NEC

C1237HA Datasheet – SIP 8 Pin, uPC1237HA, Protector IC – NEC

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Part Number: C1237HA, uPC1237HA

Function: Protector IC for Stereo Power Amplifier

Package: SIP 8 Pin type.

Manufacturer: NEC

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C1237HA protector

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

C1237HA datasheet 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

2SD822 Transistor – 600V, 7A, NPN Transistor

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What is 2SD822?

This is high-voltage NPN silicon power transistor.

Function: 600V, 7A, Silicon NPN Transistor

Package: TO-126 Type

Manufacturer: Toshiba

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2SD822 datasheet pdf

Description

The 2SD822 is a high-voltage NPN silicon power transistor specifically designed for horizontal output applications in CRT color televisions. It is optimized for high-voltage switching, fast transition times, and robust operation under inductive load conditions. With a collector-base voltage rating up to 1500V and strong switching performance, it is well-suited for flyback transformer drive circuits and similar high-energy pulse applications.

Features

  • High collector-base voltage capability (VCBO = 1500V)
  • High-speed switching (tf ≈ 1.0µs max)
  • Low collector-emitter saturation voltage
  • Glass-passivated collector-base junction for improved reliability
  • Designed for high-voltage pulse and inductive load operation
  • Good ruggedness under flyback conditions

Pinout

2SD822 pinout

Typical Application Context

  • CRT horizontal deflection output stage
  • Flyback transformer driver circuits
  • High-voltage pulse generators
  • Switching power stages with inductive loads

Absolute Maximum Ratings (Ta = 25 °C)

Parameter Symbol Value Unit
Collector-Base Voltage VCBO 1500 V
Collector-Emitter Voltage VCEO 600 V
Emitter-Base Voltage VEBO 5 V
Collector Current IC 7 A
Emitter Current IE -7 A
Power Dissipation (Tc = 25°C) PC 50 W
Junction Temperature Tj 150 °C
Storage Temperature Tstg -55 to 150 °C

Design Notes

  • Optimized for flyback operation — capable of handling high voltage spikes generated by transformer collapse
  • Fast fall time (tf) is critical for minimizing switching loss in horizontal deflection circuits
  • Requires proper snubber or damper network to control voltage overshoot
  • Base drive must be sufficiently strong (e.g., IB ≈ IC/5) to ensure deep saturation during switching
  • Thermal design is essential due to high pulse energy and switching stress

Typical Circuit Usage

  • CRT horizontal output transistor (HOT stage)
  • Flyback transformer switching
  • High-voltage pulse switching circuits
  • Inductive load switching with high dv/dt stress

How to Choose This Part

  • Select for high-voltage (>600V) switching environments
  • Ideal for legacy CRT or flyback-based designs
  • Ensure proper base drive and protection network design
  • Evaluate switching speed vs modern MOSFET/IGBT alternatives
  • Confirm thermal and SOA margins under pulsed conditions

Applications

  • Color TV horizontal output stages
  • High-voltage switching circuits
  • Flyback power supplies
  • Pulse power systems
  • Industrial high-voltage drivers

Alternative / Equivalent Products

  • BU508A (common HOT transistor alternative)
  • 2SD1555 (similar high-voltage transistor)
  • 2SC5388 (modern replacement option)
  • BU2520AF (integrated damper diode type)
  • IGBT or MOSFET replacements (depending on topology redesign)

2SD822 Datasheet PDF Download

2SD822 pdf