LINER LTC2637

LTC2637
Octal 12-/10-/8-Bit I2C VOUT
DACs with 10ppm/°C Reference
Description
Features
Integrated Precision Reference:
2.5V Full-Scale 10ppm/°C (LTC2637-L)
4.096V Full-Scale 10ppm/°C (LTC2637-H)
n Maximum INL Error: 2.5LSB (LTC2637-12)
n Low Noise: 0.75mV
P-P 0.1Hz to 200KHz
n Guaranteed Monotonic Over –40°C to 125°C
Temperature Range
n Selectable Internal or External Reference
n 2.7V to 5.5V Supply Range (LTC2637-L)
n Ultralow Crosstalk Between DACs (<3nV•s)
n Low Power: 100µA per DAC at 3V (LTC2637-L)
n Power-On-Reset to Zero-Scale/Mid-Scale
n Double-Buffered Data Latches
n Tiny 14-Lead 4mm × 3mm DFN and 16-Lead MSOP
Packages
The LTC®2637 is a family of octal 12-, 10-, and 8-bit
voltage-output DACs with an integrated, high-accuracy,
low-drift 10ppm/°C reference in 14-lead DFN and 16-lead
MSOP packages. It has a rail-to-rail output buffer and is
guaranteed monotonic. The LTC2637-L has a full-scale
output of 2.5V, and operates from a single 2.7V to 5.5V
supply. The LTC2637-H has a full-scale output of 4.096V,
and operates from a 4.5V to 5.5V supply. Each DAC can
also operate with an external reference, which sets the DAC
full-scale output to the external reference voltage.
n
These DACs communicate via a 2-wire I2C-compatible
serial interface. The LTC2637 operates in both the standard
mode (clock rate of 100kHz) and the fast mode (clock rate
of 400kHz). The LTC2637 incorporates a power-on reset
circuit. Options are available for reset to zero-scale or
reset to mid-scale in internal reference mode, or reset to
mid-scale in external reference mode after power-up.
Applications
n
n
n
n
n
Mobile Communications
Process Control and Industrial Automation
Automatic Test Equipment
Portable Equipment
Automotive
Optical Networking
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 5396245, 5859606, 6891433, 6937178, 7414561.
Block Diagram
SWITCH
INTERNAL REFERENCE
REF
Integral Nonlinearity (LTC2637-LZ12)
VREF
GND
2
VCC = 3V
INTERNAL REF.
REGISTER
REGISTER
DAC A
REGISTER
VOUTA
REGISTER
VCC
DAC H
VREF
REGISTER
REGISTER
DAC B
REGISTER
VOUTB
REGISTER
VREF
DAC G
REGISTER
REGISTER
REGISTER
REGISTER
DAC D
REGISTER
VOUTD
REGISTER
VREF
REGISTER
DAC C
REGISTER
VOUTC
(CA2)
DAC F
0
–1
VOUTF
VREF
–2
0
1024
2048
CODE
3072
4095
2637 TA01
DAC E
VOUTE
POWER-ON RESET
CAO
(CA1)
VOUTG
VREF
VREF
1
VOUTH
INL (LSB)
n
DECODE
I2C
ADDRESS
DECODE
SCL
SDA
I2C INTERFACE
( ) MSOP PACKAGE ONLY
2637 BD
2637fa
LTC2637
Absolute Maximum Ratings
(Notes 1, 2)
Supply Voltage (VCC).................................... –0.3V to 6V
SCL, SDA...................................................... –0.3V to 6V
VOUTA - VOUTH,
CA0, CA1, CA2....................–0.3V to Min(VCC + 0.3V, 6V)
REF....................................–0.3V to Min(VCC + 0.3V, 6V)
Operating Temperature Range
LTC2637C................................................. 0°C to 70°C
LTC2637I..............................................–40°C to 85°C
LTC2637H (Note 3)............................. –40°C to 125°C
Maximum Junction Temperature........................... 150°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
MS Package....................................................... 300°C
Pin Configuration
TOP VIEW
VCC
1
14 GND
VOUTA
2
VOUTB
3
13 VOUTH
VOUTC
4
VOUTD
5
CA0
6
SCL
7
15
12 VOUTG
11 VOUTF
10 VOUTE
9 REF
8 SDA
DE PACKAGE
14-LEAD (4mm s 3mm) PLASTIC DFN
TOP VIEW
VCC 1
VOUTA 2
VOUTB 3
VOUTC 4
VOUTD 5
CA2 6
CA0 7
SCL 8
16
15
14
13
12
11
10
9
GND
VOUTH
VOUTG
VOUTF
VOUTE
REF
CA1
SDA
MS PACKAGE
16-LEAD (4mm s 5mm) PLASTIC MSOP
TJMAX = 150°C, θJA = 110°C/W
TJMAX = 150°C, θJA = 37°C/W
EXPOSED PAD (PIN 15) IS GND, MUST BE SOLDERED TO PCB
2637fa
LTC2637
Order Information
LTC2637 C
DE
–L
Z
12
#TR
PBF
LEAD FREE DESIGNATOR
TAPE AND REEL
TR = 2500-Piece Tape and Reel
RESOLUTION
12 = 12-Bit
10 = 10-Bit
8 = 8-Bit
POWER-ON RESET
MI = Reset to Mid-Scale in Internal Reference Mode
MX = Reset to Mid-Scale in External Reference Mode
Z = Reset to Zero-Scale in Internal Reference Mode
FULL-SCALE VOLTAGE, INTERNAL REFERENCE MODE
L = 2.5V
H = 4.096V
PACKAGE TYPE
DE = 14-Lead DFN
MS = 16-Lead MSOP
TEMPERATURE GRADE
C = Commercial Temperature Range (0°C to 70°C)
I = Industrial Temperature Range (–40°C to 85°C)
H = Automotive Temperature Range (–40°C to 125°C)
PRODUCT PART NUMBER
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
2637fa
LTC2637
Product Selection Guide
PART MARKING*
POWER-ON
RESET TO CODE
POWER-ON
REFERENCE
MODE
RESOLUTION
VCC
PART NUMBER
DFN
MSOP
VFS WITH INTERNAL
REFERENCE
MAXIMUM
INL
LTC2637-LMI12
7LMI2
7LMI12
2.5V • (4095/4096)
Mid-Scale
Internal
12-Bit
2.7V to 5.5V
LTC2637-LMI10
7LMI1
7LMI10
2.5V • (1023/1024)
Mid-Scale
Internal
10-Bit
2.7V to 5.5V
±1LSB
LTC2637-LMI8
7LMI8
37LMI8
2.5V • (255/256)
Mid-Scale
Internal
8-Bit
2.7V to 5.5V
±0.5LSB
LTC2637-LMX12
7LMX2
7LMX12 2.5V • (4095/4096)
Mid-Scale
External
12-Bit
2.7V to 5.5V
±2.5LSB
LTC2637-LMX10
7LMX1
7LMX10 2.5V • (1023/1024)
Mid-Scale
External
10-Bit
2.7V to 5.5V
±1LSB
LTC2637-LMX8
7LMX8
37LMX8 2.5V • (255/256)
Mid-Scale
External
8-Bit
2.7V to 5.5V
±0.5LSB
LTC2637-LZ12
7LZ12
37LZ12
2.5V • (4095/4096)
Zero-Scale
Internal
12-Bit
2.7V to 5.5V
±2.5LSB
LTC2637-LZ10
7LZ10
37LZ10
2.5V • (1023/1024)
Zero-Scale
Internal
10-Bit
2.7V to 5.5V
±1LSB
LTC2637-LZ8
37LZ8
637LZ8
2.5V • (255/256)
Zero-Scale
Internal
8-Bit
2.7V to 5.5V
±0.5LSB
LTC2637-HMI12
7HMI2
7HMI12
4.096V • (4095/4096)
Mid-Scale
Internal
12-Bit
4.5V to 5.5V
±2.5LSB
LTC2637-HMI10
7HMI1
7HMI10
4.096V • (1023/1024)
Mid-Scale
Internal
10-Bit
4.5V to 5.5V
±1LSB
4.096V • (255/256)
±2.5LSB
LTC2637-HMI8
7HMI8
37HMI8
Mid-Scale
Internal
8-Bit
4.5V to 5.5V
±0.5LSB
LTC2637-HMX12
7HMX2
7HMX12 4.096V • (4095/4096)
Mid-Scale
External
12-Bit
4.5V to 5.5V
±2.5LSB
LTC2637-HMX10
7HMX1
7HMX10 4.096V • (1023/1024)
Mid-Scale
External
10-Bit
4.5V to 5.5V
±1LSB
LTC2637-HMX8
7HMX8
37HMX8 4.096V • (255/256)
Mid-Scale
External
8-Bit
4.5V to 5.5V
±0.5LSB
LTC2637-HZ12
7HZ12
37HZ12
4.096V • (4095/4096)
Zero-Scale
Internal
12-Bit
4.5V to 5.5V
±2.5LSB
LTC2637-HZ10
7HZ10
37HZ10
4.096V • (1023/1024)
Zero-Scale
Internal
10-Bit
4.5V to 5.5V
±1LSB
LTC2637-HZ8
37HZ8
637HZ8
4.096V • (255/256)
Zero-Scale
Internal
8-Bit
4.5V to 5.5V
±0.5LSB
*Above options are available in a 14-lead DFN package (LTC2637xDE) or 16-lead MSOP package (LTC2637xMS).
2637fa
LTC2637
Electrical
Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 2.7V to 5.5V, VOUT unloaded unless otherwise specified.
LTC2637-LMI12/ LTC2637-LMI10/ LTC2637-LMI8/ LTC2637-LMX12/ LTC2637-LMX10/ LTC2637-LMX8/ LTC2637-LZ12/
LTC2637-LZ10/ LTC2637-LZ8 (VFS = 2.5V)
LTC2637-8
SYMBOL PARAMETER
CONDITIONS
MIN TYP
Resolution
DNL
l
8
8
Monotonicity
VCC = 3V, Internal Reference (Note 4)
l
Differential Nonlinearity
VCC = 3V, Internal Reference (Note 4)
l
LTC2637-10
LTC2637-12
MAX MIN TYP
MAX MIN TYP
10
12
10
MAX
Bits
12
±0.5
UNITS
Bits
±0.5
±1
LSB
INL
Integral Nonlinearity
VCC = 3V, Internal Reference (Note 4)
l
±0.05
±0.5
±0.2
±1
±1
±2.5
LSB
ZSE
Zero-Scale Error
VCC = 3V, Internal Reference, Code = 0
l
0.5
5
0.5
5
0.5
5
mV
VOS
Offset Error
VCC = 3V, Internal Reference (Note 5)
l
±0.5
±5
±0.5
±5
±0.5
±5
mV
VOSTC
VOS Temperature
Coefficient
VCC =3V, Internal Reference
GE
Gain Error
VCC = 3V, Internal Reference
GETC
Gain Temperature
Coefficient
VCC = 3V, Internal Reference (Note 10)
C-Grade
I-Grade
H-Grade
Load Regulation
Internal Reference, Mid-Scale,
VCC = 3V±10%,
–5mA ≤ IOUT ≤ 5mA
VCC = 5V±10%, (Note 15)
–10mA ≤ IOUT ≤ 10mA
ROUT
DC Output Impedance
Internal Reference, Mid-Scale,
VCC = 3V±10%,
–5mA ≤ IOUT ≤ 5mA
VCC = 5V±10%, (Note 15)
–10mA ≤ IOUT ≤ 10mA
±10
l
±0.2
±10
±0.8
±0.2
10
10
10
±10
±0.8
µV/°C
±0.2
10
10
10
±0.8
10
10
10
%FSR
ppm/°C
ppm/°C
ppm/°C
l
0.009 0.016
0.035 0.064
0.14 0.256 LSB/mA
l
0.009 0.016
0.035 0.064
0.14 0.256 LSB/mA
l
0.09
0.156
0.09
0.156
0.09 0.156
Ω
l
0.09
0.156
0.09
0.156
0.09 0.156
Ω
SYMBOL
PARAMETER
CONDITIONS
VOUT
DAC Output Span
External Reference
Internal Reference
MIN
PSR
Power Supply Rejection
VCC = 3V±10% or 5V±10%
ISC
Short Circuit Output Current (Note 6)
Sinking
Sourcing
VFS = VCC = 5.5V
Zero-Scale; VOUT shorted to VCC
Full-Scale; VOUT shorted to GND
l
l
TYP
MAX
UNITS
0 to VREF
0 to 2.5
V
V
–80
dB
27
–28
48
–48
mA
mA
5.5
V
Power Supply
VCC
Positive Supply Voltage
For Specified Performance
l
2.7
ICC
Supply Current (Note 7)
VCC = 3V, VREF =2.5V, External Reference
VCC = 3V, Internal Reference
VCC = 5V, VREF =2.5V, External Reference
VCC = 5V, Internal Reference
l
l
l
l
0.8
0.9
0.9
1
1.1
1.3
1.3
1.5
mA
mA
mA
mA
ISD
Supply Current in Power-Down Mode
(Note 7)
VCC = 5V, C-Grade, I-Grade
VCC = 5V, H-Grade
l
l
1
1
20
30
µA
µA
2637fa
LTC2637
Electrical
Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 2.7V to 5.5V, VOUT unloaded unless otherwise specified.
LTC2637-LMI12/ LTC2637-LMI10/ LTC2637-LMI8/ LTC2637-LMX12/ LTC2637-LMX10/ LTC2637-LMX8/ LTC2637-LZ12/
LTC2637-LZ10/ LTC2637-LZ8 (VFS = 2.5V)
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VCC
V
200
kΩ
Reference Input
Input Voltage Range
l
1
Resistance
l
120
Capacitance
IREF
Reference Current, Power-Down Mode
160
12
DAC Powered Down
l
pF
0.005
1.5
µA
1.25
1.26
V
Reference Output
Output Voltage
l
1.24
Reference Temperature Coefficient
±10
ppm/°C
Output Impedance
0.5
kΩ
Capacitive Load Driving
10
µF
2.5
mA
Short Circuit Current
VCC = 5.5V; REF Shorted to GND
Digital I/O
VIL
Low Level Input Voltage (SDA and SCL)
(Note 14)
l
–0.5
VIH
High Level Input Voltage (SDA and SCL)
(Note 11)
l
0.7VCC
0.3VCC
V
VIL(CAn)
Low Level Input Voltage on CAn
(n = 0, 1, 2)
See Test Circuit 1
l
VIH(CAn)
High Level Input Voltage on CAn
(n = 0, 1, 2)
See Test Circuit 1
l
RINH
Resistance from CAn (n=0, 1,2)
to VCC to Set CAn = VCC
See Test Circuit 2
l
10
kΩ
RINL
Resistance from CAn (n=0, 1,2)
to GND to Set CAn = GND
See Test Circuit 2
l
10
kΩ
RINF
Resistance from CAn (n=0, 1,2)
to VCC or GND to Set CAn = Float
See Test Circuit 2
l
VOL
Low Level Output Voltage
Sink Current = 3mA
l
0
0.4
V
tOF
Output Fall Time
VO = VIH(MIN) to VO = VIL(MAX),
CB = 10pF to 400pF (Note 12)
l
20 + 0.1CB
250
ns
tSP
Pulse Width of Spikes Suppressed
by Input Filter
l
0
50
ns
IIN
Input Leakage
0.1VCC ≤ VIN ≤ 0.9VCC
l
±1
µA
CIN
I/O Pin Capacitance
(Note 8)
l
10
pF
CB
Capacitive Load for Each Bus Line
l
400
pF
CCAn
External Capacitive Load on Address
Pin CAn (n=0, 1,2)
l
10
pF
V
0.15VCC
0.85VCC
V
V
2
MΩ
2637fa
LTC2637
Electrical
Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 2.7V to 5.5V, VOUT unloaded unless otherwise specified.
LTC2637-LMI12/ LTC2637-LMI10/ LTC2637-LMI8/ LTC2637-LMX12/ LTC2637-LMX10/ LTC2637-LMX8/ LTC2637-LZ12/
LTC2637-LZ10/ LTC2637-LZ8 (VFS = 2.5V)
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
AC Performance
tS
Settling Time
VCC = 3V (Note 9)
±0.39% (±1LSB at 8 Bits)
±0.098% (±1LSB at 10 Bits)
±0.024% (±1LSB at 12 Bits)
Voltage Output Slew Rate
Capacitive Load Driving
Glitch Impulse
en
At Mid-Scale Transition
3.5
4.1
4.5
µs
µs
µs
1.0
V/µs
500
pF
2.1
nV•s
DAC-to-DAC Crosstalk
1 DAC held at FS, 1 DAC Switched 0 to FS
2.6
nV•s
Multiplying Bandwidth
External Reference
320
kHz
Output Voltage Noise Density
At f = 1kHz, External Reference
At f = 10kHz, External Reference
At f = 1kHz, Internal Reference
At f = 10kHz, Internal Reference
180
160
200
180
nV/√Hz
nV/√Hz
nV/√Hz
nV/√Hz
Output Voltage Noise
0.1Hz to 10Hz, External Reference
0.1Hz to 10Hz, Internal Reference
0.1Hz to 200kHz, External Reference
0.1Hz to 200kHz, Internal Reference
35
40
680
730
µVP-P
µVP-P
µVP-P
µVP-P
Timing
Characteristics
The l denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at TA = 25°C. VCC = 2.7V to 5.5V. (See Figure 1) (Note 13)
LTC2637-LMI12/ LTC2637-LMI10/ LTC2637-LMI8/ LTC2637-LMX12/ LTC2637-LMX10/ LTC2637-LMX8/ LTC2637-LZ12/
LTC2637-LZ10/ LTC2637-LZ8 (VFS = 2.5V)
SYMBOL PARAMETER
CONDITIONS
MIN
0
TYP
MAX
UNITS
400
kHz
fSCL
SCL Clock Frequency
l
tHD(STA)
Hold Time (Repeated) Start Condition
l
0.6
µs
tLOW
Low Period of the SCL Clock Pin
l
1.3
µs
tHIGH
High Period of the SCL Clock Pin
l
0.6
µs
tSU(STA)
Set-Up Time for a Repeated Start Condition
l
0.6
µs
tHD(DAT)
Data Hold Time
l
0
tSU(DAT)
Data Set-Up Time
l
100
tr
Rise Time of Both SDA and SCL Signals
(Note 12)
l
20 + 0.1CB
300
ns
tf
Fall Time of Both SDA and SCL Signals
(Note 12)
l
20 + 0.1CB
300
ns
tSU(STO)
Set-Up Time for Stop Condition
l
0.6
µs
tBUF
Bus Free Time Between a Stop and Start Condition
l
1.3
µs
0.9
µs
ns
2637fa
LTC2637
Electrical
Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 4.5V to 5.5V, VOUT unloaded unless otherwise specified.
LTC2637-HMI12/ LTC2637-HMI10/ LTC2637-HMI8/ LTC2637-HMX12/ LTC2637-HMX10/ LTC2637-HMX8/ LTC2637-HZ12/
LTC2637-HZ10/ LTC2637-HZ8 (VFS =4.096V)
LTC2637-8
SYMBOL PARAMETER
CONDITIONS
MIN
Resolution
TYP
LTC2637-10
MAX MIN
TYP
LTC2637-12
MAX MIN TYP
MAX
8
10
12
Bits
8
10
12
Bits
Monotonicity
VCC = 5V, Internal Reference (Note 4)
l
DNL
Differential
Nonlinearity
VCC = 5V, Internal Reference (Note 4)
l
INL
Integral Nonlinearity
VCC = 5V, Internal Reference (Note 4)
l
±0.05
±0.5
±0.2
±1
ZSE
Zero-Scale Error
VCC = 5V, Internal Reference, Code = 0
l
0.5
5
0.5
5
VOS
Offset Error
VCC = 5V, Internal Reference (Note 5)
l
±0.5
±5
±0.5
±5
±0.5
VOSTC
VOS Temperature
Coefficient
VCC = 5V, Internal Reference
±0.5
±0.5
±10
±0.8
LSB
±1
±2.5
LSB
0.5
5
mV
±5
mV
±10
±0.2
Gain Error
VCC = 5V, Internal Reference
Gain Temperature
Coefficient
VCC = 5V, Internal Reference (Note 10)
C-Grade
I-Grade
H-Grade
Load
Regulation
VCC = 5V±10%, (Note 15)
Internal Reference, Mid-Scale,
–10mA ≤ IOUT ≤ 10mA
l
0.006
0.01
0.022
0.04
0.09
DC Output
Impedance
VCC = 5V±10%, (Note 15)
Internal Reference, Mid-Scale,
–10mA ≤ IOUT ≤ 10mA
l
0.09
0.156
0.09
0.156
0.09 0.156
10
10
10
SYMBOL
PARAMETER
CONDITIONS
VOUT
DAC Output Span
External Reference
Internal Reference
±0.8
±0.2
µV/°C
GE
l
±0.2
±10
±1
GETC
ROUT
UNITS
l
10
10
10
10
10
10
MIN
PSR
Power Supply Rejection
VCC = 5V±10%
ISC
Short Circuit Output Current (Note 6)
Sinking
Sourcing
VFS = VCC = 5.5V
Zero-Scale; VOUT Shorted to VCC
Full-Scale; VOUT Shorted to GND
l
l
±0.8
TYP
%FSR
ppm/°C
ppm/°C
ppm/°C
0.16 LSB/mA
MAX
Ω
UNITS
0 to VREF
0 to 4.096
V
V
–80
dB
27
–28
48
–48
mA
mA
5.5
V
Power Supply
VCC
Positive Supply Voltage
For Specified Performance
l
4.5
ICC
Supply Current (Note 7)
VCC = 5V, VREF = 4.096V, External Reference
VCC = 5V, Internal Reference
l
l
1.0
1.1
1.3
1.5
mA
mA
ISD
Supply Current in Power-Down Mode
(Note 7)
VCC = 5V, C-Grade, I-Grade
VCC = 5V, H-Grade
l
l
1
1
20
30
µA
µA
VCC
V
200
kΩ
Reference Input
Input Voltage Range
l
1
Resistance
l
120
Capacitance
IREF
Reference Current, Power-Down Mode
160
12
DAC Powered Down
l
pF
0.005
1.5
µA
2.048
2.064
V
Reference Output
Output Voltage
Reference Temperature Coefficient
l
2.032
±10
ppm/°C
2637fa
LTC2637
Electrical
Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 4.5V to 5.5V, VOUT unloaded unless otherwise specified.
LTC2637-HMI12/ LTC2637-HMI10/ LTC2637-HMI8/ LTC2637-HMX12/ LTC2637-HMX10/ LTC2637-HMX8/ LTC2637-HZ12/ LTC2637-HZ10/
LTC2637-HZ8 (VFS =4.096V)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Output Impedance
0.5
kΩ
Capacitive Load Driving
10
µF
4
mA
Short Circuit Current
VCC = 5.5V; REF Shorted to GND
Digital I/O
VIL
Low Level Input Voltage (SDA and SCL)
(Note 14)
l
–0.5
VIH
High Level Input Voltage (SDA and SCL)
(Note 11)
l
0.7VCC
0.3VCC
V
VIL(CAn)
Low Level Input Voltage on CAn
(n = 0, 1, 2)
See Test Circuit 1
l
VIH(CAn)
High Level Input Voltage on CAn
(n = 0, 1, 2)
See Test Circuit 1
l
RINH
Resistance from CAn (n=0, 1,2)
to VCC to Set CAn = VCC
See Test Circuit 2
l
10
kΩ
RINL
Resistance from CAn (n=0, 1,2)
to GND to Set CAn = GND
See Test Circuit 2
l
10
kΩ
RINF
Resistance from CAn (n=0, 1,2)
to VCC or GND to Set CAn = Float
See Test Circuit 2
l
2
VOL
Low Level Output Voltage
Sink Current = 3mA
l
0
0.4
V
tOF
Output Fall Time
VO = VIH(MIN) to VO = VIL(MAX),
CB = 10pF to 400pF (Note 12)
l
20 + 0.1CB
250
ns
tSP
Pulse Width of Spikes Suppressed
by Input Filter
l
0
50
ns
IIN
Input Leakage
0.1VCC ≤ VIN ≤ 0.9VCC
l
±1
µA
CIN
I/O Pin Capacitance
(Note 8)
l
10
pF
CB
Capacitive Load for Each Bus Line
l
400
pF
CCAn
External Capacitive Load on Address
Pin CAn (n=0, 1,2)
l
10
pF
V
0.15VCC
0.85VCC
V
V
MΩ
AC Performance
tS
Settling Time
VCC = 3V (Note 9)
±0.39% (±1LSB at 8 Bits)
±0.098% (±1LSB at 10 Bits)
±0.024% (±1LSB at 12 Bits)
Voltage Output Slew Rate
1
Capacitive Load Driving
Glitch Impulse
en
3.9
4.3
5
500
At Mid-Scale Transition
µs
µs
µs
V/µs
pF
3
nV•s
DAC-to-DAC Crosstalk
1 DAC held at FS, 1 DAC Switched 0 to FS
3
nV•s
Multiplying Bandwidth
External Reference
320
kHz
Output Voltage Noise Density
At f = 1kHz, External Reference
At f = 10kHz, External Reference
At f = 1kHz, Internal Reference
At f = 10kHz, Internal Reference
180
160
250
230
nV/√Hz
nV/√Hz
nV/√Hz
nV/√Hz
Output Voltage Noise
0.1Hz to 10Hz, External Reference
0.1Hz to 10Hz, Internal Reference
0.1Hz to 200kHz, External Reference
0.1Hz to 200kHz, Internal Reference
35
50
680
750
µVP-P
µVP-P
µVP-P
µVP-P
2637fa
LTC2637
timing
Characteristics
The l denotes specifications that apply over the full operating temperature range,
otherwise specifications are at TA = 25°C. VCC =4.5V to 5.5V. (See Figure 1) (Note 13).
LTC2637-HMI12/ LTC2637-HMI10/ LTC2637-HMI8/ LTC2637-HMX12/ LTC2637-HMX10/ LTC2637-HMX8/ LTC2637-HZ12/ LTC2637-HZ10/
LTC2637-HZ8 (VFS =4.096V)
SYMBOL
PARAMETER
fSCL
SCL Clock Frequency
CONDITIONS
l
0
tHD(STA)
Hold Time (Repeated) Start Condition
l
0.6
µs
tLOW
Low Period of the SCL Clock Pin
l
1.3
µs
tHIGH
High Period of the SCL Clock Pin
l
0.6
µs
tSU(STA)
Set-Up Time for a Repeated Start Condition
l
0.6
tHD(DAT)
Data Hold Time
l
0
tSU(DAT)
Data Set-Up Time
l
100
tr
Rise Time of Both SDA and SCL Signals
(Note 12)
l
20 + 0.1CB
300
ns
tf
Fall Time of Both SDA and SCL Signals
(Note 12)
l
20 + 0.1CB
300
ns
tSU(STO)
Set-Up Time for Stop Condition
l
0.6
µs
tBUF
Bus Free Time Between a Stop and Start Condition
l
1.3
µs
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All voltages are with respect to GND.
Note 3: High temperatures degrade operating lifetimes. Operating lifetime
is derated at temperatures greater than 105°C.
Note 4: Linearity and monotonicity are defined from code kL to code 2N–1,
where N is the resolution and kL is given by kL = 0.016•(2N/ VFS), rounded
to the nearest whole code. For VFS = 2.5V and N = 12, kL = 26 and linearity
is defined from code 26 to code 4,095. For VFS = 4.096V and N = 12, kL =
16 and linearity is defined from code 16 to code 4,095.
Note 5: Inferred from measurement at code 16 (LTC2637-12), code 4
(LTC2637-10) or code 1 (LTC2637-8), and at full-scale.
Note 6: This IC includes current limiting that is intended to protect the
device during momentary overload conditions. Junction temperature can
exceed the rated maximum during current limiting. Continuous operation
above the specified maximum operating junction temperature may impair
device reliability.
MIN
TYP
MAX
UNITS
400
kHz
µs
0.9
µs
ns
Note 7: Digital inputs at 0V or VCC.
Note 8: Guaranteed by design and not production tested.
Note 9: Internal Reference mode. DAC is stepped 1/4 scale to 3/4 scale
and 3/4 scale to 1/4 scale. Load is 2kΩ in parallel with 100pF to GND.
Note 10: Temperature coefficient is calculated by dividing the maximum
change in output voltage by the specified temperature range.
Note 11: Maximum VIH = VCC(MAX) + 0.5V.
Note 12: CB = Capacitance of one bus line in pF.
Note 13: All values refer to VIH = VIN(MIN) and VIL = VIL(MAX) levels.
Note 14: Minimum VIL exceeds Absolute Maximum rating. This condition
won’t damage the IC, but could degrade performance.
Note 15: Thermal resistance of MSOP package limits IOUT to
–5mA ≤ IOUT ≤ 5mA for H-grade MSOP parts and VCC = 5V ±10%.
2637fa
10
LTC2637
Typical Performance Characteristics
TA = 25°C, unless otherwise noted. LTC2637-L12 (Internal Reference, VFS = 2.5V)
Integral Nonlinearity (INL)
1.0
Differential Nonlinearity (DNL)
1.0
VCC = 3V
0.5
DNL (LSB)
INL (LSB)
0.5
0
–0.5
–1.0
VCC = 3V
0
–0.5
1024
0
3072
2048
CODE
–1.0
4095
1024
0
3072
2048
CODE
4095
2637 G01
INL vs Temperature
INL (POS)
0.5
0
INL (NEG)
–0.5
–1.0
–50 –25
1.260
VCC = 3V
DNL (POS)
0
DNL (NEG)
–0.5
0
25 50 75 100 125 150
TEMPERATURE (°C)
1.250
1.245
–1.0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
2637 G03
1.240
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
2637 G04
Settling to ±1LSB Rising
2637 G05
Settling to ±1LSB Falling
9TH CLOCK OF
3RD DATA BYTE
SCL
5V/DIV
VCC = 3V
1.255
VREF (V)
INL (LSB)
1.0
VCC = 3V
0.5
Reference Output Voltage
vs Temperature
DNL vs Temperature
DNL (LSB)
1.0
2637 G02
3/4 SCALE TO
1/4 SCALE STEP
VCC = 3V, VFS = 2.5V
RL = 2k, CL = 100pF
AVERAGE OF 256 EVENTS
VOUT
1LSB/DIV
4.5µs
3.6µs
VOUT
1LSB/DIV
1/4 SCALE TO
3/4 SCALE STEP
VCC = 3V, VFS = 2.5V
RL = 2k, CL = 100pF
AVERAGE OF 256 EVENTS
2µs/DIV
2637 G06
SCL
5V/DIV
9TH CLOCK OF
3RD DATA BYTE
2µs/DIV
2637 G07
2637fa
11
LTC2637
Typical Performance Characteristics
TA = 25°C, unless otherwise noted. LTC2637-H12 (Internal Reference, VFS = 4.096V)
Integral Nonlinearity (INL)
1.0
Differential Nonlinearity (DNL)
1.0
VCC = 5V
0.5
DNL (LSB)
INL (LSB)
0.5
0
–0.5
–1.0
VCC = 5V
0
–0.5
1024
0
3072
2048
CODE
–1.0
4095
0
1024
3072
2048
CODE
4095
2637 G08
INL vs Temperature
1.0
VCC = 5V
INL (POS)
INL (NEG)
–0.5
DNL (POS)
0
DNL (NEG)
25 50 75 100 125 150
TEMPERATURE (°C)
–1.0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
2637 G10
2.028
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
2637 G12
2637 G11
Settling to ±1LSB Rising
Settling to ±1LSB Falling
9TH CLOCK OF
3RD DATA BYTE
SCL
5V/DIV
2.048
2.038
–0.5
0
VCC = 5V
2.058
0.5
0
–1.0
–50 –25
2.068
VCC = 5V
VREF (V)
INL (LSB)
0.5
Reference Output Voltage
vs Temperature
DNL vs Temperature
DNL (LSB)
1.0
2637 G09
3/4 SCALE TO
1/4 SCALE STEP
VCC = 5V, VFS = 4.095V
RL = 2k, CL = 100pF
AVERAGE OF 256 EVENTS
VOUT
1LSB/DIV
5µs
4.1µs
VOUT
1LSB/DIV
1/4 SCALE TO
3/4 SCALE STEP
VCC = 5V, VFS = 4.095V
RL = 2k, CL = 100pF
AVERAGE OF 256 EVENTS
2µs/DIV
2637 G13
SCL
5V/DIV
9TH CLOCK OF
3RD DATA BYTE
2µs/DIV
2637 G14
2637fa
12
LTC2637
Typical Performance Characteristics
TA = 25°C, unless otherwise noted.
LTC2637-10
Integral Nonlinearity (INL)
1.0
Differential Nonlinearity (DNL)
1.0
VCC = 3V
VFS = 2.5V
INTERNAL REF.
0.5
DNL (LSB)
INL (LSB)
0.5
0
–0.5
–1.0
0
–0.5
256
0
768
512
CODE
–1.0
1023
VCC = 3V
VFS = 2.5V
INTERNAL REF.
DNL (LSB)
INL (LSB)
–0.25
0
–0.25
64
0
192
128
CODE
–0.50
255
64
0
192
128
CODE
2637 G17
LTC2637
Current Limiting
0.20
VCC = 5V (LTC2637-H)
VCC = 5V (LTC2637-L)
VCC = 3V (LTC2637-L)
0.15
0.10
4
$VOUT (V)
2
0
–2
–4
INTERNAL REF.
CODE = MID-SCALE
–8
–10
–30
Offset Error vs Temperature
3
VCC = 5V (LTC2637-H)
VCC = 5V (LTC2637-L)
VCC = 3V (LTC2637-L)
2
0.05
0
–0.05
–0.01
–6
–20
–10
0
10
IOUT (mA)
20
30
2637 G19
–0.15
–0.20
–30
INTERNAL REF.
CODE = MID-SCALE
–20
255
2637 G18
OFFSET ERROR (mV)
Load Regulation
$VOUT (mV)
VCC = 3V
VFS = 2.5V
INTERNAL REF.
0.25
0
–0.50
1023
Differential Nonlinearity (DNL)
0.50
0.25
6
768
512
CODE
2637 G16
Integral Nonlinearity (INL)
0.50
8
256
0
2637 G15
LTC2637-8
10
VCC = 3V
VFS = 2.5V
INTERNAL REF.
–10
0
10
IOUT (mA)
20
30
2637 G20
1
0
–1
–2
–3
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
2637 G21
2637fa
13
LTC2637
Typical Performance Characteristics
TA = 25°C, unless otherwise noted.
LTC2637
Large-Signal Response
Mid-Scale Glitch Impulse
Power-On Reset Glitch
LTC2637-L
9TH CLOCK OF
3RD DATA BYTE
SCL
5V/DIV
VCC
2V/DIV
VOUT
0.5V/DIV
LTC2637-H12
VCC = 5V, 3nV•s TYP
VOUT
5mV/DIV
ZERO-SCALE
VOUT
5mV/DIV
LTC2637-L12
VCC = 3V, 2.1nV•s TYP
VFS = VCC = 5V
1/4 SCALE to 3/4 SCALE
2µs/DIV
2637 G23
2µs/DIV
200µs/DIV
2637 G22
2637 G24
Headroom at Rails
vs Output Current
Exiting Power-Down to Mid-Scale
Power-On Reset to Mid-Scale
5.0
5V SOURCING
4.5
3.5
3V (LTC2637-L) SOURCING
3.0
LTC2637-H
2.5
2.0
1.5
DACs A TO G IN
POWER-DOWN
MODE
5V SINKING
1.0
0
0
1
2
3
4 5 6
IOUT (mA)
7
8
9
200µs/DIV
2637 G27
DAC to DAC Crosstalk (Dynamic)
Multiplying Bandwidth
2
9TH CLOCK OF
3RD DATA BYTE
0
–2
SCL
LTC2637-H12
5V/DIV
VCC = 5V, 3nV•s TYP
CREF = 0.1µF
1 DAC
SWITCH 0 TO FS
2V/DIV
1.4
VCC = 5V
1.2
1.0
VCC = 3V
(LTC2637-L)
–4
–6
–8
–10
–12
VOUT
2mV/DIV
0.8
0.6
2637 G26
2637 G25
SWEEP SDA, SCL,
BETWEEN 0V AND VCC
1.6
LTC2637-L
LTC2637H
VCC = 5V
INTERNAL REF
5µs/DIV
10
Supply Current vs Logic Voltage
1.8
VOUT
0.5V/DIV
VOUT
0.5V/DIV
3V (LTC2637-L) SINKING
0.5
ICC (mA)
VCC
2V/DIV
dB
VOUT (V)
9TH CLOCK OF
3RD DATA BYTE
SCL
5V/DIV
4.0
VCC = 5V
VREF(DC) = 2V
VREF(AC) = 0.2VP-P
CODE = FULL-SCALE
–14
–16
0
1
2
3
LOGIC VOLTAGE (V)
4
5
2637 G28
2µs/DIV
2637 G29
–18
1k
10k
100k
FREQUENCY (Hz)
1M
2637 G30
2637fa
14
LTC2637
Typical Performance Characteristics
TA = 25°C, unless otherwise noted.
LTC2637
Gain Error vs. Temperature
Noise Voltage vs. Frequency
500
0.5
NOISE VOLTAGE (nV/√Hz)
GAIN ERROR (%FSR)
1.0
0
–0.5
–1.0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
400
VCC = 5V
CODE = MID-SCALE
INTERNAL REF.
300
LTC2637-H
200
LTC2637-L
100
0
100
1k
10k
100k
FREQUENCY (Hz)
2637 G31
2637 G32
0.1Hz to 10Hz Voltage Noise
Gain Error vs Reference Input
1.0
VCC = 5V, VFS = 2.5V
CODE = MID-SCALE
INTERNAL REF.
VCC = 5.5V
0.8 GAIN ERROR OF 8 CHANNELS
0.6
GAIN ERROR (%FSR)
1M
0.4
0.2
10µV/DIV
0
–0.2
–0.4
–0.6
–0.8
–1.0
1
1.5
2 2.5 3 3.5 4 4.5
REFERENCE VOLTAGE (V)
5
5.5
1s/DIV
2637 G35
2637 G34
2637fa
15
LTC2637
Pin Functions
(DFN/MSOP)
VCC (Pin 1/Pin 1): Supply Voltage Input. 2.7V ≤ VCC ≤ 5.5V
(LTC2637-L) or 4.5V ≤ VCC ≤ 5.5V (LTC2637-H). Bypass
to GND with a 0.1µF capacitor.
VOUTA to VOUTH (Pins 2–5, 10–13/Pins 2–5, 12–15): DAC
Analog Voltage Outputs.
CAO (Pin 6/Pin 7): Chip Address Bit 0. Tie this pin to VCC,
GND or leave it floating to select an I2C slave address for
the part (See Tables 1 and 2).
SCL (Pin 7/Pin 8): Serial Clock Input Pin. Data is shifted
into the SDA pin at the rising edges of the clock. This
high impedance pin requires a pull-up resistor or current
source to VCC.
SDA (Pin 8/Pin 9): Serial Data Bidirectional Pin. Data is
shifted into the SDA pin and acknowledged by the SDA
pin. This pin is high impedance while data is shifted in.
Open drain N-channel output during acknowledgment. SDA
requires a pull-up resistor or current source to VCC.
REF (Pin 9/Pin 11): Reference Voltage Input or Output.
When External Reference mode is selected, REF is an input
(1V ≤ VREF ≤ VCC) where the voltage supplied sets the
full-scale DAC output voltage. When Internal Reference
is selected, the 10ppm/°C 1.25V (LTC2637-L) or 2.048V
(LTC2637-H) internal reference (half full-scale) is available
at the pin. This output may be bypassed to GND with up
to 10µF, and must be buffered when driving external DC
load current.
GND (Pin 14/Pin 16): Ground.
CA2 (Pin 6, MSOP only): Chip Address Bit 2. Tie this pin
to VCC, GND or leave it floating to select an I2C slave address for the part (See Table 1).
CA1 (Pin 10, MSOP only): Chip Address Bit 1. Tie this
pin to VCC, GND or leave it floating to select an I2C slave
address for the part (See Table 1).
Exposed Pad (Pin 15, DFN Only): Ground. Must be
soldered to PCB Ground.
2637fa
16
LTC2637
Block Diagram
SWITCH
INTERNAL REFERENCE
REF
VREF
GND
REGISTER
REGISTER
DAC A
REGISTER
VOUTA
REGISTER
VCC
DAC H
REGISTER
REGISTER
REGISTER
REGISTER
DAC G
REGISTER
REGISTER
REGISTER
REGISTER
DAC F
REGISTER
REGISTER
REGISTER
DAC B
REGISTER
VOUTB
VOUTC
DAC C
VREF
VOUTD
DAC D
DAC E
VOUTF
VREF
VOUTE
POWER-ON RESET
CAO
(CA2)
VOUTG
VREF
VREF
(CA1)
VOUTH
VREF
VREF
DECODE
I2C
ADDRESS
DECODE
SCL
SDA
I2C INTERFACE
( ) MSOP PACKAGE ONLY
2637 BD
Test Circuits
Test Circuit 1
Test Circuit 2
VDD
100Ω
CAn
VIH(CAn)/VIL(CAn)
RINH/RINL/RINF
2637 TC01
CAn
GND
2637 TC01b
2637fa
17
18
SCL
START
A5
2
A6
1
3
A4
4
A3
5
A2
SLAVE ADDRESS
6
A1
tf
7
A0
SCL
SDA
tHD(STA)
tHD(DAT)
tr
tHIGH
tSU(DAT)
tf
tSU(STA)
8
W
9
ACK
1
C3
2
C2
3
C1
5
A3
6
A2
7
A1
8
A0
9
ACK
1
2
3
4
5
2ND DATA BYTE
tHD(STA)
Figure 2. Typical LTC2637 Write Transaction
4
C0
1ST DATA BYTE
Sr
Figure 1. I2C Timing
ALL VOLTAGE LEVELS REFER TO VIH(MIN) AND VIL(MAX) LEVELS
S
tLOW
6
7
tSU(STO)
tSP
tr
8
P
9
ACK
tBUF
1
S
2
2637 F01
3
4
5
X
3RD DATA BYTE
6
X
7
X
8
X
9
ACK
2637 F02
LTC2637
Timing Diagram
2637fa
LTC2637
Operation
The LTC2637 is a family of octal voltage output DACs in
14-lead DFN and 16-lead MSOP packages. Each DAC can
operate rail-to-rail using an external reference, or with its
full-scale voltage set by an integrated reference. Eighteen
combinations of accuracy (12-, 10-, and 8-bit), power-on
reset value (zero-scale, mid-scale in internal reference
mode, or mid-scale in external reference mode), and fullscale voltage (2.5V or 4.096V) are available. The LTC2637
is controlled using a 2-wire I2C interface.
Power-On Reset
The LTC2637-HZ/ LTC2637-LZ clear the output to zero-scale
when power is first applied, making system initialization
consistent and repeatable.
For some applications, downstream circuits are active
during DAC power-up, and may be sensitive to nonzero
outputs from the DAC during this time. The LTC2637
contains circuitry to reduce the power-on glitch: the
analog output typically rises less than 5mV above zeroscale during power on. In general, the glitch amplitude
decreases as the power supply ramp time is increased.
See “Power-On Reset Glitch” in the Typical Performance
Characteristics section.
Transfer Function
The digital-to-analog transfer function is:
 k 
VOUT(IDEAL) =  N  VREF
2 
where k is the decimal equivalent of the binary DAC
input code, N is the resolution, and VREF is either 2.5V
(LTC2637-LMI/LTC2637-LMX/LTC2637-LZ) or 4.096V
(LTC2637-HMI/LTC2637-HMX/LTC2637-HZ) when in
Internal Reference mode, and the voltage at REF when in
External Reference mode.
I2C Serial Interface
The LTC2637 communicates with a host using the standard 2-wire I2C interface. The timing diagrams (Figures
1 and 2) show the timing relationship of the signals on
the bus. The two bus lines, SDA and SCL, must be high
when the bus is not in use. External pull-up resistors or
current sources are required on these lines. The value of
these pull-up resistors is dependent on the power supply
and can be obtained from the I2C specifications. For an I2C
bus operating in the fast mode, an active pull-up will be
necessary if the bus capacitance is greater than 200pF.
The LTC2637-HMI/LTC2637-HMX/LTC2637-LMI/
LTC2637‑LMX provide an alternative reset, setting the
output to mid-scale when power is first applied. The
LTC2637-LMI and LTC2637-HMI power up in internal
reference mode, with the output set to a mid-scale voltage of 1.25V and 2.048V, respectively. The LTC2637-LMX
and LTC2637-HMX power-up in external reference mode,
with the output set to mid-scale of the external reference.
Default reference mode selection is described in the Reference Modes section.
The LTC2637 is a receive-only (slave) device. The master
can write to the LTC2637. The LTC2637 will not acknowledge (NAK) a read request from the master.
Power Supply Sequencing
When the master has finished communicating with the
slave, it issues a STOP condition. A STOP condition is
generated by transitioning SDA from low to high while
SCL is high. The bus is then free for communication with
another I2C device.
The voltage at REF (Pin 9, DFN; Pin 11, MSOP) must be
kept within the range –0.3V ≤ VREF ≤ VCC + 0.3V (see
Absolute Maximum Ratings). Particular care should be
taken to observe these limits during power supply turnon and turn-off sequences, when the voltage at VCC is in
transition.
START (S) and STOP (P) Conditions
When the bus is not in use, both SCL and SDA must be
high. A bus master signals the beginning of a communication to a slave device by transmitting a START condition. A
START condition is generated by transitioning SDA from
high to low while SCL is high.
2637fa
19
LTC2637
Operation
Acknowledge
The Acknowledge (ACK) signal is used for handshaking
between the master and the slave. An ACK (active LOW)
generated by the slave lets the master know that the latest byte of information was properly received. The ACK
related clock pulse is generated by the master. The master
releases the SDA line (HIGH) during the ACK clock pulse.
The slave-receiver must pull down the SDA bus line during the ACK clock pulse so that it remains a stable LOW
during the HIGH period of this clock pulse. The LTC2637
responds to a write by a master in this manner but does
not acknowledge a read operation; in that case, SDA is
retained HIGH during the period of the ACK clock pulse.
Chip Address
The state of pins CA0, CA1 and CA2 (CA1 and CA2 are
only available on the MSOP package) determines the slave
address of the part. These pins can each be set to any
one of three states: VCC, GND or float. This results in 27
(MSOP Package) or 3 (DFN Package) selectable addresses
for the part. The slave address assignments are shown
in Tables 1 and 2.
In addition to the address selected by the address pins,
the part also responds to a global address. This address
allows a common write to all LTC2637 parts to be accomplished using one 3-byte write transaction on the
I2C bus. The global address, listed at the end of Tables 1
and 2, is a 7-bit hardwired address not selectable by CA0,
CA1 or CA2. If another global address is required, please
consult the factory.
The maximum capacitive load allowed on the address pins
(CA0, CA1 and CA2) is 10pF, as these pins are driven during
address detection to determine if they are floating.
Table 1. Slave Address Map (MSOP Package)
CA2
CA1
CA0
A6
A5
A4
A3
A2
A1
A0
GND
GND
GND
0
0
1
0
0
0
0
GND
GND
FLOAT
0
0
1
0
0
0
1
GND
GND
VCC
0
0
1
0
0
1
0
GND
FLOAT
GND
0
0
1
0
0
1
1
GND
FLOAT
FLOAT
0
1
0
0
0
0
0
GND
FLOAT
VCC
0
1
0
0
0
0
1
GND
VCC
GND
0
1
0
0
0
1
0
GND
VCC
FLOAT
0
1
0
0
0
1
1
GND
VCC
VCC
0
1
1
0
0
0
0
FLOAT
GND
GND
0
1
1
0
0
0
1
FLOAT
GND
FLOAT
0
1
1
0
0
1
0
FLOAT
GND
VCC
0
1
1
0
0
1
1
FLOAT
FLOAT
GND
1
0
0
0
0
0
0
FLOAT
FLOAT
FLOAT
1
0
0
0
0
0
1
FLOAT
FLOAT
VCC
1
0
0
0
0
1
0
FLOAT
VCC
GND
1
0
0
0
0
1
1
FLOAT
VCC
FLOAT
1
0
1
0
0
0
0
FLOAT
VCC
VCC
1
0
1
0
0
0
1
VCC
GND
GND
1
0
1
0
0
1
0
VCC
GND
FLOAT
1
0
1
0
0
1
1
VCC
GND
VCC
1
1
0
0
0
0
0
VCC
FLOAT
GND
1
1
0
0
0
0
1
VCC
FLOAT
FLOAT
1
1
0
0
0
1
0
VCC
FLOAT
VCC
1
1
0
0
0
1
1
VCC
VCC
GND
1
1
1
0
0
0
0
VCC
VCC
FLOAT
1
1
1
0
0
0
1
VCC
VCC
VCC
1
1
1
0
0
1
0
1
1
1
0
0
1
1
GLOBAL ADDRESS
Table 2. Slave Address Map (DFN Package)
CA0
A6
A5
A4
A3
A2
A1
A0
GND
0
0
1
0
0
0
0
FLOAT
0
0
1
0
0
0
1
VCC
0
0
1
0
0
1
0
GLOBAL ADDRESS
1
1
1
0
0
1
1
2637fa
20
LTC2637
Operation
Write Word Protocol
The master initiates communication with the LTC2637
with a START condition and a 7-bit slave address followed
by the Write bit (W) = 0. The LTC2637 acknowledges by
pulling the SDA pin low at the 9th clock if the 7-bit slave
address matches the address of the part (set by CA0, CA1
or CA2) or the global address. The master then transmits
three bytes of data. The LTC2637 acknowledges each byte
of data by pulling the SDA line low at the 9th clock of each
data byte transmission. After receiving three complete bytes
of data, the LTC2637 executes the command specified in
the 24-bit input word.
If more than three data bytes are transmitted after a valid
7-bit slave address, the LTC2637 does not acknowledge the
extra bytes of data (SDA is high during the 9th clock).
The format of the three data bytes is shown in Figure
3. The first byte of the input word consists of the 4-bit
command, followed by the 4-bit DAC address. The next
two bytes contain the 16-bit data word, which consists
of the 12-, 10- or 8-bit input code, MSB to LSB, followed
by 4, 6 or 8 don’t-care bits (LTC2637-12, LTC2637-10
and LTC2637-8, respectively). A typical LTC2637 write
transaction is shown in Figure 4.
The command bit assignments (C3-C0) and address (A3A0) assignments are shown in Tables 3 and 4. The first
four commands in the table consist of write and update
operations. A write operation loads a 16-bit data word
from the 32-bit shift register into the input register. In an
update operation, the data word is copied from the input
register to the DAC register. Once copied into the DAC
register, the data word becomes the active 12-, 10-, or
8-bit input code, and is converted to an analog voltage at
the DAC output. Write to and Update combines the first
two commands. The Update operation also powers up the
DAC if it had been in power-down mode. The data path
and registers are shown in the Block Diagram.
Table 3. Command Codes
COMMAND*
C3
C2
C1
C0
0
0
0
0
Write to Input Register n
0
0
0
1
Update (Power Up) DAC Register n
0
0
1
0
Write to Input Register n, Update (Power Up) All
0
0
1
1
Write to and Update (Power Up) DAC Register n
0
1
0
0
Power Down n
0
1
0
1
Power Down Chip (All DAC’s and Reference)
0
1
1
0
Select Internal Reference (Power Up Reference)
0
1
1
1
Select External Reference (Power Down Internal
Reference)
1
1
1
1
No Operation
*Command codes not shown are reserved and should not be used.
Table 4. Address Codes
ADDRESS (n)*
A3
A2
A1
A0
0
0
0
0
DAC A
0
0
0
1
DAC B
0
0
1
0
DAC C
0
0
1
1
DAC D
0
1
0
0
DAC E
0
1
0
1
DAC F
0
1
1
0
DAC G
0
1
1
1
DAC H
1
1
1
1
All DACs
*Address codes not shown are reserved and should not be used.
Reference Modes
For applications where an accurate external reference is
either not available, or not desirable due to limited space,
the LTC2637 has a user-selectable, integrated reference.
The integrated reference voltage is internally amplified
by 2x to provide the full-scale DAC output voltage range.
2637fa
21
LTC2637
Operation
Write Word Protocol for LTC2637
S
SLAVE ADDRESS
W ACK 1ST DATA BYTE ACK 2ND DATA BYTE ACK 3RD DATA BYTE ACK
INPUT WORD
Input Word (LTC2637-12)
C3
C2
C1 C0
A3
A2
P
A1
A1 D11 D10 D9
1ST DATA BYTE
D8
D7
D6
D5
D4 D3 D2 D1
2ND DATA BYTE
D0
X
X
X
X
X
X
X
X
3RD DATA BYTE
Input Word (LTC2637-10)
C3
C2
C1 C0
A3
A2
A1
A0
D9
D8
1ST DATA BYTE
D7
D6
D5
D4
D3
D2 D1 D0
X
2ND DATA BYTE
X
X
X
3RD DATA BYTE
Input Word (LTC2637-8)
C3
C2
C1 C0
A3
A2
1ST DATA BYTE
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
X
X
X
2ND DATA BYTE
X
X
X
3RD DATA BYTE
2637 F03
Figure 3. Command and Data Input Format
The LTC2637-LMI/ LTC2637-LMX/ LTC2637-LZ provides
a full-scale output of 2.5V. The LTC2637-HMI/ LTC2637HMX/ LTC2637-HZ provides a full-scale output of 4.096V.
The internal reference can be useful in applications where
the supply voltage is poorly regulated. Internal Reference
mode can be selected by using command 0110b, and is
the power-on default for LTC2637-HZ/ LTC2637-LZ, as
well as for LTC2637-HMI/ LTC2637-LMI.
The 10ppm/°C, 1.25V (LTC2637-LMI/ LTC2637-LMX/
LTC2637-LZ) or 2.048V (LTC2637-HMI/ LTC2637-HMX/
LTC2637-HZ) internal reference is available at the REF pin.
Adding bypass capacitance to the REF pin will improve
noise performance; and up to 10µF can be driven without
oscillation. The REF output must be buffered when driving
an external DC load current.
Alternatively, the DAC can operate in External Reference
mode using command 0111b. In this mode, an input voltage
supplied externally to the REF pin provides the reference
(1V ≤ VREF ≤ VCC) and the supply current is reduced. The
external reference voltage supplied sets the full-scale DAC
output voltage. External Reference mode is the power-on
default for LTC2637-HMX/ LTC2637-LMX.
The reference mode of LTC2637-HZ/ LTC2637-LZ/ LTC2637HMI/ LTC2637-LMI (internal reference power-on default),
can be changed by software command after power up. The
same is true for LTC2637-HMX/ LTC2637-LMX (external
reference power-on default).
Power-Down Mode
For power-constrained applications, power-down mode can
be used to reduce the supply current whenever less than
eight DAC outputs are needed. When in power-down, the
buffer amplifiers, bias circuits, and integrated reference
circuits are disabled, and draw essentially zero current.
The DAC outputs are put into a high-impedance state, and
the output pins are passively pulled to ground through individual 200kΩ resistors. Input and DAC register contents
are not disturbed during power down.
Any DAC channel or combination of channels can be put
into power-down mode by using command 0100b in
combination with the appropriate DAC address, (n). The
supply current is reduced approximately 10% for each DAC
powered down. The integrated reference is automatically
powered down when external reference is selected using
2637fa
22
LTC2637
Operation
command 0111b. In addition, all the DAC channels and
the integrated reference together can be put into powerdown mode using Power Down Chip command 0101b.
When the integrated reference and all DAC channels are
in power-down mode, the REF pin becomes high impedance (typically > 1GΩ). For all power-down commands
the 16-bit data word is ignored.
Normal operation resumes after executing any command
that includes a DAC update, (as shown in Table 1). The
selected DAC is powered up as its voltage output is updated. When a DAC which is in a powered-down state is
powered up and updated, normal settling is delayed. If
less than eight DACs are in a powered-down state prior
to the update command, the power-up delay time is 10µs.
However, if all eight DACs and the integrated reference
are powered down, then the main bias generation circuit
block has been automatically shut down in addition to
the DAC amplifiers and reference buffers. In this case,
the power up delay time is 12µs. The power-up of the
integrated reference depends on the command that powered it down. If the reference is powered down using the
Select External Reference Command (0111b), then it can
only be powered back up using Select Internal Reference
Command (0110b). However, if the reference was powered
down using Power Down Chip Command (0101b), then in
addition to Select Internal Reference Command (0110b),
any command that powers up the DACs will also power
up the integrated reference.
Voltage Output
The LTC2637’s DAC output integrated rail-to-rail amplifiers
have guaranteed load regulation when sourcing or sinking
up to 10mA at 5V, and 5mA at 3V.
Load regulation is a measure of the amplifier’s ability to
maintain the rated voltage accuracy over a wide range of
load current. The measured change in output voltage per
change in forced load current is expressed in LSB/mA.
DC output impedance is equivalent to load regulation, and
may be derived from it by simply calculating a change in
units from LSB/mA to ohms. The amplifier’s DC output
impedance is 0.1Ω when driving a load well away from
the rails.
When drawing a load current from either rail, the output
voltage headroom with respect to that rail is limited by
the 50Ω typical channel resistance of the output devices
(e.g., when sinking 1mA, the minimum output voltage is
50Ω • 1mA, or 50mV). See the graph “Headroom at Rails
vs. Output Current” in the Typical Performance Characteristics section.
The amplifier is stable driving capacitive loads of up to
500pF.
Rail-to-Rail Output Considerations
In any rail-to-rail voltage output device, the output is limited to voltages within the supply range.
Since the analog output of the DAC cannot go below ground,
it may limit for the lowest codes as shown in Figure 5b.
Similarly, limiting can occur near full scale when the REF
pin is tied to VCC. If VREF = VCC and the DAC full-scale error
(FSE) is positive, the output for the highest codes limits
at VCC, as shown in Figure 5c. No full-scale limiting can
occur if VREF is less than VCC–FSE.
Offset and linearity are defined and tested over the region
of the DAC transfer function where no output limiting can
occur.
Board Layout
The PC board should have separate areas for the analog and
digital sections of the circuit. A single, solid ground plane
should be used, with analog and digital signals carefully
routed over separate areas of the plane. This keeps digital
signals away from sensitive analog signals and minimizes
the interaction between digital ground currents and the
2637fa
23
LTC2637
Operation
analog section of the ground plane. The resistance from
the LTC2637 GND pin to the ground plane should be as
low as possible. Resistance here will add directly to the
effective DC output impedance of the device (typically
0.1Ω). Note that the LTC2637 is no more susceptible to
this effect than any other parts of this type; on the contrary, it allows layout-based performance improvements
to shine rather than limiting attainable performance with
excessive internal resistance.
supply is connected to the board and the DAC ground pin.
Thus the DAC ground pin becomes the common point for
analog ground, digital ground, and power ground. When
the LTC2637 is sinking large currents, this current flows
out the ground pin and directly to the power ground trace
without affecting the analog ground plane voltage.
It is sometimes necessary to interrupt the ground plane
to confine digital ground currents to the digital portion of
the plane. When doing this, make the gap in the plane only
as long as it needs to be to serve its purpose and ensure
that no traces cross over the gap.
Another technique for minimizing errors is to use a separate power ground return trace on another board layer.
The trace should run between the point where the power
SLAVE ADDRESS
COMMAND/ADDRESS
A6
A5
A4
A3 A2
A1
A0
SDA
A6
A5
A4
A3
A2
A1
A0
SCL
1
2
3
4
5
6
7
START
VOUT
W
8
MS DATA
C3
C2
C1
C0
A3
A2
A1
A0
ACK C3
C2
C1
C0
A3
A2
A1
A0 ACK
2
3
4
5
6
7
8
9
1
D11 D10 D9
9
D8
D7
LS DATA
D6
D5
D4
D3 D2
D1
D0
X
X
X
X
ACK
1
2
3
4
5
6
7
8
9
STOP
ACK
1
2
3
4
5
6
7
8
9
FULL-SCALE
VOLTAGE
ZERO-SCALE
VOLTAGE
X = DON’T CARE
2637 F04
Figure 4. Typical LTC2637 Input Waveform—Programming DAC Output for Full-Scale
VREF = VCC
POSITIVE
FSE
VREF = VCC
OUTPUT
VOLTAGE
OUTPUT
VOLTAGE
INPUT CODE
(c)
OUTPUT
VOLTAGE
0V
NEGATIVE
OFFSET
0V
0
2,048
INPUT CODE
(a)
2637 F04
4,095
INPUT CODE
(b)
Figure 5. Effects of Rail-to-Rail Operation On a DAC Transfer Curve (Shown for 12 Bits).
(a) Overall Transfer Function
(b) Effect of Negative Offset for Codes Near Zero
(c) Effect of Positive Full-Scale Error for Codes Near Full-Scale
2637fa
24
LTC2637
Typical Application
LTC2637 DACs Adjust LTC2755-16 Offsets, Amplified with LT1991 PGA to ±5V
5V
15
15V
0.1µF
0.1µF
8
7
+
5
VDD
LTC2755
IOUT1A 59
63 RCOM1
DAC A
1/2 LT1469
4
–
IOUT2A 2
6
0.1µF
15V
RFBA 60
61 ROFSA
64 RIN1
2
3
–
1/2 LT1469
+
OUTA
11
0.1µF
REF
0.1µF
–15V
2
VCC
1
DAC A
DAC H
3
DAC B
DAC G
15
–
+
DAC B
30k
OUTB
4
+
–
+
–
GND
–15V
0.1µF
VCC
LT1991
OUT
6
VOUT = ±5V
REF
VEE
5
4
0.1µF
DAC C
DAC F
DAC D
DAC E
13
–15V
5
30k
1
P1
2
P3
3
P9
7
–15V
–15V
DAC C
8
M9
9
M3
10
M1
14
30k
OUTC
1k
0.1µF
LTC2637MS-LMI12
DAC D
30k
–15V
0.1µF
15V
1
4
–15V
OUTD
2k
8
RVOSA 58
62 REFA
5V
0.1µF
12
19
I2C
BUS
9
SDA
8 SCL
7
CA0
10
CA1
CA2 6
16
GND
2637 TA02
2637fa
25
LTC2637
Package Description
DE Package
14-Lead (4mm × 3mm) Plastic DFN
(Reference LTC DWG # 05-08-1708 Rev B)
4.00 p0.10
(2 SIDES)
3.30 p0.05
3.60 p0.05
2.20 p0.05
8
R = 0.05
TYP
0.70 p0.05
0.40 p 0.10
14
3.30 p0.10
3.00 p0.10
(2 SIDES)
1.70 p 0.05
R = 0.115
TYP
1.70 p 0.10
PIN 1 NOTCH
R = 0.20 OR
0.35 s 45o
CHAMFER
PIN 1
PACKAGE
TOP MARK
OUTLINE (SEE NOTE 6)
0.25 p 0.05
0.50 BSC
(DE14) DFN 0806 REV B
7
0.75 p0.05
0.200 REF
1
0.25 p 0.05
0.50 BSC
3.00 REF
3.00 REF
0.00 – 0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WGED-3) IN JEDEC
PACKAGE OUTLINE MO-229
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
MS Package
16-Lead (4mm × 5mm) Plastic MSOP
(Reference LTC DWG # 05-08-1669 Rev Ø)
4.039 p 0.102
(.159 p .004)
(NOTE 3)
0.889 p 0.127
(.035 p .005)
5.23
(.206)
MIN
3.20 – 3.45
(.126 – .136)
0.280 p 0.076
(.011 p .003)
REF
16151413121110 9
0.254
(.010)
DETAIL “A”
3.00 p 0.102
(.118 p .004)
(NOTE 4)
4.90 p 0.152
(.193 p .006)
0o – 6o TYP
GAUGE PLANE
0.305 p 0.038
(.0120 p .0015)
TYP
0.53 p 0.152
(.021 p .006)
0.50
(.0197)
BSC
RECOMMENDED SOLDER PAD LAYOUT
DETAIL “A”
0.18
(.007)
SEATING
PLANE
1.10
(.043)
MAX
0.17 – 0.27
(.007 – .011)
TYP
1234567 8
0.50
(.0197)
BSC
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
0.86
(.034)
REF
0.1016 p 0.0508
(.004 p .002)
MSOP (MS16) 1107 REV Ø
2637fa
26
LTC2637
Revision History
REV
DATE
DESCRIPTION
PAGE NUMBER
A
10/09
Update LTC2637-12 Maximum Limits
5, 6, 8
2637fa
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.
27
LTC2637
Related Parts
PART NUMBER
DESCRIPTION
COMMENTS
LTC1660/LTC1665
Octal 10-/8-Bit VOUT DACs in 16-Pin Narrow SSOP
VCC = 2.7V to 5.5V, Micropower, Rail-to-Rail Output
LTC1663
Single 10-Bit VOUT DAC in SOT-23
VCC = 2.7V to 5.5V, 60µA, Internal reference, SMBus Interface
LTC1664
Quad 10-Bit VOUT DAC in 16-Pin Narrow SSOP
VCC = 2.7V to 5.5V, Micropower, Rail-to-Rail Output
LTC1669
Single 10-Bit VOUT DAC in SOT-23
VCC = 2.7V to 5.5V, 60µA, Internal reference, I2C Interface
LTC1821
Parallel 16-Bit Voltage Output DAC
Precision 16-Bit Settling in 2µs for 10V Step
LTC2600/LTC2610/
LTC2620
Octal 16-/14-/12-Bit VOUT DACs in 16-Lead Narrow SSOP
250µA per DAC, 2.5V to 5.5V Supply Range, Rail-to-Rail Output,
SPI Serial Interface
LTC2601/LTC2611/
LTC2621
Single 16-/14-/12-Bit VOUT DACs in 10-Lead DFN
300µA per DAC, 2.5V to 5.5V Supply Range, Rail-to-Rail Output,
SPI Serial Interface
LTC2602/LTC2612/
LTC2622
Dual 16-/14-/12-Bit VOUT DACs in 8-Lead MSOP
300µA per DAC, 2.5V to 5.5V Supply Range, Rail-to-Rail Output,
SPI Serial Interface
LTC2604/LTC2614/
LTC2624
Quad 16-/14-/12-Bit VOUT DACs in 16-Lead SSOP
250µA per DAC, 2.5V to 5.5V Supply Range, Rail-to-Rail Output,
SPI Serial Interface
LTC2605/LTC2615/
LTC2625
Octal 16-/14-/12-Bit VOUT DACs with I2C Interface
250µA per DAC, 2.7V to 5.5V Supply Range, Rail-to-Rail Output,
I2C Interface
LTC2606/LTC2616/
LTC2626
Single 16-/14-/12-Bit VOUT DACs with I2C Interface
270µA per DAC, 2.7V to 5.5V Supply Range, Rail-to-Rail Output,
I2C Interface
LTC2609/LTC2619/
LTC2629
Quad 16-/14-/12-Bit VOUT DACs with I2C Interface
250µA per DAC, 2.7V to 5.5V Supply Range, Rail-to-Rail Output
with Separate VREF Pins for Each DAC
LTC2630
Single 12-/10-/8-Bit SPI VOUT DACs with 10ppm/°C
Reference in SC70
180µA per DAC, 2.7V to 5.5V Supply Range, 10ppm/°C Reference,
Rail-to-Rail Output, SPI Interface
LTC2631
Single 12-/10-/8-Bit I2C VOUT DACs with 10ppm/°C
Reference in ThinSOT™
180µA per DAC, 2.7V to 5.5V Supply Range, 10ppm/°C Reference,
External Ref. Mode, Rail-to-Rail Output, I2C Interface
LTC2634
Quad 12-/10-/8-Bit VOUT DACs with 10ppm/°C
Reference
125µA per DAC, 2.7V to 5.5V Supply Range, 10ppm/°C Reference,
External Ref. Mode, Rail-to-Rail Output, SPI Interface
LTC2636
Octal 12-/10-/8-Bit VOUT DACs with 10ppm/°C
Reference
125µA per DAC, 2.7V to 5.5V Supply Range, 10ppm/°C Reference,
External Ref. Mode, Rail-to-Rail Output, SPI Interface
LTC2640
Single 12-/10-/8-Bit SPI VOUT DACs with 10ppm/°C
Reference in ThinSOT
180µA per DAC, 2.7V to 5.5V Supply Range, 10ppm/°C Reference,
External Ref. Mode, Rail-to-Rail Output, SPI Interface
ThinSOT is a trademark of Linear Technology Corporation
2637fa
28 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
LT 1009 REV A • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 2009