Overview
The L4972A is a stepdown monolithic power switching regulator produced by STMicroelectronics. It delivers up to 2A of output current with an adjustable output voltage ranging from 5.1V to 40V. This device is realized using BCD mixed technology, which integrates isolated vertical DMOS power transistors along with mixed CMOS/Bipolar transistors. The L4972A is particularly suited for microprocessor-based systems due to its diagnostic and control functions, including reset and power fail signals, feed-forward line regulation, soft start, and thermal protection.
Key Specifications
| Parameter | Min. | Typ. | Max. | Unit |
|---|---|---|---|---|
| Input Voltage Range (pin 11) | 15 | - | 50 | V |
| Output Voltage | 5 | 5.1 | 5.2 | V |
| Output Current | - | - | 2 | A |
| Line Regulation | 12 | - | 30 | mV |
| Load Regulation | 7 | - | 20 | mV |
| Dropout Voltage between Pin 11 and 20 | 0.25 | - | - | V |
| Switching Frequency | - | - | 200 | KHz |
Key Features
- 2A output current
- Output voltage adjustable from 5.1V to 40V
- Internal feed-forward line regulation
- Internal current limiting and thermal shutdown
- Precise 5.1V ± 2% on-chip reference voltage
- Reset and power fail functions with delay and hysteresis
- Input/output sync pin for multiple device synchronization
- Under-voltage lockout with hysteresis
- PWM latch for single pulse per period
- Very high efficiency and fast switching times
- Soft start function to prevent output overcurrents at turn-on
Applications
The L4972A is particularly suitable for microprocessor-based systems due to its integrated diagnostic and control functions. It can be used in various applications such as:
- Power supplies for microprocessors and other digital circuits
- Multiple supply systems where synchronization between regulators is required
- Systems requiring high efficiency and fast switching times
- Applications needing precise voltage regulation and protection features like thermal shutdown and current limiting
Q & A
- What is the output current capability of the L4972A?
The L4972A can deliver up to 2A of output current.
- What is the adjustable output voltage range of the L4972A?
The output voltage can be adjusted from 5.1V to 40V.
- What technology is used in the L4972A?
The L4972A is realized using BCD mixed technology, integrating isolated vertical DMOS power transistors and mixed CMOS/Bipolar transistors.
- What are the key diagnostic and control functions of the L4972A?
The device includes reset and power fail functions, feed-forward line regulation, soft start, and thermal protection.
- How does the soft start function work in the L4972A?
The soft start function prevents output overcurrents at turn-on by clamping the error amplifier with an external capacitor and allowing it to rise linearly under the charge of an internal constant current source.
- What is the purpose of the PWM latch in the L4972A?
The PWM latch eliminates multiple pulsing within a period, even in noisy environments.
- How can multiple L4972A devices be synchronized?
Multiple devices can be synchronized by connecting their sync input pins together or via an external sync pulse.
- What is the thermal shutdown threshold of the L4972A?
The thermal shutdown occurs when the junction temperature reaches about 150°C, with a hysteresis to prevent unstable conditions.
- What are the available package options for the L4972A?
The device is available in PowerDIP20 (16+2+2) and SO20 packages.
- What is the typical switching frequency of the L4972A?
The switching frequency can be up to 200KHz.
