push-pull converters. Each channel delivers a maximum duty cycle of approximately 45% in push-pull mode.
The dead-time control comparator incorporates a fixed offset that provides approximately 5% dead time, preventing simultaneous conduction of upper and lower power switches. Internal logic further prohibits double-pulse output in push-pull mode, reducing the risk of transformer saturation and power device breakdown.
The two error amplifiers support a common-mode input voltage range from -0.3 V to VCC - 2 V. One amplifier typically handles output voltage stabilization, while the second can be configured for over-current protection, constant-current charging, or remote voltage monitoring. This dual-amplifier architecture satisfies the composite control requirements of battery chargers and adjustable laboratory power supplies.
The standard PDIP-16 through-hole package supports manual soldering and socket-based prototyping, making the device suitable for both design verification and volume manufacturing. The package is widely available through authorized component distributors.
Model | TL494CN |
|---|---|
Manufacturer | Texas Instruments |
Function | Voltage-Mode PWM Controller IC |
Package | PDIP-16 (DIP16) Through Hole |
Supply Voltage Range | 7 V - 40 V |
Oscillator Frequency Range | Up to 300 kHz |
Internal Reference Voltage | 5 V (±5% tolerance) |
Output Driver Current | 200mA sink/source per channel |
Output Mode | Single-Ended / Push-Pull Selectable |
Built-in Module | Dual Error Amplifiers, Dead Time Comparator |
Operating Temperature | 0 ℃ - +70 ℃ |
Max Duty Cycle (Push-Pull) | 45% per channel |
Packaging | Tube packing |
Compliance | RoHS Lead-free |
The TL494CN serves as the control core in AC-DC and DC-DC switching power supplies for industrial equipment, supporting flyback, forward, push-pull, and half-bridge topologies.
Used in low-to-medium power inverter circuits where voltage-mode PWM control and push-pull output drive are required for transformer-coupled power stages.
The dual error amplifiers enable combined constant-voltage and constant-current charging profiles, suitable for lead-acid and lithium-ion battery charger designs.
The combination of adjustable oscillator frequency, dual control loops, and through-hole packaging makes the device suitable for bench-top adjustable power supply projects and educational prototypes.
The "C" suffix indicates commercial-grade temperature range (0°C to +70°C), while the "I" suffix indicates industrial-grade range (-40°C to +85°C). The "N" indicates PDIP-16 packaging. Both variants share the same electrical characteristics within their respective temperature ranges.
The oscillator frequency is determined by an external resistor RT connected to pin 6 and a capacitor CT connected to pin 5. The frequency is approximately f = 1.1 / (RT × CT), where RT is in ohms and CT is in farads.
Yes. The second error amplifier can be configured as a current-sense control loop, enabling constant-current charging alongside the primary voltage-regulation loop.
In single-ended output mode, the maximum duty cycle approaches 95%, limited only by the fixed dead-time offset. In push-pull mode, each output channel is limited to approximately 45% maximum duty cycle to prevent overlap.
The TL494CN specifically refers to the PDIP-16 through-hole variant. Surface-mount equivalents include the TL494CD (SOIC-16) and TL494CPW (TSSOP-16), which share the same die and electrical specifications.
