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LTC2645-L12 Schematic ( PDF Datasheet ) - Linear Technology

Teilenummer LTC2645-L12
Beschreibung Quad 12-/10-/8-Bit PWM to VOUT DACs
Hersteller Linear Technology
Logo Linear Technology Logo 




Gesamt 20 Seiten
LTC2645-L12 Datasheet, Funktion
Features
n No Latency PWM-to-Voltage Conversion
n Voltage Output Updates and Settles within 8µs
n 100kHz to 30Hz PWM Input Frequency
n ±2.5LSB Max INL; ±1LSB Max DNL (LTC2645-12)
n Guaranteed Monotonic
n Pin-Selectable Internal or External Reference
n 2.7V to 5.5V Supply Range
n 1.71V to 5.5V Input Voltage Range
n Low Power: 4mA at 3V, <1µA Power-Down
n Guaranteed Operation from –40°C to 125°C
n 16-Lead MSOP Package
Applications
n Digital Calibration
n Trimming and Adjustment
n Level Setting
n Process Control and Industrial Automation
n Instrumentation
n Automotive
LTC2645
Quad 12-/10-/8-Bit PWM
to VOUT DACs with
10ppm/°C Reference
Description
The LTC®2645 is a family of quad 12-, 10-, and 8-bit 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-selectable
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.
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.
Typical Application
4-Channel PWM to Voltage Output DAC
PWM INPUTS
1.7V TO 5.5V
0.1µF
INA VOUTA
INB VOUTB
INC VOUTC
IND VOUTD
LTC2645
IOVCC
REF
PD VCC
GND IDLSEL
REFSEL
2.7V TO 5.5V
0.1µF
GND
2645 TA01a
BUFFERED
VOLTAGE
OUTPUTS
INPUT: 1V TO 5.5V
OUTPUT: 1.25V
0.1µF
INA
2V/DIV
VOUTA
500mV/DIV
PWM Input to DAC Output
20µs/DIV
TA01b
For more information www.linear.com/LTC2645
2645f
1






LTC2645-L12 Datasheet, Funktion
LTC2645
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.
LTC2645-L12/-L10/-L8 (VFS = 2.5V)
SYMBOL PARAMETER
tPWH INA/INB/INC/IND High Time
tPWL INA/INB/INC/IND Low Time
tPER INA/INB/INC/IND Rising Edge to Rising Edge
Period
t3 INA/INB/INC/IND Idle Mode Timeout
t4 INA/INB/INC/IND Rising Edge to DAC Update
Delay
fMAX INA/INB/INC/IND Frequency
CONDITIONS
LTC2645-L12
LTC2645-L10
LTC2645-L8
LTC2645-L12
LTC2645-L10
LTC2645-L8
MIN TYP MAX UNITS
l 25
ns
l 25
ns
l 0.160
33 ms
l 0.040
33 ms
l 0.010
33 ms
l 50
70 ms
3.2 µs
l 0.03
l 0.03
l 0.03
6.25 kHz
25 kHz
100 kHz
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 with respect to GND.
Note 3: Linearity and monotonicity are defined from code 16 to code 4095
(LTC2645-12), code 4 to code 1023 (LTC2645-10) or code 1 to code 255
(LTC2645-8).
Note 4: Inferred from measurement at code 16 (LTC2645-12), code 4
(LTC2645-10) or code 1 (LTC2645-8), and at full-scale.
Note 5: 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.
Note 6: INx at 0V or IOVCC.
Note 7: Guaranteed by design and not production tested.
Note 8: Internal Reference mode. DAC is stepped ¼ scale to ¾ scale and
¾ scale to ¼ scale. Load is 2kΩ in parallel with 100pF to GND.
Note 9: Temperature coefficient is calculated by dividing the maximum
change in output voltage by the specified temperature range.
2645f
6 For more information www.linear.com/LTC2645

6 Page









LTC2645-L12 pdf, datenblatt
LTC2645
Block Diagram
IOVCC
IDLSEL
PD
INA
INB
INC
IND
GND
INTERNAL REFERENCE
PWM TO BINARY
CONVERSION
PWM TO BINARY
CONVERSION
PWM TO BINARY
CONVERSION
PWM TO BINARY
CONVERSION
SWITCH
VREF
DAC A
REFSEL
REF
VCC
VOUTA
DAC B
VOUTB
DAC C
VOUTC
DAC D
VOUTD
GND
2645 BD
12
For more information www.linear.com/LTC2645
2645f

12 Page





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