ICmic
TM
IC MICROSYSTEMS
ICM7912
12-
BIT
125
K
SPS SAR ADC
FEATURES
•
•
•
•
•
•
•
•
•
12-Bit SAR ADC
125kSPS sampling rate
Single supply single channel
Low power dissipation 1.9mW
Shutdown feature
Flexible serial interface
Supply voltage of 2.7V to 5.5V
Temperature range: −40°C to +85°C
8-lead TSSOP
OVERVIEW
The ICM7912 is a 12-bit 125kSPS through put rate
Analog-to-Digital Converter with a unipolar,
single-ended input. It has successive approximation
register (SAR) architecture and can sample the
analog input. It has a flexible serial interface.
APPLICATIONS
•
•
•
•
•
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PDA’s
Touch screen monitors
Hand held devices
Instrumentation and control systems
Data Acquisition Systems
Automotive
BLOCK DIAGRAM
REFIN
VIN
ICM7912
R-DAC
C-DAC
COMPARATOR
Successive Approximation Register (SAR)
DOUT
CSB
DCLK
BUSY
Rev 0.1
ICmic reserves the right to change the specifications without prior notice.
1
ICmic
TM
IC MICROSYSTEMS
ICM7912
12-
BIT
125
K
SPS SAR ADC
PACKAGE
8-Pin TSSOP
VREF
AIN
VDD
GND
CSB
BUSY
DOUT
DCLK
PIN DESCRIPTION
Pin No
1
2
3
4
5
6
7
8
Symbol
VREF
AIN
VDD
GND
DCLK
DOUT
BUSY
CSB
Description
Reference input
Analog Input
Power Supply Input. Range is from 2.7V to 5.5V
Ground
External CLK Input
Serial Data output, clocked out on falling edge of CLK
BUSY output
Chip Select input Active Low. Initiates conversion and enables serial data.
ABSOLUTE MAXIMUM RATING
Symbol
V
DD
I
IN
V
IN_
V
IN_REF
T
STG
T
SOL
Parameter
Supply Voltage
Input Current
Digital Input Voltage
Reference Input Voltage
Storage Temperature
Soldering Temperature
Value
-0.3 to 6.0
+/- 100.0
-0.3 to 6.0
-0.3 to 6.0
-65 to +150
300
Unit
V
mA
V
V
o
C
o
C
Note:
Stress greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the
device. This is a stress rating only and functional operation of the device at these or any other conditions above those
indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions
for extended periods may affect reliability
.
ORDERING INFORMATION
Part
ICM7912
Rev 0.1
Temperature Range
-40 C to 85 C
o
o
Package
8-Pin TSSOP
ICmic reserves the right to change the specifications without prior notice.
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ICmic
TM
IC MICROSYSTEMS
DC ELECTRICAL CHARACTERISTICS
ICM7912
12-
BIT
125
K
SPS SAR ADC
(VDD= 3.5V, Maximum Sample Rate, REF
=
2.5V; all specifications T
MIN
to T
MAX
unless otherwise noted)
Symbol
Parameter
Test Conditions
DC PERFORMANCE
Min
Typ
Max
Unit
N
No
Missing
Codes
INL
GE
OE
VDD
I
VDD
I
SHTDOWN
Resolution
(Note 1)
(Note 1)
12
12
0.25
1
30
2.7
600
40
5.5
Bits
Bits
% of FSR
% of FS
mV
V
µA
µA
Integral Nonlinearity
Gain Error
Offset Error
Supply Voltage
Supply Current
Supply Current
(Note 1)
(Note 1)
(Note 1)
POWER REQUIREMENTS
(Note 2)
(Note 1)
(Note 1)
Symbol
VIH
VIL
VOH
VOL
Fsample
TCLK
Parameter
Test Conditions
Min
Typ
Max
Unit
V
V
V
V
kSPS
kSPS
ns
ns
ns
ns
ms
kΩ
V
µA
LOGICINPUT/OUTPUT CHARACTERISTICS (VDD = 2.5V)
2.4
0.4
(Note 1)
2.4
IOH = 50
µΑ
(Note 1)
IOL = 50
µΑ
SWITCHING SPECIFICATIONS (CLK INPUT)
Maximum Conversion Rate
(Note 2)
Minimum Conversion Rate
(Note 2)
0.5
CLK Period
(Note 2)
500
Pulse-width High
(Note 2)
250
Pulse-width Low
(Note 2)
250
Data out Delay
(Note 2)
Wake-up Time
(Note 2)
REFERENCE
Reference Input Resistance
(Note 1)
Reference Input Span
Reference Input Current
0.4
125
T
Delay
5
20
32
VDD
80
R
IN
I
REF
Note 1: 100 % Production Tested at 25 C; guaranteed by design and characterization testing for temperature range.
Note 2: Guaranteed by design& characterization testing.
Note 3: See Applications Information.
Note 4: 12 Monotonicity only guaranteed at REFIN MAX of VDD-1. Reference Input can swing to a higher value till
VDD, with some degradation in DC performance and monotonicity could degrade to only 11 bits at high reference input.
Rev 0.1
ICmic reserves the right to change the specifications without prior notice.
3
ICmic
TM
IC MICROSYSTEMS
TIMING DIAGRAM
CSB
ICM7912
12-
BIT
125
K
SPS SAR ADC
1
DCLK
16
BUSY
DOUT
MSB
LSB
DETAILED DESCRIPTION
The ICM7912 is a SAR architecture 12-Bit ADC. It
operates on a 2.7V to 5.5V single supply and
consumes about 600µA supply current when
operating on a 2MHz external clock. The output
throughput rate is a maximum of 125 kSPS when
the DCLK is running at at the maximum frequency
of 2MHz.
The ADC is composed of a high performance
capacitive DAC and a comparator along with SAR
control logic and resistor string segment. The
reference input drives the resistor string directly
and has an input resistance of around 32 kΩ.
The ICM7912 comes complete with a high
performance CMOS sample and hold amplifier
made up by the capacitive DAC.
There is shutdown capability which is active
between conversions when CSB is high. The
converter will shut down to under 40
µA
of supply
current.
The ICM7912uses the DCLK as the external clock
and this controls all the transfer of information to
and from the ADC.
One complete conversion cycle of the ICM7912
will take 16 clock cycles. As CSB is pulled low the
ADC
powers
up
and
initiates
a
sampling/conversion cycle. Data is clocked out
MSB first on the falling edge of the DCLK input.
The analog input is sampled on the first three clock
pulses and then conversion process begins. The
DOUT is available from the falling edge of the 4
th
DCLK pulse MSB first and the LSB is available on
the falling edge of the 15
th
DCLK pulse. Since there
is some propagation delay the DOUT should be
sampled on the rising edge of the following clock
pulse. So this implies the MSB can be safely
sampled on the 5
th
DCLK rising edge and the LSB
can be sampled on the 16
th
DCLK rising edge.
APPLICATIONS INFORMATION
The IC7912 has a single ended analog input which
can swing from GND to VDD. The reference input
has a range from GND to VDD and can be tied to
VDD for largest input range.
Rev 0.1
ICmic reserves the right to change the specifications without prior notice.
4
ICmic
TM
IC MICROSYSTEMS
PACKAGE INFORMATION
8 LEAD TSSOP STANDARD PACKAGE
ICM7912
12-
BIT
125
K
SPS SAR ADC
Rev 0.1
ICmic reserves the right to change the specifications without prior notice.
5
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