P87C554 NXP Semiconductors, P87C554 Datasheet - Page 29

• Manufacturer Part Number: P87C554
• Description: The P87C554 Single-Chip 8-Bit Microcontroller is manufactured inan advanced CMOS process and is a derivative of the 80C51microcontroller family
• Manufacturer: NXP Semiconductors

Philips Semiconductors
2002 Mar 25
80C51 8-bit microcontroller – 12 clock operation
16K/512 OTP/RAM, 8 channel 10-bit A/D, I
capture/compare, high I/O
Rm = 0.5 - 3 k
C
R
NOTE:
Because the analog to digital converter has a sampled-data comparator, the input looks capacitive to a source. When a conversion
is initiated, switch Sm closes for 8t
should be noted that the sampling causes the analog input to present a varying load to an analog source.
S
S
+ C
= Recommended < 9.6 k for 1 LSB @ 12 MHz
C
= 15 pF maximum
R
V
S
in
– V
+
digital
CODE
OUT
CY
V
ANALOG
INPUT
(8 s @ 12 MHz crystal frequency) during which time capacitance C
Figure 26. Effective Conversion Characteristic
I
N+1
Figure 25. A/D Input: Equivalent Circuit
I
101
100
010
001
000
011
N
QUANTIZATION ERROR
SYMMETRICAL QUANTIZATION ERROR
0
2
q
C, PWM,
+ q/2
– q/2
Sm
Sm
C
S
N+1
N
MULTIPLEXER
2q
27
Rm
Rm
3q
q = LSB = 5 mV
N+1
N
4q
5q
V
V
C
in
in
C
TO COMPARATOR
SU00963
S
+ C
C
is charged. It
SU00962
P87C554
Product data