WM2614CDT データシートの表示（PDF） - Wolfson Microelectronics plc

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WM2614CDT

Quad 12-bit Serial Input Voltage Output DAC

Wolfson Microelectronics plc 

WM2614

DEVICE DESCRIPTION

Production Data Rev 1.0

GENERAL FUNCTION

The device uses a resistor string network buffered with an op amp to convert 12-bit digital data to

analogue voltage levels (see Block Diagram). The output voltage is determined by the reference input

voltage and the input code according to the following relationship:

Output voltage =

( ) CODE

2 VREF

4096

INPUT

OUTPUT

1111

1111

1111

( ) 2 VREF 4095

4096

:

:

1000

1000

0000

0000

0001

0000

( ) 2049

2 VREF

4096

( ) 2 VREF 2048 = VREF

4096

0111

1111

1111

( ) 2 VREF 2047

4096

:

:

0000

0000

0001

( )1

2 VREF

4096

0000

0000

0000

0V

Table 1 Binary Code Table (0V to 2VREFIN Output), Gain = 2

POWER ON RESET

An internal power-on-reset circuit resets the DAC register to all 0s on power-up.

BUFFER AMPLIFIER

The output buffer has a near rail-to-rail output with short circuit protection and can reliably drive a 2kΩ load

with a 100pF load capacitance.

EXTERNAL REFERENCE

The reference voltage input is buffered which makes the DAC input resistance independent of code. The

REFIN pin has an input resistance of 10MΩ and an input capacitance of typically 5pF. The reference

voltage determines the DAC full-scale output.

HARDWARE CONFIGURATION OPTIONS

The device has two configuration options that are controlled by device pins.

DEVICE POWER DOWN

The device can be powered-down by pulling pin NPD (Pin 2) high. This powers down all DACs overriding

their individual power down settings. This will reduce power consumption to typically 10nA. When the

power down function is released the device reverts to the DAC code set prior to power down.

SIMULTANEOUS DAC UPDATE

The NLDAC pin (Pin 3) can be held high to prevent serial word writes from updating the DAC latches. By

writing new values to multiple DACs then pulling NLDAC low, all new DAC codes are loaded into the DAC

latches simultaneously.

WOLFSON MICROELECTRONICS LTD

Production Data Rev 1.0 June 1999

8

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