C8051F045 查看數據表（PDF） - Silicon Laboratories

零件编号

产品描述 (功能)

生产厂家

C8051F045

Mixed Signal ISP Flash MCU Family

Silicon Laboratories 

C8051F040/1/2/3/4/5/6/7

5.2. High-Voltage Difference Amplifier

The High Voltage Difference Amplifier (HVDA) can be used to measure high differential voltages up to 60 V

peak-to-peak, reject high common-mode voltages up to ±60 V, and condition the signal voltage range to be

suitable for input to ADC0. The input signal to the HVDA may be below AGND to –60 volts, and as high as

+60 volts, making the device suitable for both single and dual supply applications. The HVDA provides a

common-mode signal for the ADC via the High Voltage Reference Input (HVREF), allowing measurement

of signals outside the specified ADC input range using on-chip circuitry. The HVDA has a gain of 0.05 V/V

to 14 V/V. The first stage 20:1 difference amplifier has a gain of 0.05 V/V when the output amplifier is used

as a unity gain buffer. When the output amplifier is set to a gain of 280 (selected using the HVGAIN bits in

the High Voltage Control Register), an overall gain of 14 can be attained.

The HVDA uses four available external pins: +HVAIN, –HVAIN, HVCAP, and HVREF. HVAIN+ and HVAIN-

serve as the differential inputs to the HVDA. HVREF should be used to provide a common mode reference

for input to ADC0, and to prevent the output of the HVDA circuit from saturating. The output from the

HVDA circuit as calculated by Equation 5.1 must remain within the “Output Voltage Range” specification

listed in Table 5.3. The ideal value for HVREF in most applications is equal to 1/2 the supply voltage for the

device. When the ADC is configured for differential measurement, the HVREF signal is applied to the AIN-

input of the ADC, thereby removing HVREF from the measurement. HVCAP facilitates the use of a capac-

itor for noise filtering in conjunction with R7 (see Figure 5.3 for R7 and other approximate resistor values).

Alternatively, the HVCAP could also be used to access amplification of the first stage of the HVDA at an

external pin. (See Table 5.3 on page 68 for electrical specifications of the HVDA.)

VOUT = HVAIN+ – HVAIN-  Gain + HVREF

Note: The output voltage of the HVDA is selected as an input to the AIN+ input of ADC0 via its analog multiplexer

(AMUX0). HVDA output voltages outside the ADC’s input range will result in saturation of the ADC input. Allow

for adequate settle/tracking time for proper voltage measurements.

Equation 5.1. Calculating HVDA Output Voltage to AIN+

HVAIN-

k 5k

HVAIN+

100k 5k

Resistor values are

approximate

HVCAP

5k

HVA0CN

HVREF

Gain Setting

Vout

(To AMUX0)

Figure 5.3. High Voltage Difference Amplifier Functional Diagram

52

Rev. 1.5

Share Link: