C8051F047R Silicon Labs, C8051F047R Datasheet - Page 52

• Manufacturer Part Number: C8051F047R
• Description: 8-bit Microcontrollers - MCU 25 MIPS 32KB 10ADC
• Manufacturer: Silicon Labs

Specifications of C8051F047R

• Product Category: 8-bit Microcontrollers - MCU
• Core: 8051
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 25 MHz
• Program Memory Size: 32 KB
• Data Ram Size: 4.25 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 2.7 V to 3.6 V
• Package / Case: TQFP-64
• Mounting Style: SMD/SMT
• A/d Bit Size: 10 bit
• A/d Channels Available: 13
• Data Rom Size: 64 KB
• Interface Type: CAN, SMBus, SPI, UART
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 32
• Number Of Timers: 16 bit
• Processor Series: C8051
• Program Memory Type: Flash
• Factory Pack Quantity: 500
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 2.7 V

C8051F040/1/2/3/4/5/6/7
5.2.
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.)
Note: The output voltage of the HVDA is selected as an input to the AIN+ input of ADC0 via its analog multiplexer
52
HVAIN+
HVAIN-
(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.
High-Voltage Difference Amplifier
Figure 5.3. High Voltage Difference Amplifier Functional Diagram
Resistor values are
Equation 5.1. Calculating HVDA Output Voltage to AIN+
approximate
V
k
100k
OUT
=
5k
5k


HVAIN+
HVREF

–
Rev. 1.5

HVAIN-
HVA0CN

 Gain
5k

HVCAP
+
Gain Setting
HVREF
(To AMUX0)
Vout