MP7643AN View Datasheet(PDF) - Exar Corporation

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Description

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MP7643AN

4-Channel, Programmable Gain Voltage Output, 15 MHz Input Bandwidth 8-Bit DACs with Multiplying Parallel Digital Data Port

Exar Corporation 

MP7643

A1, A0

DB0 to DB7

LD

VOUT

tAS

tDS

tLD

tAH

tDH

tSD

1/2 LSB

Figure 1. Timing Diagram

1/2 LSB

A0, A1

2-4

Decoder

LD

To DAC1 Latch Enable

To DAC2 Latch Enable

To DAC3 Latch Enable

To DAC4 Latch Enable

LD A1 A0

L

L

L

↑

L

L

L

L

H

↑

L

H

L

H

L

↑

H

L

L

H

H

↑

H

H

H

X

X

Operation

DAC1 Transparent

DAC1 Latched

DAC2 Transparent

DAC2 Latched

DAC3 Transparent

DAC3 Latched

DAC4 Transparent

DAC4 Latched

No Operation

Figure 2. Input Control Logic (Simplified)

Block Diagram

Table 1. Truth Table

D7 D6 D5 D4 D3 D2 D1 D0 DAC Output Voltage

MSB

LSB

VOi

= VREFN + (VRi –

AGND) (

D

256

)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

VREFN

(VRi

– VREFN)

(

1

256

)

+

VREFN

1

1

1

1

1

1

1

0

1

1

1

1

1

1

1

1

(VRi

– VREFN)

(

254

256

)

+

VREFN

(VRi

– VREFN)

(

255

256

)

+

VREFN

Note: These outputs must be ratioed up for gain in the output amplifier.

Rev. 1.00

Table 2. DAC Transfer Function

Analog Output vs. Digital Code (With VREF Shorted to INV)

6

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