Microchip TC7660EOA CMOS Voltage Converter: Datasheet, Pinout, and Application Circuit Guide

The Microchip TC7660EOA is a monolithic, CMOS-based voltage converter IC that has become a staple in electronic design for its simplicity and effectiveness in generating a negative output voltage from a positive input. This device is widely used to provide a negative supply rail in systems where only a single positive voltage is available, making it indispensable for powering operational amplifiers, sensors, and other analog circuitry.

This guide provides a detailed overview of its datasheet specifications, pin configuration, and a practical application circuit to help you integrate this component into your designs seamlessly.

Datasheet Overview and Key Specifications

The TC7660EOA operates over a wide input voltage range, typically from 1.5V to 12V, and can deliver output currents of up to 20mA with a typical power conversion efficiency of 99.9%. Its low operating current (typically 80µA) makes it highly suitable for battery-powered and portable applications.

Key electrical characteristics include:

Output Voltage: -VIN (under minimal load conditions)

Output Resistance: Typically 55Ω at 25°C

Oscillator Frequency: Typically 10kHz (set by internal oscillator, can be overridden with an external clock)

Operating Temperature Range: -40°C to +85°C

The device is housed in an 8-pin SOIC package (OA suffix), offering a compact footprint for space-constrained PCB designs.

Pinout Configuration

Understanding the pinout is crucial for correct circuit implementation. The TC7660EOA in the 8-pin SOIC package has the following pin functions:

1. CAP+ (Pin 1): Positive terminal of the external charge pump capacitor.

2. GND (Pin 2): Ground (0V) reference.

3. CAP- (Pin 3): Negative terminal of the external charge pump capacitor.

4. VOUT (Pin 4): Negative output voltage (-VIN).

5. LV (Pin 5): Low-Voltage Control. Connecting this pin to GND allows operation with an input voltage below 3.5V. Leave unconnected for VIN > 3.5V.

6. OSC (Pin 6): Oscillator Control. Leaving this pin open uses the internal oscillator. Connecting a capacitor to GND lowers the frequency; an external clock can be applied here to override the internal oscillator.

7. V+ (Pin 7): Positive input supply voltage.

8. NC (Pin 8): No Internal Connection. This pin can be left floating or tied to GND.

Standard Application Circuit Guide

The most common application for the TC7660EOA is the voltage inverter configuration. The circuit is remarkably simple, requiring only two external components.

Components Required:

IC1: TC7660EOA

C1: Charge Pump Capacitor, 10µF (tantalum or aluminum electrolytic)

C2: Reservoir Capacitor, 10µF (tantalum or aluminum electrolytic)

Circuit Connection:

1. Connect Pin 7 (V+) to the positive supply rail (e.g., +5V).

2. Connect Pin 2 (GND) to the system ground.

3. Connect the positive lead of capacitor C1 to Pin 1 (CAP+).

4. Connect the negative lead of capacitor C1 to Pin 3 (CAP-).

5. Connect the positive lead of capacitor C2 to Pin 2 (GND).

6. Connect the negative lead of capacitor C2 to Pin 4 (VOUT). This will provide the negative output voltage.

7. For standard operation with VIN > 3.5V, leave Pin 5 (LV) unconnected.

8. To use the internal oscillator, leave Pin 6 (OSC) unconnected.

In this configuration, with a +5V input, the output at VOUT will be approximately -5V, capable of sourcing up to 20mA of current.

ICGOODFIND: The Microchip TC7660EOA stands out as an exceptionally efficient and easy-to-use solution for on-board negative voltage generation. Its minimal external component count, low power consumption, and flexibility offered by the OSC and LV pins make it a superior choice for a vast range of applications, from industrial instrumentation to consumer portable devices. Its robustness and reliability, backed by Microchip's quality, ensure stable performance in your critical circuits.

Keywords: Voltage Converter, Charge Pump, Negative Voltage Generator, CMOS, Application Circuit