P87C552 NXP Semiconductors, P87C552 Datasheet - Page 22

• Manufacturer Part Number: P87C552
• Description: The 87C552 Single-Chip 8-Bit Microcontroller is manufactured in anadvanced CMOS process and is a derivative of the 80C51microcontroller family
• Manufacturer: NXP Semiconductors

Philips Semiconductors
10-Bit Analog-to-Digital Conversion: Figure 20 shows the
elements of a successive approximation (SA) ADC. The ADC
contains a DAC which converts the contents of a successive
approximation register to a voltage (VDAC) which is compared to
the analog input voltage (Vin). The output of the comparator is fed to
the successive approximation control logic which controls the
successive approximation register. A conversion is initiated by
setting ADCS in the ADCON register. ADCS can be set by software
only or by either hardware or software.
2003 Apr 01
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I
capture/compare, high I/O, low voltage (2.7 V to 5.5 V), low power
ADC0
ADC1
ADC2
ADC3
ADC4
ADC5
ADC6
ADC7
ADCON
0
ANALOG INPUT
MULTIPLEXER
1
f
1/2
OSC
2
Figure 18. Functional Diagram of Pulse Width Modulated Outputs
3
Figure 19. Functional Diagram of Analog Input Circuitry
4
PRESCALER
PWMP
5
2
C, PWM,
6
7
INTERNAL BUS
10-BIT A/D CONVERTER
8-BIT COMPARATOR
8-BIT COMPARATOR
0
22
8-BIT COUNTER
The software only start mode is selected when control bit ADCON.5
(ADEX) = 0. A conversion is then started by setting control bit
ADCON.3 (ADCS). The hardware or software start mode is selected
when ADCON.5 = 1, and a conversion may be started by setting
ADCON.3 as above or by applying a rising edge to external pin
STADC. When a conversion is started by applying a rising edge, a
low level must be applied to STADC for at least one machine cycle
followed by a high level for at least one machine cycle.
1
PWM0
PWM1
2
3
4
5
6
OUTPUT
OUTPUT
BUFFER
BUFFER
7
ADCH
+
–
STADC
ANALOG REF.
ANALOG SUPPLY
ANALOG GROUND
SU00956
PWM0
PWM1
SU00957
P87C552
Product data