Overview
The TL594CDRG4, produced by Texas Instruments, is a pulse-width-modulation (PWM) control circuit designed primarily for power-supply control. This device integrates all the necessary functions for constructing a PWM control circuit on a single chip, offering flexibility to tailor the power-supply control circuitry to specific applications. The TL594 includes two error amplifiers, an on-chip adjustable oscillator, a dead-time control (DTC) comparator, a pulse-steering control flip-flop, a 5-V regulator with 1% precision, an undervoltage lockout control circuit, and output control circuitry. This comprehensive integration reduces the amount of additional circuitry required in the total design, making it a versatile component for various power supply applications.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VCC Operating Voltage | 7 | - | 40 | V |
| Oscillator Frequency | 400 | - | 100k | Hz |
| Output Current (each transistor) | - | - | 200 | mA |
| Output Voltage Rise Time (common-emitter) | 100 | 200 | - | ns |
| Output Voltage Fall Time (common-emitter) | 30 | 100 | - | ns |
| Undervoltage Lockout Threshold | 6 | - | - | V |
| Operating Temperature Range | 0°C to 70°C (TL594C) | - | -40°C to 85°C (TL594I) | °C |
| Package Types | SOIC (16), PDIP (16), SO (16), TSSOP (16) | - | - | - |
Key Features
- Output Control: Selects single-ended or push-pull operation.
- Internal Regulator: Provides a stable 5-V reference supply trimmed to 1%.
- Undervoltage Lockout: Locks the outputs off until the internal circuitry is operational.
- Adjustable Oscillator: Can be bypassed or used to drive common circuitry in synchronous multiple-rail power supplies.
- Error Amplifiers: Have a common-mode voltage range of –0.3 V to VCC – 2 V.
- Dead-Time Control: Provides approximately 5% dead time.
- Pulse-Steering Flip-Flop: Alternately directs the modulated pulse to each of the two output transistors.
- Output Transistors: Uncommitted, capable of sinking or sourcing up to 200 mA, with common-emitter or emitter-follower output capability.
Applications
- Power Supplies: AC/DC, isolated, with or without Power Factor Correction (PFC), and those below or above 90 W.
- Server Power Supplies: Telecom and server AC/DC supplies.
- Solar Power Inverters and Micro-Inverters: Suitable for solar power conversion systems.
- White Goods: Appliances such as refrigerators, washing machines, etc.
Q & A
- What is the primary function of the TL594?
The TL594 is a pulse-width-modulation (PWM) control circuit designed primarily for power-supply control.
- What are the key components of the TL594?
The TL594 includes two error amplifiers, an on-chip adjustable oscillator, a dead-time control (DTC) comparator, a pulse-steering control flip-flop, a 5-V regulator, an undervoltage lockout control circuit, and output control circuitry.
- How does the output control function work?
The output control function allows selection between single-ended or push-pull operation by setting the OUTPUT CTRL pin to ground or VREF, respectively.
- What is the purpose of the undervoltage lockout?
The undervoltage lockout locks the outputs off until the internal circuitry is operational, ensuring that the device does not operate below a minimum VCC voltage of 6 V.
- How is the oscillator frequency programmed?
The oscillator frequency is programmed by selecting the timing components RT and CT, which determine the charging current and period of the sawtooth waveform.
- What is the output current capability of the TL594?
Each output transistor can sink or source up to 200 mA.
- What are the operating temperature ranges for the TL594?
The TL594C is characterized for operation from 0°C to 70°C, while the TL594I is characterized for operation from –40°C to 85°C.
- What types of packages are available for the TL594?
The TL594 is available in SOIC (16), PDIP (16), SO (16), and TSSOP (16) packages.
- Can the TL594 be used in synchronous multiple-rail power supplies?
Yes, the on-chip oscillator can be used to drive common circuitry in synchronous multiple-rail power supplies.
- What is the precision of the internal 5-V reference regulator?
The internal 5-V reference regulator has a precision of 1% and maintains a stability of less than 25-mV variation over an input voltage range of 7 V to 40 V.
