LINER LTC1096LACS8 Low voltage, micropower sampling 8-bit serial i/o a/d converter Datasheet

Final Electrical Specifications
LTC1096L/LTC1098L
Low Voltage, Micropower
Sampling 8-Bit Serial I/O
A/D Converters
December 1995
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DESCRIPTIO
FEATURES
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The LTC®1096L/LTC1098L are 3V micropower, 8-bit successive approximation sampling A/D converters. They
typically draw only 40µA of supply current when converting and automatically power down to a typical supply
current of 1nA between conversions. They are packaged in
8-pin SO packages and operate on a 3V supply. These 8bit, switched capacitor, successive approximation ADCs
include a sample-and-hold. The LTC1096L has a single
differential analog input. The LTC1098L offers a software
selectable 2-channel multiplexed input.
Specified at 2.65V Minimum Supply
Maximum Supply Current: 80µA
Auto Shutdown to 1nA
8-Pin SO Package
On-Chip Sample-and-Hold
Conversion Time: 32µs
Sample Rates: 16.5ksps
I/O Compatible with SPI, MICROWIRETM, etc.
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APPLICATI
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On-chip serial ports allow efficient data transfer to a wide
range of microprocessors and microcontrollers over three
wires. This, coupled with micropower consumption, makes
remote location possible and facilitates transmitting data
through isolation barriers.
Battery-Operated Systems
Remote Data Acquisition
Isolated Data Acquisition
Battery Monitoring
Temperature Measurement
The circuits can be used in ratiometric applications or with
an external reference. The high impedance analog inputs
and the ability to operate with reduced spans (to 1V full
scale) allow direct connection to sensors and transducers
in many applications, eliminating the need for gain stages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
MICROWIRE is a registered trademark of National Semiconductor Corporation.
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TYPICAL APPLICATI
10µW, SO-8 Package, 8-Bit A/D Converter
Samples at 200Hz and Runs Off a 3V Battery
ANALOG INPUT
0V TO 3V RANGE
1 CS/
VCC
SHDN
2
+IN
CLK
LTC1096L
3
–IN
DOUT
4
GND
VREF
3V
MPU
8
SERIAL DATA LINK
(MICROWIRE AND
SPI COMPATIBLE)
7
6
5
1000
SUPPLY CURRENT, ICC (µA)
1µF
Supply Current vs Sample Rate
100
10
SERIAL DATA LINK
1096/8 TA01
1
0.1
1
10
SAMPLE FREQUENCY (kHz)
100
1096/8 TA02
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LTC1096L/LTC1098L
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ABSOLUTE
RATI GS
(Notes 1 and 2)
Operating Temperature
LTC1096LAC/LTC1098LAC .................... 0°C to 70°C
LTC1096LAI/LTC1098LAI .................. – 40°C to 85°C
LTC1096LC/LTC1098LC......................... 0°C to 70°C
LTC1096LI/LTC1098LI ....................... – 40°C to 85°C
Storage Temperature Range ................. – 65°c to 150°C
Lead Temperature (Soldering, 10 sec.)................ 300°C
Supply Voltage (VCC) to GND ................................... 12V
Voltage
Analog and Reference ................ –0.3V to VCC + 0.3V
Digital Inputs......................................... –0.3V to 12V
Digital Outputs ........................... –0.3V to VCC + 0.3V
Power Dissipation.............................................. 500mW
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PACKAGE/ORDER I FOR ATIO
(Note 3)
ORDER PART
NUMBER
ORDER PART
NUMBER
TOP VIEW
CS/
1
SHDN
+IN 2
8 VCC
7 CLK
–IN 3
6 DOUT
GND 4
5 VREF
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 175°C/W
TOP VIEW
LTC1096LACS8
LTC1096LAIS8
LTC1096LCS8
LTC1096LIS8
CS/
1
SHDN
CH0 2
S8 PART MARKING
096LIA
1096LA
1096LI
1096L
8 VCC(VREF)
7 CLK
CH1 3
6 DOUT
GND 4
5 DIN
LTC1098LACS8
LTC1098LAIS8
LTC1098LCS8
LTC1098LIS8
S8 PART MARKING
098LIA
1098LA
1098LI
1098L
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 175°C/W
Consult factory for Military grade parts.
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RECO
E DED OPERATI G CO DITIO S
SYMBOL
PARAMETER
VCC
Supply Voltage
2.65
4.0
V
fCLK
Clock Frequency
VCC = 2.65V
25
250
kHz
tCYC
Total Cycle Time
LTC1096L, fCLK = 250kHz
LTC1098L, fCLK = 250kHz
58
58
µs
µs
thDI
Hold Time, DIN After CLK↑
VCC = 2.65V
450
ns
tsuCS
Setup Time CS↓ Before First CLK↑ (See Operating Sequence)
VCC = 2.65V, LTC1096L
VCC = 2.65V, LTC1098L
1
1
µs
µs
tWAKEUP
Wakeup Time CS↓ Before First CLK↓ After First CLK↑
(See Figure 1, LTC1096L Operating Sequence)
VCC = 2.65V, LTC1096L
10
µs
Wakeup Time CS↓ Before MSBF Bit CLK↓
(See Figure 2, LTC1098L Operating Sequence)
VCC = 2.65V, LTC1098L
10
µs
tsuDI
Setup Time, DIN Stable Before CLK↑
VCC = 2.65V
1
µs
tWHCLK
CLK High Time
VCC = 2.65V
1.6
µs
tWLCLK
CLK Low Time
VCC = 2.65V
1.6
µs
tWHCS
CS High Time Between Data Transfer Cycles
VCC = 2.65V
2
µs
tWLCS
CS Low Time During Data Transfer
LTC1096L, fCLK = 250kHz
LTC1098L, fCLK = 250kHz
56
56
µs
µs
2
CONDITIONS
MIN
TYP
MAX
UNITS
LTC1096L/LTC1098L
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CO VERTER A D ULTIPLEXER CHARACTERISTICS
VCC = 2.65V, VREF = 2.5V, fCLK = 250kHz, unless otherwise noted.
PARAMETER
LTC1096LA/LTC1098LA
MIN
TYP
MAX
CONDITIONS
Resolution (No Missing Code)
●
8
LTC1096L/LTC1098L
MIN
TYP
MAX
8
UNITS
Bits
●
±0.5
±1
Linearity Error
●
±0.5
±1
LSB
Full Scale Error
●
±0.5
±1
LSB
±1
±1.5
LSB
Offset Error
(Note 4)
LSB
Total Unadjusted Error (Note 5)
VREF = 2.5V
Analog Input Range
(Note 6)
– 0.05V to VCC + 0.05V
V
REF Input Range (Note 6)
2.65 ≤ VCC ≤ 4.0V
– 0.05V to VCC + 0.05V
V
Analog Input Leakage Current
(Note 7)
●
●
±1
±1
µA
MAX
UNITS
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DIGITAL A D DC ELECTRICAL CHARACTERISTICS
VCC = 2.65V, VREF = 2.5V, fCLK = 250kHz, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
VIH
High Level Input Voltage
VCC = 3.6V
●
VIL
Low Level Input Voltage
VCC = 2.65V
●
0.45
V
IIH
High Level Input Current
VIN = VCC
●
2.5
µA
IIL
Low Level Input Current
VIN = 0V
●
– 2.5
µA
VOH
High Level Output Voltage
VCC = 2.65V, IO = 10µA
IO = 360µA
●
●
VOL
Low Level Output Voltage
VCC = 2.65V, IO = 400µA
●
0.3
V
IOZ
Hi-Z Output Leakage
CS =High
●
±3
µA
ISOURCE
Output Source Current
VOUT = 0V
ISINK
Output Sink Current
VOUT = VCC
IREF
Reference Current
CS = VCC
tCYC ≥ 200µs, fCLK ≤ 50kHz
tCYC = 58µs, fCLK = 250kHz
●
●
●
0.001 2.5
3.500 7.5
35.00 50.0
µA
µA
µA
ICC
Supply Current
CS = VCC
●
0.001
± 3
µA
1.9
2.4
2.1
V
2.64
2.50
V
V
– 10
mA
15
mA
LTC1096L,
tCYC ≥ 200µs, fCLK ≤ 50kHz
tCYC = 58µs, fCLK = 250kHz
●
●
40
120
80
180
µA
µA
LTC1098L,
tCYC ≥ 200µs, fCLK ≤ 50kHz
tCYC = 58µs, fCLK = 250kHz
●
●
44
155
88
230
µA
µA
3
LTC1096L/LTC1098L
AC CHARACTERISTICS
VCC = 2.65V, VREF = 2.5V, fCLK = 250kHz, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
tSMPL
Analog Input Sample Time
See Operating Sequences
MIN
fSMPL(MAX)
Maximum Sampling Frequency
MAX
tCONV
Conversion Time
See Operating Sequences
tdDO
Delay Time, CLK↓ to DOUT Data Valid
See Test Circuits
●
500
1000
ns
tdis
Delay Time, CS↑ to DOUT Hi-Z
See Test Circuits
●
220
800
ns
ten
Delay Time, CLK↓ to DOUT Enable
See Test Circuits
●
160
480
ns
thDO
Time Output Data Remains Valid After CLK↓
CLOAD = 100pF
tf
DOUT Fall Time
See Test Circuits
tr
DOUT Rise Time
See Test Circuits
CIN
Input Capacitance
Analog Inputs
1.5
●
On Channel
Off Channel
UNITS
CLK Cycles
16.5
kHz
8
CLK Cycles
400
Digital Input
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: All voltage values are with respect to GND.
Note 3: This device is specified at 2.65V. Consult factory for 5V specified
devices.
Note 4: Linearity error is specified between the actual end points of the
A/D transfer curve.
Note 5: Total unadjusted error includes offset, full scale, linearity,
multiplexer and hold step errors.
TYP
ns
●
70
250
ns
●
50
200
ns
25
5
pF
pF
5
pF
Note 6: Two on-chip diodes are tied to each reference and analog input
which will conduct for reference or analog input voltages one diode drop
below GND or one diode drop above VCC. This spec allows 50mV forward
bias of either diode for 2.65V ≤ VCC ≤ 3.6V. This means that as long as the
reference or analog input does not exceed the supply voltage by more than
50mV, the output code will be correct. To achieve an absolute 0V to 3V
input voltage range will therefore require a minimum supply voltage of
2.950V over initial tolerance, temperature variations and loading.
Note 7: Channel leakage current is measured after the channel selection.
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PI FU CTIO S
LTC1096L
CS/SHDN (Pin 1): Chip Select Input. A logic low on this
input enables the LTC1096L. A logic high on this input
disables the LTC1096L and disconnects the power to the
LTC1096L.
IN+ (Pin 2): Analog Input. This input must be free of noise
with respect to GND.
DOUT (Pin 6): Digital Data Output. The A/D conversion
result is shifted out of this output.
CLK (Pin 7): Shift Clock. This clock synchronizes the serial
data transfer.
VCC (Pin 8): Power Supply Voltage. This pin provides
power to the A/D converter. It must be free of noise and
ripple by bypassing directly to the analog ground plane.
IN– (Pin 3): Analog Input. This input must be free of noise
with respect to GND.
LTC1098L
GND (Pin 4): Analog Ground. GND should be tied directly
to an analog ground plane.
CS/SHDN (Pin 1): Chip Select Input. A logic low on this
input enables the LTC1098L. A logic high on this input
disables the LTC1098L and disconnects the power to the
LTC1098L.
VREF (Pin 5): Reference Input. The reference input defines
the span of the A/D converter and must be kept free of
noise with respect to GND.
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CHO (Pin 2): Analog Input. This input must be free of noise
with respect to GND.
LTC1096L/LTC1098L
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CH1 (Pin 3): Analog Input. This input must be free of noise
with respect to GND.
DOUT (Pin 6): Digital Data Output. The A/D conversion
result is shifted out of this output.
GND (Pin 4): Analog Ground. GND should be tied directly
to an analog ground plane.
CLK (Pin 7): Shift Clock. This clock synchronizes the serial
data transfer.
DIN (Pin 5): Digital Data Input. The multiplexer address is
shifted into this pin.
VCC (VREF) (Pin 8): Power Supply Voltage. This pin provides power and defines the span of the A/D converter. It
must be free of noise and ripple by bypassing directly to
the analog ground plane
TEST CIRCUITS
Load Circuit for tdDO, tr and tf
Voltage Waveforms for DOUT Rise and Fall Times, tr, tf
1.4V
3k
VOH
DOUT
DOUT
VOL
TEST POINT
100pF
tr
tf
LTC1096/98 • TC02
LTC1096/98 • TC01
Load Circuit for tdis and ten
Voltage Waveforms for tdis
VIH
CS
TEST POINT
VCC tdis WAVEFORM 2, t en
3k
DOUT
90%
tdis
tdis WAVEFORM 1
100pF
DOUT
WAVEFORM 1
(SEE NOTE 1)
LTC1096/98 • TC03
DOUT
WAVEFORM 2
(SEE NOTE 2)
10%
NOTE 1: WAVEFORM 1 IS FOR AN OUTPUT WITH INTERNAL CONDITIONS SUCH
THAT THE OUTPUT IS HIGH UNLESS DISABLED BY THE OUTPUT CONTROL.
NOTE 2: WAVEFORM 2 IS FOR AN OUTPUT WITH INTERNAL CONDITIONS SUCH
THAT THE OUTPUT IS LOW UNLESS DISABLED BY THE OUTPUT CONTROL.
LTC1096/98 • TC04
Voltage Waveforms for DOUT Delay Time, tdDO
CLK
VIL
tdDO
VOH
DOUT
VOL
LTC1096/98 • TC05
5
LTC1096L/LTC1098L
TEST CIRCUITS
Voltage Waveforms for ten
LTC1096L
CS
t WAKEUP
1
CLK
B7
DOUT
VOL
t en
LTC1096/98 • TC06
LTC1098L
CS
START
DIN
1
CLK
2
3
4
5
B7
DOUT
VOL
t en
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APPLICATI
LTC1096/98 • TC07
S I FOR ATIO
INPUT DATA WORD
Start Bit
The LTC1096L requires no DIN word. It is permanently
configured to have a single differential input. The conversion result, in which the output on the DOUT line is
presented in MSB-first sequence followed by LSB sequence, provides easy interface to MSB- or LSB-first
serial ports.
The first “logical one” clocked into the DIN input after CS
goes low is the start bit. The start bit initiates the data
transfer. The LTC1098L will ignore all leading zeroes
which precede this logical one. After the start bit is
received, the remaining bits of the input word will be
clocked in. Further inputs on the DIN pin are then ignored
until the next CS cycle.
The LTC1098L latches data into the DIN input on the rising
edge of the clock. The input data words are defined as
follows:
SGL/
START
DIFF
ODD/
MSBF
SIGN
MUX MSB-FIRST/
ADDRESS LSB-FIRST
LTC1096/9 • AI01
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Multiplexer (MUX) Address
The bits of the input word following the START bit assign
the MUX configuration for the requested conversion. For
a given channel selection, the converter will measure the
voltage between the two channels indicated by the “+” and
“–” signs in the selected row of the following tables. In
LTC1096L/LTC1098L
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APPLICATI
S I FOR ATIO
single-ended mode, all input channels are measured with
respect to GND.
not use wire wrapping techniques to breadboard and
evaluate the device. To achieve the optimum performance
use a printed circuit board. The GND pin (Pin 4) should be
tied directly to the ground plane with minimum lead
length.
LTC1098L Channel Selection
MUX ADDRESS
CHANNEL #
ODD/SIGN CH0
SGL/DIFF
CH1 GND
0
1
–
+
1
1
–
+
0
0
–
+
1
0
+
–
Bypassing
For good performance, the LTC1096L/LTC1098L VCC and
VREF pins must be free of noise and ripple. Any changes in
the VCC and VREF voltage with respect to ground during the
conversion cycle can induce errors or noise in the output
code. Bypass the VCC and VREF pins directly to the analog
ground plane with a minimum 0.1µF capacitor and with
leads as short as possible. The LTC1098L combines VCC
and VREF into one pin, VCC(VREF), which can be bypassed
by a 0.1µF capacitor.
LTC1096/8 • AI02
MSB-First/LSB-First (MSBF)
The output data of the LTC1098L is programmed for
MSB-first or LSB-first sequence using the MSBF bit.
When the MSBF bit is a logical one, data will appear on
the DOUT line in MSB-first format. Logical zeroes will be
filled in indefinitely following the last data bit. When the
MSBF bit is a logical zero, LSB-first data will follow the
normal MSB-first data on the DOUT line (see Figures 1
and 2).
Analog Inputs
Because of the capacitive redistribution A/D conversion
techniques used, the analog inputs of the LTC1096L/
LTC1098L have capacitive switching input current spikes.
These current spikes settle quickly and do not cause a
problem. But if large source resistances are used or if slow
settling op amps drive the inputs, take care to ensure the
transients caused by the current spikes settle completely
before the conversion begins.
ANALOG CONSIDERATIONS
Grounding
The LTC1096L/LTC1098L should be used with an analog
ground plane and single point grounding techniques. Do
t CYC
CS
POWER
DOWN
CLK
tsuCS
tWAKEUP
DOUT
Hi-Z
NULL
BIT
B7
B6
B5
B4
B3
B2
B1
B0
B1
B2
tCONV
B3
B4
B5
B6
B7
Hi-Z
FILLED
WITH
ZEROES
LTC1096/98 F01
Figure 1. LTC1096L Operating Sequence
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LTC1096L/LTC1098L
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APPLICATI
S I FOR ATIO
MSB-FIRST DATA (MSBF = 0)
tCYC
CS
POWER
DOWN
tWAKEUP
CLK
tsuCS
ODD/
SIGN
START
DIN
DON'T CARE
SGL/
DIFF
DOUT
MSBF
NULL
BIT B7
Hi-Z
B6
B5
tSMPL
B4
B3
B2
B1
B0
B1
B2
B3
B4
B5
B6
Hi-Z
B7
FILLED
WITH
ZEROES
tCONV
LTC1096/98 F02
Figure 2. LTC1098L Operating Sequence Example: Differential Inputs (CH+, CH–)
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PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
7
8
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
0.014 – 0.019
(0.355 – 0.483)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
0.004 – 0.010
(0.101 – 0.254)
6
5
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
0.050
(1.270)
BSC
1
2
3
4
SO8 0695
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
RELATED PARTS
PART NUMBER
DESCRIPTION
LTC1096/LTC1098 8-Pin SO, Micropower 8-Bit ADC
COMMENTS
Low Power, Small Size, Low Cost
LTC1196/LTC1198 8-Pin SO, 1Msps 8-Bit ADC
Low Power, Small Size, Low Cost
LTC1285/LTC1288 8-Pin SO, 3V Micropower 12-Bit ADC
12-Bit ADC in SO-8
LTC1289
Multiplexed 3V 12-Bit ADC
8-Channel 12-Bit Serial I/O
LTC1584L
Multiplexed 3V 12-Bit ADC
4-Channel 12-Bit Serial I/O, Micropower
8
Linear Technology Corporation
LT/GP 1295 5K REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1995
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