Overview
The MC33167THG is a high-performance fixed frequency power switching regulator produced by onsemi. This device is part of the MC34167 and MC33167 series, designed for dc-to-dc converter applications. It is optimized for step-down, voltage-inverting, and step-up configurations with a minimal number of external components. The regulator includes an internal temperature-compensated reference, a fixed frequency oscillator, a latching pulse width modulator, a high gain error amplifier, and a high current output switch. It also features protective mechanisms such as cycle-by-cycle current limiting, undervoltage lockout, and thermal shutdown, along with a low power standby mode.
Key Specifications
| Characteristic | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Oscillator Frequency (VCC = 7.5 V to 40 V) | fOSC | 65 | 72 | 81 | kHz |
| Voltage Feedback Input Threshold | VFB(th) | 4.95 | 5.05 | 5.20 | V |
| Power Supply Input Voltage | VCC | - | - | 40 | V |
| Switch Output Voltage Range | VO(switch) | -2.0 | - | + Vin | V |
| Operating Junction Temperature | TJ | - | - | 150 | °C |
| Operating Ambient Temperature (MC33167) | TA | -40 | - | 85 | °C |
| Maximum Peak Collector Current | - | - | - | 5.5 A | - |
| Power Supply Current (Standby) | ICC | - | - | 36 μA | - |
Key Features
- Fixed frequency oscillator at 72 kHz with on-chip timing components.
- High gain error amplifier and a high current output switch capable of switching up to 40 V.
- Protective features including cycle-by-cycle current limiting, undervoltage lockout, and thermal shutdown.
- Low power standby mode reducing power supply current to 36 μA.
- Internal temperature-compensated reference and latching pulse width modulator for single pulse metering.
- Soft-start capability using the error amplifier output with a 100 μA current source pull-up.
Applications
The MC33167THG is suitable for various applications including automotive, computer, industrial, and cost-sensitive consumer products. It can be used in step-down, voltage-inverting, and step-up converter configurations, making it versatile for different power management needs.
Q & A
- What is the typical oscillator frequency of the MC33167THG?
The typical oscillator frequency is 72 kHz. - What is the maximum peak collector current of the output transistor?
The maximum peak collector current is 5.5 A. - What are the protective features of the MC33167THG?
The protective features include cycle-by-cycle current limiting, undervoltage lockout, and thermal shutdown. - What is the operating ambient temperature range for the MC33167THG?
The operating ambient temperature range is -40°C to +85°C. - How does the low power standby mode function?
The low power standby mode reduces the power supply current to 36 μA by clamping the error amplifier output to less than 150 mV. - What is the purpose of the internal temperature-compensated reference?
The internal temperature-compensated reference ensures stable operation over a range of temperatures. - Can the MC33167THG be used in step-up converter applications?
Yes, the MC33167THG can be used cost-effectively in step-up converter applications. - What is the maximum power supply input voltage?
The maximum power supply input voltage is 40 V. - How does the soft-start feature work?
The soft-start feature uses the error amplifier output with a 100 μA current source pull-up to charge a capacitor, implementing a soft-start. - What type of rectifier is recommended for use with the MC33167THG?
A 1N5825 or equivalent Schottky barrier rectifier is recommended due to its high forward voltage drop and short turn-on delay time.
