XA-S3 Datasheet, PDF (16/52 Pages) NXP Semiconductors – XA 16-bit microcontroller 32 K/1 K OTP/ROM/ROMless, 8-channel 8-bit A/D, low voltage 2.7 V.5.5 V, I2C, 2 UARTs, 16 MB address range

Philips Semiconductors
XA 16-bit microcontroller
32 K/1 K OTP/ROM/ROMless, 8-channel 8-bit A/D, low voltage (2.7 V–5.5 V),
I²C, 2 UARTs, 16 MB address range
Preliminary specification
XA-S3
Table 3. A/D Timing Configuration for 10-bit Mode
ADCFG.3–0
Max. Oscillator
Frequency (MHz)
Conversion Time
Osc. Clocks
µsec at max. Osc.
0h (0000)
6.66
88
13.21
1h (0001)
8
92
9.2
2h (0010)
8
96
8.64
3h (0011)
12
116
8.7
4h (0100)
12
120
7.2
5h (0101)
12
124
6.2
6h (0110)
12
136
6.8
7h (0111)
12
128
5.77
8h (1000)
13
148
6.35
9h (1001)
13
152
5.71
Ah (1010)
13
156
5.2
Bh (1011)
13
170
5.67
Ch (1100)
13
160
5.0
Dh (1101)
16
180
5.41
Eh (1110)
20
204
5.57
Fh (1111)
20
208
5.2
Sampling Time
(Osc. Clocks)
4
6
8
8
10
12
24
14
14
16
18
32
20
20
22
24
A/D Inputs
In order to obtain accurate measurements with the A/D Converter,
the source drive must be sufficient to adequately charge the
sampling capacitor during the sampling time. Figure 4 shows the
equivalent resistance and capacitance related to the A/D inputs.
A/D timing configurations indicated in Table 1 allow for full A/D
accuracy (according to the A/D specifications) assuming a source
resistance of less than or equal to 20kΩ. Larger source resistances
may be accommodated by increasing the sampling time with a
different A/D timing configuration.
AD_N+1
Sm_N+1 Rm_N+1
AD_N
Sm_N
Rm_N
TO COMPARATOR
+
Multiplexer
R_S
V_ANALOG
C_S
C_C
INPUT
R_m (multiplexer resistance)
C_S (pin capacitance)
C_C (sampling capacitor)
R_S (source resistance)
= 3 kΩ maximum
= 10 pF maximum
= 2 pF maximum
= Recommended less than 20kΩ for full specified accuracy. This allows time for the sampling
capacitor (C_C) to fully charge while the multiplexer switch is closed. Please note that sampling
causes the analog input to present a varying load to the pin.
SU00948
Figure 4. A/D Input: Equivalent Circuit
2000 Dec 01
16