MAX5480BCEE Datasheet MAX5480BEEE+T, MAX5480ACEE+, MAX5480AEEE+ | P4-P6

MAX5480

_______________Detailed Description

The MAX5480 is an 8-bit multiplying digital-to-analog

converter (DAC) that consists of a thin-film R-2R resistor

array with CMOS current steering switches. Figure 3

shows a simplified schematic of the DAC. The inverted

R-2R ladder divides the voltage or current reference in

a binary manner among the eight steering switches.

The magnitude of the current appearing at either OUT

terminal depends on the number of switches selected;

therefore, the output is an analog representation of the

digital input. The two OUT terminals must be held at the

same potential so a constant current is maintained in

each ladder leg. This makes the REF input current inde-

pendent of switch state and also ensures that the

MAX5480 maintains its excellent linearity performance.

Interface-Logic Information

Mode Selection

The inputs CS and WR control the MAX5480’s operat-

ing mode (see Table 1).

Write Mode

When CS and WR are both low, the MAX5480 is in write

mode, and its analog output responds to data activity at

the D0–D7 data-bus inputs. In this mode, the data

latches are transparent (see Tables 2 and 3).

Hold Mode

In hold mode, the MAX5480 retains the data that was

present on D0–D7 just prior to CS or WR assuming a

high state. The analog output remains at the value cor-

responding to the digital code locked in the data latch.

__________Applications Information

Using the MAX5480 in Voltage-

Output Mode (Single Supply)

The MAX5480 can be used either as a current-output

DAC (Figures 1 and 6) or as a voltage-output DAC

(Figures 2 and 5).

To use the MAX5480 in voltage mode, connect OUT1 to

the reference input and connect OUT2 to ground. REF,

now the DAC output, is a voltage source with a con-

stant output resistance of 10kΩ (nominally). This output

is often buffered with an op amp (Figure 5).

An advantage of voltage-mode operation is single-

supply operation for the complete circuit; i.e., a nega-

tive reference is not required for a positive output. It is

important to note that the range of the reference is

restricted in voltage mode. The reference input (voltage

at OUT1) must always be positive and is limited to no

more than V

- 3V. If the reference voltage exceeds

this value, linearity is degraded.

8-Bit Parallel DAC in

QSOP-16 Package

4 _______________________________________________________________________________________

L L

MAX5480

10pF

OUT

REF

D7–D0

OUT1

DATA

INPUTS

4–11

OUT2

R1 AND R2 USED ONLY IF GAIN

ADJUSTMENT IS REQUIRED.

REF

GND

MAX4330

Figure 1. Unipolar Binary Operation (Two-Quadrant Multiplication)

MAX5480

REF

INPUT*

OUTPUT

VOLTAGE

(10kΩ OUTPUT

RESISTANCE)

OUT1 REF

13 12 3

OUT2

RFB V

+5V

GND D7–D0

4–11

DATA IN

CSWR

*(V

- 3V, max)

Figure 2. Typical Operating Circuit (Voltage Mode—Unbuffered)

MODE

Write

Hold

DAC Response

DAC responds to data bus

(D0–D7) inputs.

Data bus (D0–D7) is locked out;

DAC holds last data present

when CS or WR assumed high

state.

Table 1. Mode-Selection Table

L = Low State, H = High State, X = Don’t Care

MAX5480

8-Bit Parallel DAC in

QSOP-16 Package

_______________________________________________________________________________________ 5

INTERFACE LOGIC

S7 S6

20kΩ 20kΩ 20kΩ 20kΩ

10kΩ

D6 D5

D0 (LSB)

D7 (MSB)

20kΩ

10kΩ

REF

10kΩ

OUT2

OUT1

RFB

Figure 3. MAX5480 Functional Diagram

NOTES:

1. FOR THE MAX5480, ALL INPUT SIGNAL RISE AND FALL TIMES ARE MEASURED

FROM 10% TO 90% OF V

. V

= +5V, t

= t

= 20ns.

2. TIMING MEASUREMENT REFERENCE LEVEL IS (V

+ V

) / 2.

DATA IN

(D7–D0)

DATA IN

STABLE

Figure 4. Write-Cycle Timing Diagram

Table 2. Unipolar Binary Code Table Table 3. Bipolar (Offset Binary) Code Table

NOTE LSB V V

REF REF

: 1 2

256









( )

−

NOTE LSB V V

REF REF

: 1 2

128









( )

−

DIGITAL INPUT

MSB LSB

1 1 1 1 1 1 1 1

1 0 0 0 0 0 0 1

ANALOG OUTPUT

1 0 0 0 0 0 0 0

0 1 1 1 1 1 1 1

0 0 0 0 0 0 0 1

0 0 0 0 0 0 0 0

DIGITAL INPUT

MSB LSB

1 1 1 1 1 1 1 1

1 0 0 0 0 0 0 1

ANALOG OUTPUT

1 0 0 0 0 0 0 0

0 1 1 1 1 1 1 1

0 0 0 0 0 0 0 1

0 0 0 0 0 0 0 0

-V

255

256

REF













-V

129

256

REF













-V

128

256

REF













= −

REF

-V

127

256

REF













-V

256

REF













-V

256

REF













= 0

127

128

REF













128

REF













-V

128

REF













-V

127

128

REF













-V

128

REF













MAX5480

8-Bit Parallel DAC in

QSOP-16 Package

MAX5480

MAX4330

MAX6120

+1.2V

0V ≤ V

OUT

≤ 2.4V (255/256)

0.1µF

OUT1

1213

10k

REF

OUT2

RFB V

OUT

N.C.

+5V

GND

D7–D0

4–11

DATA IN

CSWR

Figure 5. Single-Supply Voltage-Output Mode (Buffered)

MAX5480

0 TO -V

REF

±10V

(AC OR DC)

1kΩ

2kΩ

OUT1

OUT2

NOTES:

1. ADJUST R1 FOR V

OUT

= 0V AT CODE 10000000.

2. C1 PHASE COMPENSATION (10pF to 15pF) MAY BE

REQUIRED IF A1 IS A HIGH-SPEED AMPLIFIER.

REF

RFB

GND

1/2 MXL1013

OUT

20kΩ

10kΩ

5kΩ

D7–D0

DATA

INPUTS

4–11

Figure 6. Bipolar (Four-Quadrant) Operation

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are

implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

P1-P3 P4-P6

MAX5480BCEE

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Description:

Digital to Analog Converters - DAC 8-Bit Parallel DAC in QSOP-16 Package

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MAX5480BCEE

MAX5480BCEE

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