LMH6644 operational amplifier chip

Product description

The LMH6644 is a four-channel voltage feedback high-speed rail-to-rail output operational amplifier for the Antminer S21+ Hydro hash board. This single-chip integrates four independent op-amps and is specifically designed for high-speed signal sampling, current detection, and signal buffering circuits in ASIC hash chips. It is widely compatible with the signal-conditioning circuit on the Antminer S21+ Hydro hash board and is a core component for voltage sampling, feedback control, and signal amplification.

The chip features a 130MHz bandwidth, 135V/μs slew rate, and a single-channel 75mA high-current output capability. It operates on a wide voltage range of 2.7V~12.8V from a single power supply, exhibiting low distortion and low quiescent power consumption. Its rail-to-rail output can output a complete signal within 40mV of the power rail, ensuring attenuated transmission of weak sampling signals from the hash chip.

In the Antminer S21+ Hydro hash board circuit, the LMH6644 is responsible for buffering, amplifying, and filtering the current and voltage sampling signals of the ASIC chip. It acquires real-time operating voltage and load current analog signals from the ASIC chip, normalizes them into standard voltage signals, and sends them back to the main control MCU to complete closed-loop voltage regulation, overvoltage and overcurrent protection, and computing power monitoring.

Core electrical parameters:

Channel Specifications: 4 independent operational amplifiers (SOIC14 surface mount package)

Gain-bandwidth product: 130MHz (voltage gain 1x)

Slew rate: 135V/μs, no waveform distortion for high-speed signals

Linear output current: 75mA per channel, peak short-circuit current 115mA

Power supply range: 2.7V~12.8V single power supply, compatible with 5V power supply circuits for mining boards

Output swing: Only 40mV from the power rail, complete rail-to-rail output

Single channel quiescent current: 2.7mA, low heat generation, suitable for water-cooled, enclosed environments

Operating temperature: -40℃~+85℃, meets the requirements for long-term high-temperature operation of mining machines

Input offset voltage: Maximum 5mV, controllable sampling voltage error

Total harmonic distortion: -62dBc, low-interference amplification for weak computing signals

LMH6644 damaged / direct consequences of performance abnormalities:

Operational amplifier chip failure, internal channel breakdown, excessive offset drift, and open/short circuits in the output will directly lead to abnormal signal voltages in the S21+Hydro ASIC chip, resulting in overall system failure.

Repair and replacement tips:

1. Fault diagnosis: Use a multimeter to measure the voltages of the LMH6644's powering pins and input/output pins. If the output level is fixed and not correlated with the input signal, the chip is considered damaged.

2. Replacement standard: Only original LMH6644s must be used. Low-speed general-purpose operational amplifiers cannot be substituted, as insufficient bandwidth and output current will continue to cause abnormal ASIC chip signal voltages.

3. Soldering requirements: Use anti-static operation and low-temperature SOIC14 surface mount soldering to avoid damaging the PCB traces of the hash board with high temperatures.

4. Post-replacement verification: Test the sampling signal voltage of the computing chip under full load. If it returns to the standard range and the hash rate stabilizes, the repair is complete.

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Related product:

SGM8304YTS14

Antminer S21+ (plus) Hydro hash board accessory set