2645L8 查看數據表（PDF） - Linear Technology

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2645L8

Quad 12-/10-/8-Bit PWM to VOUT DACs with 10ppm/°C Reference

Linear Technology 

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

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