80C554 Datasheet, PDF (28/76 Pages) NXP Semiconductors – 80C51 8-bit microcontroller . 6 clock operation 16K/512 OTP/ROM/ROMless, 7 channel 10 bit A/D, I2C, PWM, capture/compare, high I/O, 64L LQFP

Philips Semiconductors
80C51 8-bit microcontroller – 6 clock operation
16K/512 OTP/ROM/ROMless, 7 channel 10 bit A/D, I²C, PWM,
capture/compare, high I/O, 64L LQFP
Preliminary specification
80C554/83C554/87C554
I_N+1
+
R_S
I_N
V_ANALOG
INPUT
Sm_N+1 Rm_N+1
Sm_N
Rm_N
MULTIPLEXER
C_S
TO COMPARATOR
C_C
Rm = 0.5 - 3 kΩ
C_S + C_C = 15 pF maximum
R_S = Recommended < 9.6 kΩ for 1 LSB @ 12 MHz
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_CY (4 µs @ 12 MHz crystal frequency) during which time capacitance C_S + C_C is charged. It
should be noted that the sampling causes the analog input to present a varying load to an analog source.
SU01449
Figure 25. A/D Input: Equivalent Circuit
CODE
OUT
V_in – V_digital
101
100
011
010
001
000
0
q
2q
QUANTIZATION ERROR
3q
4q
5q
V_in
q = LSB = 5 mV
+ q/2
2000 Nov 10
– q/2
V_in
SYMMETRICAL QUANTIZATION ERROR
Figure 26. Effective Conversion Characteristic
SU00963
28