SNAD01B
8-CHANNEL 8-BIT ADC
========
1.
2.
3.
4.
5.
6.
CONTENTS
========
GENERAL DESCRIPTION.......................................................................................................................................3
FEATURES....................................................................................................................................................................3
APPLICATIONS ..........................................................................................................................................................3
BLOCK DIAGRAM.....................................................................................................................................................4
PIN ASSIGNMENT......................................................................................................................................................4
FUNCTIONAL DESCRIPTIONS .............................................................................................................................5
I
NTERFACE
F
ORMAT
.............................................................................................................................................................5
C
HANNEL
S
ETTING
...............................................................................................................................................................7
C
ONTROL
R
EGISTER
S
ETTING
..............................................................................................................................................7
ADC R
EAD
T
IMING
..............................................................................................................................................................8
T
IMING OF
D
IGITAL
I
NPUT
R
EADING
...................................................................................................................................9
P
OWER
D
OWN
& C
HANNEL
W
AKE
-U
P
.............................................................................................................................10
B
ANDGAP REFERENCE
........................................................................................................................................................11
I
NPUT
C
HANNEL
PAD (C
HANNEL
0~6) ............................................................................................................................12
B
ATTERY
M
ONITORING
(C
HANNEL
7
ONLY
) ....................................................................................................................13
7.
8.
9.
ELECTRICAL CHARACTERISTICS ..................................................................................................................14
APPLICATION CIRCUITS .....................................................................................................................................15
E
XAMPLE
C
IRCUIT
: SNAD01B
WORKS WITH
S
ONIX
4-
BIT
S
ERIES
C
ONTROLLER
..........................................................15
EXAMPLE PROGRAMS:........................................................................................................................................16
P
ROGRAM
1: S
ET
C
ONFIGURATION OF
SNAD01B..........................................................................................................27
P
ROGRAM
2: R
EAD
ADC
RESULT FROM
C
HANNEL
1 ......................................................................................................27
P
ROGRAM
3: R
EAD
D
IGITAL
I
NPUT DATA FROM
C
H
4, C
H
3, CH2 ..................................................................................28
P
ROGRAM
4: P
OWER
-
DOWN
SNAD01B
AND
H
OST
,
AND
W
AKE
-
UP
..............................................................................28
P
ROGRAM
5: B
ATTERY
L
OW
D
ETECTION
.........................................................................................................................29
10.
PAD DIAGRAM...................................................................................................................................30
Version: 1.3
1
July 31, 2003
SNAD01B
8-CHANNEL 8-BIT ADC
AMENDMENT HISTORY
Version
Date
Ver 1.1 February 12, 2003
Ver 1.3 July 31, 2003
Description
First issue.
1. Add the version code “B” of chip no.
2. This spec is modified form SNAD01_V1.3
3. Add standby current more than 50 uA in page 10
Note: This document is used to identify the different version “B” & “C” of SNAD01, the most
important is standby current and power down setting between version “B” & “C”. For the detail
please refer to related section.
Version: 1.3
2
July 31, 2003
SNAD01B
8-CHANNEL 8-BIT ADC
1. GENERAL DESCRIPTION
SNAD01B is a low cost serial 8-bits ADC with 8 individual input channels. Each channel can
be independently programmed to a digital or analog input mode. In the analog input mode, this
single-ended channel accepts an analog input signal from 0 to V
REF
and converts the signal into
12-bit digital codes (with 8-bit accuracy guaranteed). In the digital input mode, the channel can be
treated as digital input port and the logic level appears at the channel can be acquired. SNAD01B
has a synchronous 3-wires serial interface. Through this interface, the host CPU can easily control
SNAD01B.
During A-to-D conversion, the typical current consumption is 500uA at 25kHz throughput-rate
and +3V power supply. SNAD01B includes a power-down mode, which reduces maximum current
consumption to less than 1uA.
The reference voltage can be varied between 1V and +V
CC
, providing a corresponding input
voltage range of 0V to V
REF
. SNAD01B also has an on-chip 1.17V bandgap reference that can be
utilized for constant voltage input (especially for battery monitoring applications). The bandgap
reference circuitry consumes 300µA@3v and can be enabled and disabled.
2. FEATURES
♦
Single Supply: 2.7V ~ 5.25V
♦
Eight Analog/Digital Input Channels.
♦
Internal 1.17v Bandgap Reference for Battery Monitoring. (Channel 7)
♦
Low Power Consumption: typical operating current: 500uA @ 3V, Standby current <1uA.
♦
Up to 25kHz Conversion Rate.
♦
8-bits Resolution with (8-bits) No Missing Code.
♦
3-Wire Serial Interface.
3. APPLICATIONS
♦
Battery-Powered Systems
♦
Instrumentation
♦
Portable Data Logging
♦
Test Equipment
♦
Data Acquisition
♦
Process-Control Monitoring
Version: 1.3
3
July 31, 2003
SNAD01B
8-CHANNEL 8-BIT ADC
♦
Digital Input Bus Extender
4. BLOCK DIAGRAM
AVDD
VDDD
1.2V Bandgap
Reference
VRH
CH0/DI0
CH1/DI1
CH2/DI2
CH3/DI3
CH4/DI4
CH5/DI5
CH6/DI6
CH7(BAT)/DI7
8-Channels
Analog/Digital
Input MUX
8-bit SAR
ADC
Serial
Interface
and
Control
Logic
START
CLK
DIO
AVSS
VSSD
Figure1 Block diagram of ADC.
5. PIN ASSIGNMENT
Pin Name
CH[7] ~ CH[0]
REF
VDD
VSS
AVDD
AVSS
START
CLK
DIO
I/O
I
I
I
I
I
I
I
I
IO
Description
Analog input / digital input
Reference voltage of analog signal
Positive power
Negative power
Positive power of analog circuit
Negative power of analog circuit
Command initialization signal (from host
controller)
Clock of data communication and AD
conversion (from host controller)
Data input and output of data communication
Version: 1.3
4
July 31, 2003
SNAD01B
8-CHANNEL 8-BIT ADC
6. Functional Descriptions
VDD
Host CPU
Output Port1
Output Port2
I/O port
START
CLK
DIO
START
CLK
DIO
SNAD01
VDD
AVDD
REF
0.1uF
VSS
`
AVSS
CH[0]
CH[1]
Analog/Digital
Signal
CH[7]
Figure2 Interface with Host CPU
Interface Format
START
CLK
Channel Setting
HiZ
DIO
CM2 CM1 CM0 CH[7] CH[6] CH[5] CH[4] CH[3] CH[2] CH[1] CH[0]
Port Input
PH
PL
RF
MB
xx
xx
xx
Port Input
xx
D7
D6
D5
D4
Port Output
D3
xx
xxx
Control Register Setting
DIO
HiZ
CM2 CM1 CM0
xxx
ADC Reading
HiZ
DIO
CM2 CM1 CM0 ID2 ID1 ID0
Port Input
Digital Input Reading
HiZ
DIO
CM2 CM1 CM0 DI[7] DI[6] DI[5]
Power Down
HiZ
DIO
Port Input
CM2 CM1 CM0
Port Input
D2
D1
D0
DI4]
DI[3] DI[2] DI[1] DI[0] DI[7] DI[6] DI[5]
Port Output
DI4]
DI[3]
PDS
Port Output
~PDS
Figure3 Timing Diagram of Whole Commands
Version: 1.3
5
July 31, 2003
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