DUAL RECORDING AND PLAYBACK PRE-AMPLIFIER IC FOR SINGLE/DOUBLE CASSETTE# AN7316 Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The AN7316 is a monolithic integrated circuit designed primarily as a preamplifier for magnetic cartridge systems in audio applications. Its primary use cases include:
- Phono Equalization Amplifiers : Providing RIAA equalization for vinyl record playback systems
- Magnetic Cartridge Signal Conditioning : Amplifying low-level signals from magnetic phono cartridges (typically 2-5 mV)
- Audio Preamplifier Stages : Serving as the initial amplification stage in high-fidelity audio systems
### Industry Applications
- Consumer Audio Equipment : Hi-fi systems, turntables, and integrated amplifiers
- Professional Audio Gear : DJ mixers, studio preamplifiers, and audio interfaces with phono inputs
- Vintage Audio Restoration : Replacement for obsolete phono preamplifier ICs in classic audio equipment
- Custom Audio Projects : DIY audio enthusiasts building custom phono stages
### Practical Advantages
Strengths:
- Low Noise Operation : Typical noise voltage of 0.3 μV, making it suitable for sensitive audio applications
- High Gain Capability : Provides approximately 40 dB gain at 1 kHz, adequate for most magnetic cartridges
- Simple Implementation : Requires minimal external components for basic operation
- Cost-Effective Solution : Economical alternative to discrete component designs
- Temperature Stability : Good performance consistency across operating temperature ranges
Limitations:
- Frequency Response : Specifically optimized for RIAA equalization, limiting general-purpose use
- Supply Voltage Range : Restricted to maximum ±18V, constraining dynamic headroom
- Output Current : Limited output drive capability (typically 5 mA), requiring buffer stages for low-impedance loads
- Aging Components : As a legacy component, availability may be limited compared to modern alternatives
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Power Supply Decoupling
- Pitfall : Inadequate decoupling causing oscillation and noise
- Solution : Use 100 μF electrolytic and 0.1 μF ceramic capacitors at each supply pin, placed close to the IC
Grounding Issues
- Pitfall : Poor ground layout introducing hum and noise
- Solution : Implement star grounding with separate analog and power grounds meeting at the power supply
Gain Setting
- Pitfall : Incorrect feedback network values causing improper RIAA equalization
- Solution : Use 1% tolerance resistors and film capacitors in the feedback network for accurate response
### Compatibility Issues
Cartridge Matching
- Issue : Mismatch between cartridge impedance and amplifier input characteristics
- Resolution : Include loading networks (typically 47kΩ resistor parallel with 100-470pF capacitor) at input
Modern Source Integration
- Issue : Interface with digital systems and higher-level signals
- Resolution : Add output attenuation networks or buffer amplifiers when connecting to line-level inputs
Power Supply Compatibility
- Issue : Modern switching power supplies may introduce high-frequency noise
- Resolution : Implement additional LC filtering on supply rails
### PCB Layout Recommendations
Critical Layout Practices:
- Component Placement : Keep feedback and input components close to the IC pins
- Signal Routing : Use ground planes and keep audio traces short and direct
- Thermal Management : Provide adequate copper area for heat dissipation, though power dissipation is typically low
- Shielding : Consider shielding cans in high-noise environments
Specific Guidelines:
```
Input Section:
- Keep input traces as short as possible
- Shield input cables and use twisted pairs
- Place input loading components directly at the input pin
Feedback Network:
- Position RIAA equalization components adjacent to the IC
- Minimize trace lengths in
