9.2.2 CPU/GPU Supply Voltage Monitoring

Under-voltage monitoring for CPU or GPU is essential for maintaining system stability and shutdown due to low

voltage in modern computing applications.

9.2.2.1 Detailed Design Procedure

The Figure 9-3 shown demonstrates a classic under-voltage detection scheme where the CPU/GPU supply

voltage (VCC) is monitored through a difference amplifier that scales the input to compare with a reference level

in next stage using comparator. The difference amplifier is usually in unity gain configuration. When VCC drops

below the predetermined threshold, the comparator output switches states to trigger protective actions such as

system shutdown, frequency throttling, or voltage regulation adjustments.

R

1

R

1

R

2

R

2

GND

V

CC

Out

GND

GND

CPU/GPU

V

DD

+

–

OPA620

Figure 9-3. Voltage Monitoring Circuit

9.2.3 Driving Analog-to-Digital Converters

9.2.3.1 Detailed Design Procedure

The OPA620 series op amps offer 60ns of settling time to 0.01%, making the series a good choice for driving

high- and medium-speed sampling ADCs and reference circuits. The OPA620 series provide an effective means

of buffering the ADC input capacitance and resulting charge injection while providing signal gain. OPA620 is an

excellent choice for applications requiring high dc accuracy.

Figure 9-4 shows the OPA620 driving an ADC. With the OPA620 in an inverting configuration, a capacitor across

the feedback resistor is used to filter high-frequency noise in the signal

ADS7816, ADS7861, or

ADS7864 12-Bit ADC

OPA620

V+

+IN

V–

2.5V

330pF

VIN

–IN

VREF

5k

5k

5V

GND

Figure 9-4. The OPA620 in Inverting Configuration Driving the ADS7816

1.

ADC input = 0V to VREF.

2.

VIN = 0V to –5V for 0V to 5V output.

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OPA620

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