CMOS Voltage Converters # Technical Documentation: 7660CBA Voltage Converter
Manufacturer : INTERSIL
Component Type : Switched-Capacitor Voltage Converter/Inverter
## 1. Application Scenarios
### Typical Use Cases
The 7660CBA is primarily employed in applications requiring voltage inversion or doubling from low-voltage power sources. Common implementations include:
- Voltage Inversion : Converting positive DC voltages to negative equivalents (e.g., +5V to -5V)
- Voltage Doubling : Generating higher voltages from single power supplies (e.g., +5V to +10V)
- Battery-Powered Systems : Creating dual-rail supplies from single batteries in portable equipment
- Signal Conditioning : Providing negative bias voltages for operational amplifier circuits
### Industry Applications
- Consumer Electronics : Portable audio equipment, handheld instruments
- Industrial Control : Sensor interfaces, data acquisition systems
- Telecommunications : Line interface circuits, modem power supplies
- Medical Devices : Portable monitoring equipment requiring dual supplies
- Automotive Electronics : Sensor systems, infotainment peripherals
### Practical Advantages and Limitations
Advantages:
- High Efficiency (up to 98% in voltage doubling mode)
- Minimal External Components (typically only 2 capacitors required)
- Wide Operating Range (1.5V to 10V supply voltage)
- Low Power Consumption (typically 80µA quiescent current)
- Temperature Stability (-40°C to +85°C operating range)
Limitations:
- Limited Output Current (typically 20-40mA maximum)
- Output Impedance increases with lower supply voltages
- Clock Feedthrough can cause noise in sensitive analog circuits
- Start-up Time considerations for time-critical applications
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pump Capacitor Selection:
- Pitfall : Using capacitors with insufficient voltage rating or high ESR
- Solution : Select capacitors with voltage ratings at least 1.5× the supply voltage and low ESR types
Output Regulation:
- Pitfall : Poor load regulation under varying current demands
- Solution : Implement post-regulation with LDOs for critical applications or use larger pump capacitors
Noise Sensitivity:
- Pitfall : Clock noise coupling into sensitive analog circuits
- Solution : Use shielded layouts, separate analog and digital grounds, and add filtering capacitors
### Compatibility Issues with Other Components
Digital Circuits:
- May introduce switching noise into sensitive digital ICs
- Mitigation : Physical separation and proper decoupling
Analog Circuits:
- Switching noise can affect precision analog components
- Mitigation : Use LC filtering and consider linear regulators for noise-sensitive applications
Microcontrollers:
- Ensure the converter's switching frequency doesn't interfere with crystal oscillators or communication frequencies
### PCB Layout Recommendations
Component Placement:
- Place pump capacitors (C1, C2) as close as possible to the IC pins
- Position output capacitor (C3) near the output pin and load
- Keep sensitive analog circuits away from the converter
Routing Guidelines:
- Use short, wide traces for pump capacitor connections
- Implement separate ground planes for analog and digital sections
- Route output traces away from sensitive input signals
Thermal Management:
- Provide adequate copper area for heat dissipation under high load conditions
- Consider thermal vias for improved heat transfer in multilayer boards
## 3. Technical Specifications
### Key Parameter Explanations
Supply Voltage Range: 1.5V to 10V
- Determines the input operating range and maximum output voltage capability
Output Voltage: -VIN to +2VIN
- Voltage inversion or doubling capability based on configuration
