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PDF LTC2645 Data sheet ( Hoja de datos )
| Número de pieza | LTC2645 | |
| Descripción | Quad 12-/10-/8-Bit PWM to VOUT DACs | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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1. LTC2645  Hay una vista previa y un enlace de descarga de LTC2645 (archivo pdf) en la parte inferior de esta página. Total 20 Páginas | ||
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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
1 page  
LTC2645
E lectrical 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
Reference Input
VREF Input Voltage Range
Resistance
Capacitance
IREF Reference Current, Power-Down Mode
Reference Output
Output Voltage
Reference Temperature Coefficient
Output Impedance
Capacitive Load Driving
Short Circuit Current
Digital Inputs (INA, INB, INC, IND, PD)
VIH Digital Input High Voltage
VIL Digital Input Low Voltage
ILK Digital Input Leakage
CIN Digital Input Capacitance
AC Performance
ts Settling Time From INA/INB/INC/IND Rising Edge
(Note 8)
Voltage Output Slew Rate
Capacitive Load Driving
Glitch Impulse
DAC-to-DAC Crosstalk
Multiplying Bandwidth
en Output Voltage Noise Density
Output Voltage Noise
CONDITIONS
DAC Powered Down
(Note 9)
VCC = 5.5V, REF Shorted to GND
INA/INB/INC/IND = GND to IOVCC
(Note 7)
±0.39% (±1LSB at 8 Bits)
±0.098% (±1LSB at 10 Bits)
±0.024% (±1LSB at 12 Bits)
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
CREF = 0.1µF
MIN TYP
l1
l 120
l
160
7.5
0.005
l 1.24
1.25
±10
0.5
10
2.5
l 0.8•IOVCC
l
l
l
7.0
7.4
7.8
1.0
500
2.1
0.9
320
180
160
200
180
35
40
680
730
MAX UNITS
VCC V
200 kΩ
pF
1.5 µA
1.26 V
ppm/°C
kΩ
µF
mA
V
0.5 V
±1 µA
5 pF
µs
µs
µs
V/µs
pF
nV • s
nV • s
kHz
nV/√Hz
nV/√Hz
nV/√Hz
nV/√Hz
nVP-P
nVP-P
nVP-P
nVP-P
For more information www.linear.com/LTC2645
2645f
5
5 Page 
LTC2645
Pin Functions
VCC (Pin 1): Supply Voltage Input. 2.7V ≤ VCC ≤ 5.5V.
Bypass to GND with a 0.1µF capacitor.
INA, INB, INC, IND (Pins 6, 5, 11, 10): PWM Inputs. Apply
a pulse-width modulated input frequency between 30Hz
and 6.25kHz (12-bit), 25kHz (10-bit) or 100kHz (8-bit).
After each INX rising edge, the part calculates the duty
cycle based upon the pulse width and period and updates
DAC channel VOUTX. Logic levels are referenced to IOVCC.
IOVCC (Pin 7): I/O Supply Voltage Input. 1.71V ≤ IOVCC ≤
5.5V. Bypass to GND with a 0.1µF capacitor.
IDLSEL (Pin 4): Idle Mode Select Input. Connect IDLSEL
to GND or VCC to select the behavior of the DAC output
when there has been no rising edge on the PWM input for
more than the idle mode timeout delay t3 (nominal delay
is 60ms). Available idle mode states are power-down with
high impedance output, hold previous state, zero-scale or
full-scale. This pin also selects the initial state of the DAC
outputs following a power-on reset.
PD (Pin 9): Active-Low Power-Down Input. Connect PD to
GND to place the part in power-down with a typical supply
current of <1µA. Connect PD to IOVCC for normal operation.
REFSEL (Pin 13): Reference Select Input. Connect REFSEL
to GND to select internal reference mode. Connect REFSEL
to VCC to select external reference mode.
REF (Pin 12): Reference Voltage Input or Output. When
REFSEL is connected to VCC, REF is an input (1V ≤ VREF
≤ VCC) where the voltage supplied sets the full-scale
DAC output voltage. When REFSEL is connected to GND,
the 10ppm/°C, 1.25V 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.
VOUTA, VOUTB, VOUTC, VOUTD (Pins 2, 3, 14, 15): DAC
Analog Voltage Outputs. The DAC output voltage can be
calculated by the following equation:
VOUTX = VREF • tPWHX/tPERX
where VREF is 2.5V in internal reference mode or the REF
pin voltage in external reference mode, tPWHX is the pulse
width of the preceding INX period and tPERX is the time
between the two most recent INX rising edges.
GND (Pins 8, 16): Ground.
For more information www.linear.com/LTC2645
2645f
11
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet LTC2645.PDF ] | |
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