PWM-to-voltage output DACs with an integrated high
accuracy, low drift, 10ppm/°C reference in a 16-lead
MSOP package. It has rail-to-rail output buffers and is
guaranteed monotonic.
The LTC2645 measures the period and pulse width of the
PWM input signals and updates the voltage output DACs
after each corresponding PWM input rising edge. The DAC
outputs update and settle to 12-bit accuracy within 8µs
typically and are capable of sourcing and sinking up to
5mA (3V) or 10mA (5V), eliminating voltage ripple and
replacing slow analog filters and buffer amplifiers.
The LTC2645 has a full-scale output of 2.5V using the
10ppm/°C internal reference. It can operate with an exter-
nal reference, which sets the full-scale output equal to the
external reference voltage. Each DAC enters a pin-select-
able idle state when the PWM input is held unchanged for
more than 60ms. The part operates from a single 2.7V
to 5.5V supply and supports PWM input voltages from
1.71V to 5.5V.
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. patents, including 5396245, 5859606, 6891433, 6937178, 7414561.
No Latency PWM-to-Voltage Conversion
Voltage Output Updates and Settles within 8µs
100kHz to 30Hz PWM Input Frequency
±2.5LSB Max INL; ±1LSB Max DNL (LTC2645-12)
Guaranteed Monotonic
Pin-Selectable Internal or External Reference
2.7V to 5.5V Supply Range
1.71V to 5.5V Input Voltage Range
Low Power: 4mA at 3V, <1µA Power-Down
Guaranteed Operation from –40°C to 125°C
16-Lead MSOP Package
APPLICATIONS
n
n
n
n
n
n
Digital Calibration
Trimming and Adjustment
Level Setting
Process Control and Industrial Automation
Instrumentation
Automotive
TYPICAL APPLICATION
4-Channel PWM to Voltage Output DAC
PWM INPUTS
IN
A
IN
B
IN
C
1.7V TO 5.5V
IN
D
IOV
CC
0.1µF
PD
GND
LTC2645
V
OUTA
V
OUTB
V
OUTC
V
OUTD
REF
V
CC
IDLSEL
REFSEL
GND
2645 TA01a
PWM Input to DAC Output
BUFFERED
VOLTAGE
OUTPUTS
INPUT: 1V TO 5.5V
OUTPUT: 1.25V
IN
A
2V/DIV
2.7V TO 5.5V
0.1µF
0.1µF
V
OUTA
500mV/DIV
20µs/DIV
TA01b
Document Feedback
For more information
www.analog.com
1
Rev. B
LTC2645
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
PIN CONFIGURATION
TOP VIEW
V
CC
V
OUTA
V
OUTB
IDLSEL
IN
B
IN
A
IOV
CC
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
GND
V
OUTD
V
OUTC
REFSEL
REF
IN
C
IN
D
PD
Supply Voltages (V
CC
, IOV
CC
) ...................... –0.3V to 6V
IN
A
, IN
B
, IN
C
, IN
D
......................................... –0.3V to 6V
IDLSEL,
PD,
REFSEL .................................... –0.3V to 6V
V
OUTA
, V
OUTB
, V
OUTC
,
V
OUTD
...............................–0.3V to Min (V
CC
+ 0.3V, 6V)
REF ..................................–0.3V to Min (V
CC
+ 0.3V, 6V)
Operating Temperature Range
LTC2645C ................................................ 0°C to 70°C
LTC2645I .............................................–40°C to 85°C
LTC2645H .......................................... –40°C to 125°C
Maximum Junction Temperature .......................... 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
MS PACKAGE
16-LEAD PLASTIC MSOP
(4mm × 4.9mm)
T
JMAX
= 150°C,
θ
JA
= 120°C/W
2
Rev. B
For more information
www.analog.com
LTC2645
ORDER INFORMATION
LTC2645
C
MS
–L
12
#TR
PBF
LEAD FREE DESIGNATOR
TAPE AND REEL
TR = 2,500-Piece Tape and Reel
RESOLUTION
12 = 12-Bit
10 = 10-Bit
8 = 8-Bit
FULL-SCALE VOLTAGE, INTERNAL REFERENCE MODE
L = 2.5V
PACKAGE TYPE
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
Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications.
Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
PRODUCT SELECTION GUIDE
PART NUMBER
LTC2645-L12
LTC2645-L10
LTC2645-L8
PART MARKING*
645L12
645L10
2645L8
RESOLUTION
12-Bit
10-Bit
8-Bit
CHANNELS
4
4
4
VFS WITH INTERNAL
REFERENCE
2.5V
2.5V
2.5V
MAXIMUM INL
±2.5LSB
±1.0LSB
±0.5LSB
PACKAGE DESCRIPTION
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead Plastic MSOP
*Temperature grades are identified by a label on the shipping container.
For more information
www.analog.com
3
Rev. B
LTC2645
ELECTRICAL CHARACTERISTICS
LTC2645-L12/-L10/-L8 (V
FS
= 2.5V)
LTC2645-L8
SYMBOL PARAMETER
DC Performance
Resolution
Monotonicity
DNL
INL
ZSE
V
OS
V
OSTC
GE
GE
TC
Differential
Nonlinearity
V
CC
= 3V, Internal Ref. (Note 3)
V
CC
= 3V, Internal Ref. (Note 3)
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 2.7V to 5.5V, V
OUT
unloaded unless otherwise specified.
LTC2645-L10
MIN
10
10
±0.5
±0.05
0.5
±0.5
±10
l
LTC2645-L12
MIN
12
12
TYP
MAX
UNITS
Bits
Bits
±1
±1
0.5
±0.5
±10
±2.5
5
±5
LSB
LSB
mV
mV
µV/°C
±0.8
%FSR
ppm/°C
ppm/°C
ppm/°C
0.256
LSB/mA
CONDITIONS
MIN
8
8
TYP
MAX
TYP
MAX
±0.5
±0.2
0.5
±0.5
±10
±1
5
±5
Integral Nonlinearity V
CC
= 3V, Internal Ref. (Note 3)
Zero-Scale Error
V
CC
= 3V, Internal Ref., Code = 0
Offset Error
V
OS
Temperature
Coefficient
Gain Error
Gain Temperature
Coefficient
V
CC
= 3V, Internal Ref. (Note 4)
V
CC
= 3V, Internal Ref. (Note 9)
V
CC
= 3V, Internal Ref.
V
CC
= 3V, Internal Ref. (Note 9)
C-grade
I-grade
H-grade
Internal Ref., Mid-Scale,
V
CC
= 3V ±10%,
–5mA ≤ I
OUT
≤ 5mA
V
CC
= 5V ±10%,
–10mA ≤ I
OUT
≤ 10mA
±0.5
5
±5
±0.2
10
10
10
±0.8
±0.2
10
10
10
±0.8
±0.2
10
10
10
0.14
Load Regulation
l
0.009 0.016
0.035 0.064
l
l
0.009 0.016
0.09
0.156
0.035 0.064
0.09
0.156
0.14
0.09
0.256
0.156
LSB/mA
Ω
R
OUT
DC Output
Impedance
Internal Ref., Mid-Scale,
V
CC
= 3V ±10%,
–5mA ≤ I
OUT
≤ 5mA
V
CC
= 5V ±10%,
–10mA ≤ I
OUT
≤ 10mA
l
0.09
0.156
0.09
0.156
0.09
0.156
Ω
SYMBOL PARAMETER
V
OUT
PSR
I
SC
DAC Output Span
Power Supply Rejection
Short Circuit Output Current (Note 5)
Sinking
Sourcing
Positive Supply Voltage
Digital Input Supply Voltage
Supply Current (Note 6)
CONDITIONS
External Reference
Internal Reference
V
CC
= 3V ±10% or 5V ±10%
V
FS
= V
CC
= 5.5V
Zero-Scale; V
OUT
Shorted to V
CC
Full-Scale; V
OUT
Shorted to GND
For Specified Performance
For Specified Performance
V
CC
= 3V, Internal Reference
V
CC
= 5V, Internal Reference
IOV
CC
= 5V
V
CC
= 5V,
PD
= 0V
IOV
CC
= 5V,
PD
= 0V
l
l
MIN
TYP
0 to V
REF
0 to 2.5
–80
27
–28
MAX
UNITS
V
V
dB
48
–48
5.5
5.5
mA
mA
V
mA
mA
µA
µA
µA
Power Supply
V
CC
IOV
CC
I
CC
l
l
l
l
l
l
l
2.7
1.71
4
6.4
25
0.5
0.5
5
8
50
5
5
I
CC(IOVCC)
Supply Current, IOV
CC
(Note 6)
I
SD
Supply Current in Power-Down Mode (Note 6)
I
SD(IOVCC)
Supply Current in Power-Down Mode, IOV
CC
(Note 6)
4
Rev. B
For more information
www.analog.com
LTC2645
ELECTRICAL CHARACTERISTICS
LTC2645-L12/-L10/-L8 (V
FS
= 2.5V)
SYMBOL PARAMETER
Reference Input
V
REF
Input Voltage Range
Resistance
Capacitance
I
REF
Reference Current, Power-Down Mode
Output Voltage
Reference Temperature Coefficient
Output Impedance
Capacitive Load Driving
Short Circuit Current
Digital Inputs (IN
A
, IN
B
, IN
C
, IN
D
,
PD)
V
IH
V
IL
I
LK
C
IN
t
s
Digital Input High Voltage
Digital Input Low Voltage
Digital Input Leakage
Digital Input Capacitance
Settling Time From IN
A
/IN
B
/IN
C
/IN
D
Rising Edge
(Note 8)
Voltage Output Slew Rate
Capacitive Load Driving
Glitch Impulse
DAC-to-DAC Crosstalk
Multiplying Bandwidth
e
n
Output Voltage Noise Density
At Mid-Scale Transition
1 DAC Held at FS, 1 DAC Switched 0 to FS
External Reference
At f = 1kHz, External Reference
At f = 10kHz, External Reference
At f = 1kHz, Internal Reference
At f = 10kHz, Internal Reference
0.1Hz to 10Hz, External Reference
0.1Hz to 10Hz, Internal Reference
0.1Hz to 200kHz, External Reference
0.1Hz to 200kHz, Internal Reference
C
REF
= 0.1µF
IN
A
/IN
B
/IN
C
/IN
D
= GND to IOV
CC
(Note 7)
±0.39% (±1LSB at 8 Bits)
±0.098% (±1LSB at 10 Bits)
±0.024% (±1LSB at 12 Bits)
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
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