Overview
The TL7660CDR, manufactured by Texas Instruments, is a CMOS switched-capacitor voltage converter designed to perform supply-voltage conversions from positive to negative. This device is part of the TL7660 series and is specifically packaged in an 8-SOIC format, operating over a temperature range of –40°C to 85°C. It requires only two noncritical external capacitors for its charge pump and charge reservoir functions, making it a simple and efficient solution for generating negative voltage supplies.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VCC Supply Voltage | 1.5 | - | 10 | V |
| Operating Temperature Range | –40 | - | 85 | °C |
| Oscillator Frequency (VCC = 5 V) | - | 10 kHz | - | kHz |
| Supply Current (VCC = 3 V, LV = GND) | - | 60 | 100 | µA |
| Output Source Resistance (VCC = 2 V, IO = 3 mA) | - | 125 | 200 | Ω |
| Power Efficiency (RL = 5 kΩ) | 95 | - | 98 | % |
| Voltage Conversion Efficiency (RL = ∞) | 99 | - | 99.9 | % |
Key Features
- Converts positive input voltage to a complementary negative output voltage without the need for an external diode.
- Operates over a wide supply voltage range from 1.5 V to 10 V.
- Can be configured as a voltage doubler to generate output voltages up to 18.6 V with a 10-V input.
- High efficiency with typical power efficiency of 98% and voltage conversion efficiency of 99.9%.
- Requires only two external capacitors (10 µF polarized electrolytic types) for operation.
- Automatic latch-up protection through a logic network that senses the output voltage and adjusts substrate bias accordingly.
- Oscillator frequency can be adjusted by adding an external capacitor to the OSC terminal or by overdriving OSC with an external clock.
Applications
- On-board negative supplies for various electronic systems.
- Data-acquisition systems requiring negative voltage supplies.
- Portable electronics where space and efficiency are critical.
- Voltage doubling applications to generate higher output voltages.
- Cascading multiple TL7660 devices to achieve higher negative voltage multiplication.
Q & A
- What is the primary function of the TL7660CDR?
The TL7660CDR is a CMOS switched-capacitor voltage converter that converts a positive input voltage to a complementary negative output voltage.
- What is the operating temperature range of the TL7660CDR?
The TL7660CDR operates over a temperature range of –40°C to 85°C.
- How many external capacitors are required for the TL7660CDR to operate?
The TL7660CDR requires only two external capacitors (typically 10 µF polarized electrolytic types) for its charge pump and charge reservoir functions.
- Can the TL7660CDR be used as a voltage doubler?
- How is the oscillator frequency of the TL7660CDR adjusted?
The oscillator frequency can be adjusted by adding an external capacitor to the OSC terminal or by overdriving OSC with an external clock.
- What is the typical power efficiency of the TL7660CDR?
The typical power efficiency of the TL7660CDR is 98%.
- How does the TL7660CDR protect against latch-up?
The TL7660CDR has a logic network that senses the output voltage and adjusts the substrate bias of the MOS switches to prevent latch-up.
- Can multiple TL7660CDR devices be cascaded?
- What are the typical applications of the TL7660CDR?
The TL7660CDR is typically used in on-board negative supplies, data-acquisition systems, portable electronics, and voltage doubling applications.
- How is the output ripple voltage affected in the TL7660CDR?
The output ripple voltage is affected by the ESR (Equivalent Series Resistance) of the capacitors and the load current. Using low ESR capacitors can improve the output ripple performance.
