z89136 ZiLOG Semiconductor, z89136 Datasheet - Page 8

• Manufacturer Part Number: z89136
• Description: Low-cost Dtad Controller
• Manufacturer: ZiLOG Semiconductor

Z89135/136 (ROMless)
Low-Cost DTAD Controller
A/D CONVERTER (ADC)
Figure 4 shows the input circuit of the ADC. When conver-
sion starts, the analog input voltage from the input is con-
nected to the MSB and LSB flash converter inputs as
shown in the Input Impedance CKT diagram. Shunting 31
parallel internal resistances of the analog switches and si-
multaneously charging 31 parallel 1 pF capacitors is equiv-
alent to a 400 Ohms input impedance in parallel with a 31
pF capacitor. Other input stray capacitance adds about 10
ABSOLUTE MAXIMUM RATINGS
Symbol
V
T
T
Notes:
Voltage on all pins with respect to GND.
† See Ordering Information.
1-8
A
STG
CC
Oper Ambient Temp
Supply Voltage (*)
Storage Temp
Description
C Parasitic
R Source
–65
–0.3
Min
Figure 4. Input Impedance of ADC
+150
Max
+7.0
on Resistance
CMOS Switch
†
2 - 5 k
P R E L I M I N A R Y
V Ref
V Ref
V Ref
Units
V
C
C
pF to the input load. Input source resistances up to 2 Ko-
hms can be used under normal operating conditions with-
out any degradation of the input settling time. For larger in-
put source resistance, longer conversion cycle times may
be required to compensate the input settling time problem.
V
Stresses greater than those listed under Absolute Maxi-
mum Ratings may cause permanent damage to the de-
vice. This is a stress rating only; operation of the device at
any condition above those indicated in the operational sec-
tions of these specifications is not implied. Exposure to ab-
solute maximum rating conditions for an extended period
may affect device reliability.
C .5 pF
C .5 pF
C .5 pF
REF
is set using the V
REF
31 CMOS Digital
Comparators
+ pin.
DS97TAD0300
Zilog