Part Number: C1237HA, uPC1237HA
Function: Protector IC for Stereo Power Amplifier
Package: SIP 8 Pin type.
Manufacturer: NEC
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Description
C1237HA is a monolithic integrated circuit designed for protecting stereo power amplifiers and loudspeakers. This is a monolithic protection IC developed by NEC for stereo audio power amplifiers and loudspeaker protection circuits. It integrates DC offset detection, AC power-off detection, relay driver control, power-on delay, and fault management into a single device. The IC helps prevent speaker damage caused by amplifier DC faults and suppresses turn-on/turn-off pop noise by controlling the speaker protection relay. It can be configured for either automatic reset or latch operation depending on the external connection at Pin 3.
Features
- Integrated speaker protection controller
- Designed for stereo power amplifiers
- Wide operating supply voltage: 25V to 60V
- Built-in relay driver
- Maximum relay drive current: 80mA
- Power-on delay function
- DC offset detection
- AC power failure detection
- Supports automatic reset or latch mode
- Single supply operation
- Reduces turn-on and turn-off pop noise
- Minimal external component count
Pinout
General Specifications
| Parameter | Specification | Unit |
| Device Type | Stereo Amplifier Protection IC | — |
| Supply Voltage | 25 to 60 | V |
| Relay Driver Output Current | 80 (max.) | mA |
| Power Supply | Single Supply | — |
| Protection Mode | Automatic Reset or Latch | Selectable |
Integrated Functions
- Power-on delay timer
- DC offset detection for left channel
- DC offset detection for right channel
- AC power-off detection
- Relay driver transistor
- Fault timing control
- Latch/Auto-reset controlOperating Principle
Design Notes
- The relay coil current must not exceed the IC’s maximum relay driver capability of 80mA. Larger relays require an external transistor.
- The startup delay is determined by an external RC timing network connected to the timing pin.
- DC detection thresholds depend on the external resistor-capacitor network and amplifier output coupling arrangement.
- Place AC detection components close to the power supply input to ensure fast response during mains interruption.
- Separate the high-current relay traces from low-level audio circuitry to minimize switching noise.
- Provide adequate decoupling of the supply pin for stable operation.
- The IC is intended for single-supply audio amplifier protection circuits operating from 25V to 60V.
Applications
- Consumer audio equipment
- Home Hi-Fi systems
- Professional sound systems
- PA amplifiers
- Car audio amplifiers (appropriate supply adaptation required)
- Powered loudspeakers
- Audio repair and retrofit projects
Alternative / Equivalent Products
- UPC1237
- μPC1237HA
- AN7062
- TA7317P
- LM391-based protection circuits (discrete implementation)
- Speaker protection modules using LM339 comparators
C1237HA Datasheet
