Rainbow Electronics MAX5144 User Manual

Page 1

General Description

The MAX5141–MAX5144 are serial-input, voltage-output, 14-bit digital-to-analog converters (DACs) in tiny µMAX packages, 50% smaller than comparable DACs in an 8-pin SO. They operate from low +3V (MAX5143/ MAX5144) or +5V (MAX5141/MAX5142) single supplies. They provide 14-bit performance (±1LSB INL and DNL) over temperature without any adjustments. The DAC output is unbuffered, resulting in a low supply current of 120µA and a low offset error of 2LSBs.

The DAC output range is 0V to V

REF.

For bipolar operation, matched scaling resistors are provided in the MAX5142/MAX5144 for use with an external precision op amp (such as the MAX400), generating a ±V

REF

output

swing. A 16-bit serial word is used to load data into the DAC

latch. The 25MHz, 3-wire serial interface is compatible with SPI™/QSPI™/MICROWIRE™, and can interface directly with optocouplers for applications requiring isolation. A power-on reset circuit clears the DAC output to code 0 (MAX5141/MAX5143) or code 8192 (MAX5142/ MAX5144) when power is initially applied.

A logic low on CLR asynchronously clears the DAC output to code 0 (MAX5141/MAX5143) or code 8192 (MAX5142/MAX5144), independent of the serial interface.

The MAX5141/MAX5143 are available in 8-pin µMAX packages and the MAX5142/MAX5144 are available in 10-pin µMAX packages.

Applications

High-Resolution and Gain Adjustment

Industrial Process Control

Automated Test Equipment

Data-Acquisition Systems

Features

♦ Miniature (3mm x 5mm) 8-Pin µMAX Package

♦ Low 120µA Supply Current

♦ Fast 1µs Settling Time

♦ 25MHz SPI/QSPI/MICROWIRE-Compatible Serial

Interface

♦ V

REF

Range Extends to V

♦ +5V (MAX5141/MAX5142) or +3V

(MAX5143/MAX5144) Single-Supply Operation

♦ Full 14-Bit Performance Without Adjustments ♦ Unbuffered Voltage Output Directly Drives 60kΩ

Loads

♦ Power-On Reset Circuit Clears DAC Output to

Code 0 (MAX5141/MAX5143) or Code 8192 (MAX5142/MAX5144)

♦ Schmitt-Trigger Inputs for Direct Optocoupler

Interface

♦ Asynchronous CLR

MAX5141–MAX5144

+3V/+5V, Serial-Input,

Voltage-Output, 14-Bit DACs

________________________________________________________________ Maxim Integrated Products 1

19-1849; Rev 1; 5/01

Ordering Information

SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp.

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Pin Configurations

TOP VIEW

REF

SCLK

DIN

REF

SCLK

DIN

CLR

MAX5142

MAX5144

µMAX

MAX5141 MAX5143

µMAX

GND

OUT

CLR

GND

RFB

INV

OUT

PART T EM P. RA N G E PIN - PAC K A GE IN L ( L SB )

M A X5 1 4 1E U A

M A X5 1 4 2E U B

M A X5 1 4 3E U A

M A X5 1 4 4E U B

-40°C to +85°C 8 µMAX ± 15 U nip ol ar

-40°C to +85°C 10 µMAX ± 15 Bi pol ar

-40°C to +85°C 8 µMAX ± 13 U nip ol ar

-40°C to +85°C 10 µMAX ± 13 Bi pol ar

SU PPL Y

R A NG E ( V)

O U TPU T SWING

Page 2

MAX5141–MAX5144

+3V/+5V, Serial-Input, Voltage-Output, 14-Bit DACs

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VDD= +3V (MAX5143/MAX5144) or +5V (MAX5141/MAX5142), V

REF

= +2.5V, TA= T

MIN

to T

MAX

, CL= 10pF, GND = 0, RL= ∞,

unless otherwise noted. Typical values are at T

= +25°C.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

VDDto GND..............................................................-0.3V to +6V

CS, SCLK, DIN, CLR to GND ...................................-0.3V to +6V

REF to GND................................................-0.3V to (V

+ 0.3V)

OUT, INV to GND .....................................................-0.3V to V

RFB to INV ...................................................................-6V to +6V

RFB to GND.................................................................-6V to +6V

Maximum Current into Any Pin............................................50mA

Continuous Power Dissipation (T

= +70°C)

8-Pin µMAX (derate 4.5mW/°C above +70°C)...............362mW

10-Pin µMAX (derate 5.6mW/°C above +70°C).............444mW

Operating Temperature Ranges

MAX514_ EUA ...................................................-40°C to +85°C

MAX514_ EUB ...................................................-40°C to +85°C

Storage Temperature Range .............................-65°C to +150°C

Maximum Die Temperature..............................................+150°C

Lead Temperature (soldering, 10s) .................................+300°C

REFERENCE INPUT

STATIC PERFORMANCE—ANALOG SECTION

Integral Nonlinearity INL LSB±0.5 ±1MAX514_

+4.5V ≤ VDD≤ +5.5V (MAX5141/MAX5142) ±1

Power-Supply Rejection

+2.7V ≤ VDD≤ +3.3V (MAX5143/MAX5144) ±1

LSB

Ratio error

LSB

RFB/R

INV

Digital Feedthrough nV-s0.2

Code = 0000 hex; CS = VDD; SCLK, DIN = 0V to V

levels

DAC Glitch Impulse nV-s7Major-carry transition

Output Settling Time µs1

To ±1/2LSB of FS

DYNAMIC PERFORMANCE—ANALOG SECTION

Voltage-Output Slew Rate SR V/µs15(Note 5)

Bipolar Zero Offset Error

Guaranteed monotonic

LSBZSE

PARAMETER SYMBOL MIN TYP MAX UNITS

Zero-Code Offset Error ±2

Differential Nonlinearity DNL LSB

Zero-Code Tempco ZS

±0.05 ppm/°C

±10Gain Error (Note 1) LSB

Gain-Error Tempco ±0.1 ppm/°C

Resolution N 14 Bits

±0.5 ±1

6.2 kΩDAC Output Resistance R

OUT

Bipolar Resistor Matching

±0.03

±20

Bipolar Zero Tempco BZS

±0.5 ppm/°C

PSR

Reference Input Range V

REF

2.0 V

Reference Input Resistance (Note 4)

REF

kΩ

CONDITIONS

(Note 2)

(Note 3)

Unipolar mode

Bipolar mode

STATIC PERFORMANCE—ANALOG SECTION

Page 3

MAX5141–MAX5144

+3V/+5V, Serial-Input,

Voltage-Output, 14-Bit DACs

_______________________________________________________________________________________ 3

TIMING CHARACTERISTICS

(VDD= +2.7V to +3.3V (MAX5143/MAX5144), VDD= +4.5V to +5.5V (MAX5141/MAX5142), V

REF

= +2.5V, GND = 0, CMOS inputs,

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Figure 1)

Note 1: Gain error tested at V

REF

= +2.0V, +2.5V, and +3.0V (MAX5143/MAX5144) or V

REF

= +2.0V, +2.5V, +3.0V, and +5.0V

(MAX5141/MAX5142).

Note 2: R

OUT

tolerance is typically ±20%.

Note 3: Min/max range guaranteed by gain-error test. Operation outside min/max limits will result in degraded performance. Note 4: Reference input resistance is code dependent, minimum at 2155 hex in unipolar mode, 1155 hex in bipolar mode. Note 5: Slew-rate value is measured from 10% to 90%. Note 6: Guaranteed by design. Not production tested. Note 7: Guaranteed by power-supply rejection test and Timing Characteristics.

Code = 3FFF hex

All digital inputs at VDDor GND

MAX5143/MAX5144

Code = 0000 hex, V

REF

= 1V

P-P

at 100kHz

Code = 0000 hex

Code = 3FFF hex

(Note 6)

CONDITIONS

0.36

PDPower Dissipation

mA0.12 0.20I

Positive Supply Current

2.7 3.6

Positive Supply Range (Note 7)

V0.15V

Hysteresis Voltage

pF310C

Input Capacitance

P-P

MHz1BWReference -3dB Bandwidth

µA±1I

Input Current

V0.8V

Input Low Voltage

V2.4V

Input High Voltage

Reference Feedthrough

dB92SNRSignal-to-Noise Ratio

170

INREF

Reference Input Capacitance

UNITSMIN TYP MAXSYMBOLPARAMETER

(Note 6)

CONDITIONS

µs20

VDDHigh to CS Low (Power-Up Delay)

ns20t

SCLK Pulse Width Low

ns20t

MHz25f

CLK

SCLK Frequency

SCLK Pulse Width High

ns20t

CLW

CLR Pulse Width Low

ns0t

DIN to SCLK High Hold

ns15t

DIN to SCLK High Setup

ns15t

CSS0

CS Low to SCLK High Setup

ns15t

CSS1

CS High to SCLK High Setup

ns35t

CSH0

SCLK High to CS Low Hold

ns20t

CSH1

SCLK High to CS High Hold

UNITSMIN TYP MAXSYMBOLPARAMETER

ELECTRICAL CHARACTERISTICS (continued)

(VDD= +3V (MAX5143/MAX5144) or +5V (MAX5141/MAX5142), V

REF

= +2.5V, TA= T

MIN

to T

MAX

, CL= 10pF, GND = 0, RL = ∞,

unless otherwise noted. Typical values are at T

= +25°C.)

0.60MAX5141/MAX5142

MAX5143/MAX5144

MAX5141/MAX5142 4.5 5.5

DYNAMIC PERFORMANCE—REFERENCE SECTION

STATIC PERFORMANCE—DIGITAL INPUTS

POWER SUPPLY

Page 4

MAX5141–MAX5144

+3V/+5V, Serial-Input, Voltage-Output, 14-Bit DACs

4 _______________________________________________________________________________________

Typical Operating Characteristics

(VDD= +3V (MAX5143/MAX5144) or +5V (MAX5141/MAX5142), V

REF

= +2.5V, TA= T

MIN

to T

MAX

, GND = 0, RL= ∞, unless otherwise

noted. Typical values are at T

= +25°C.)

0.050

0.025

0.100

0.075

0.125

0.150

-40 10-15 35 60 85

SUPPLY CURRENT vs. TEMPERATURE

MAX5141/44 toc01

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

VDD = +5V

VDD = +3V

0.05

0.07

0.06

0.09

0.08

0.11

0.10

0.12

0 1.0 1.50.5 2.0 2.5 3.0 3.5 4.5 5.0

SUPPLY CURRENT

vs. REFERENCE VOLTAGE

MAX5141/44 toc02

REFERENCE VOLTAGE (V)

SUPPLY CURRENT (mA)

4.0

VDD = +5V

0 1.0 1.50.5 2.0 2.5 3.0

0.05

0.07

0.06

0.09

0.08

0.11

0.10

0.12

SUPPLY CURRENT

vs. REFERENCE VOLTAGE

MAX5141/44 toc03

REFERENCE VOLTAGE (V)

SUPPLY CURRENT (mA)

VDD = +3V

-0.2

-0.1

0.2

0.1

0.3

0.4

-40 10-15 35 60 85

ZERO-CODE OFFSET ERROR

vs. TEMPERATURE

MAX5141 toc04

TEMPERATURE (°C)

OFFSET ERROR (LSB)

-0.30

-0.20

-0.25

-0.10

-0.15

-0.05

-40 10-15 35 60 85

GAIN ERROR vs. TEMPERATURE

MAX5141 toc07

TEMPERATURE (°C)

GAIN ERROR (LSB)

0.5

0.4

0.3

0.2

0.1

0.0

-0.1

-0.2

-0.3

-0.4

-0.5 0 2.50k 5.00k 7.50k 10.00k 12.50k 15.00k

DIFFERENTIAL NONLINEARITY vs. CODE

MAX5141 toc08

DNL (LSB)

CODE

1.0

0.8

0.6

0.4

0.2

0.0

-0.2

-0.4

-0.6

-0.8

-1.0

CODE

0 2.50k 5.00k 7.50k 10.00k 12.50k 15.00k

INTEGRAL NONLINEARITY vs. CODE

MAX5141 toc09

INL (LSB)

-0.4

-0.2

0.4

0.2

0.6

0.8

-40 10-15 35 60 85

INTEGRAL NONLINEARITY

vs. TEMPERATURE

MAX5141 toc05

TEMPERATURE (°C)

INL (LSB)

+INL

-INL

-0.4

-0.2

-0.3

-0.1

0.1

0.2

-40 10-15 35 60 85

DIFFERENTIAL NONLINEARITY

vs. TEMPERATURE

MAX5141 toc06

TEMPERATURE (°C)

DNL (LSB)

+DNL

-DNL

Page 5

MAX5141–MAX5144

+3V/+5V, Serial-Input,

Voltage-Output, 14-Bit DACs

_______________________________________________________________________________________ 5

Typical Operating Characteristics (continued)

(VDD= +3V (MAX5143/MAX5144) or +5V (MAX5141/MAX5142), V

REF

= +2.5V, TA= T

MIN

to T

MAX

, GND = 0, RL= ∞, unless otherwise

noted. Typical values are at T

= +25°C.)

UNIPOLAR POWER-ON GLITCH

(REF = V

)

MAX5141/44 toc17

50ms/div

2V/div

OUT

10mV/div

REFERENCE CURRENT

vs. DIGITAL INPUT CODE

140

FULL-SCALE STEP RESPONSE

(FALLING)

MAX5141/44 toc11

FULL-SCALE STEP RESPONSE

(RISING)

MAX5141/44 toc12

120

100

REFERENCE CURRENT (µA)

0 5k 10k 15k 20k

INPUT CODE

MAJOR-CARRY GLITCH

(RISING)

200ns/div

MAX5141/44 toc13

CL = 20pF

MAX5141 toc10

CS 1V/div

OUT

20mV/div

400ns/div

MAJOR-CARRY GLITCH

(FALLING)

200ns/div

CL = 20pF

MAX5141/44 toc14

CL = 20pF

CS 2V/div

OUT

2V/div

CS 1V/div

OUT

20mV/div

400ns/div

DIGITAL FEEDTHROUGH

50ns/div

CL = 20pF

MAX5141/44 toc15

CS 2V/div

OUT

2V/div

OUT

10mV/div

INTEGRAL NONLINEARITY vs.

0.70

0.65

0.60

0.55

INL (LSB)

0.50

0.45

0.40

2.0 3.0 3.52.5 4.0 4.5 5.0

REFERENCE VOLTAGE

REFERENCE VOLTAGE (V)

MAX5141 toc16

Page 6

MAX5141–MAX5144

+3V/+5V, Serial-Input, Voltage-Output, 14-Bit DACs

6 _______________________________________________________________________________________

Pin Descriptions

Figure 1. Timing Diagram

MAX5141 MAX5143

MAX5142 MAX5144

NAME FUNCTION

1 1 REF Voltage Reference Input 22CS Chip-Select Input

3 3 SCLK Serial Clock Input. Duty cycle must be between 40% and 60%.

4 4 DIN Serial Data Input

55CLR

Clear Input. Logic low asynchronously clears the DAC to code 0 (MAX5141/MAX5143) or code 8192 (MAX5142/MAX5144).

6 6 OUT DAC Output Voltage

— 7 INV

Junction of Internal Scaling Resistors. Connect to external op amp’s inverting input in bipolar mode.

— 8 RFB Feedback Resistor. Connect to external op amp’s output in bipolar mode.

79VDDSupply Voltage. Use +3V for MAX5143/MAX5144 and +5V for MAX5141/MAX5142.

8 10 GND Ground

SCLK

DIN

CSHO

CSSO

D13 D12

CSH1

CSS1

LDACS

Page 7

MAX5141–MAX5144

+3V/+5V, Serial-Input,

Voltage-Output, 14-Bit DACs

_______________________________________________________________________________________ 7

Detailed Description

The MAX5141–MAX5144 voltage-output, 14-bit digitalto-analog converters (DACs) offer full 14-bit performance with less than 1LSB integral linearity error and less than 1LSB differential linearity error, thus ensuring monotonic performance. Serial data transfer minimizes the number of package pins required.

The MAX5141–MAX5144 are composed of two matched DAC sections, with a 10-bit inverted R-2R DAC forming the ten LSBs and the four MSBs derived from 15 identically matched resistors. This architecture allows the lowest glitch energy to be transferred to the DAC output on major-carry transitions. It also lowers the DAC output impedance by a factor of eight compared

Figure 2b. Typical Operating Circuit—Bipolar Output

Figure 2a. Typical Operating Circuit—Unipolar Output

+2.5V

MAX6166

+3V/+5V

0.1µF

MC68XXXX

DIN

SCLK

CLR

(GND)

PCS0

MOSI

SCLK

IC1

MAX6166

+3V/+5V

0.1µF

DIN

SCLK

CLR

MC68XXXX

PCS0

MOSI

SCLK

IC1

(GND)

REF

1µF

0.1µF

REF

MAX5141 MAX5142 MAX5143 MAX5144

+2.5V

MAX5142 MAX5144

GND

1µF

0.1µF

GND

INV

MAX495

OUT

RFB

INV

OUT

EXTERNAL OP AMP

+5V

MAX400

EXTERNAL OP AMP

-5V

UNIPOLAR OUT

BIPOLAR OUT

Page 8

MAX5141–MAX5144

+3V/+5V, Serial-Input, Voltage-Output, 14-Bit DACs

8 _______________________________________________________________________________________

to a standard R-2R ladder, allowing unbuffered operation in medium-load applications.

The MAX5142/MAX5144 provide matched bipolar offset resistors, which connect to an external op amp for bipolar output swings (Figure 2b).

Digital Interface

The MAX5141–MAX5144 digital interface is a standard 3-wire connection compatible with SPI/QSPI/ MICROWIRE interfaces. The chip-select input (CS) frames the serial data loading at the data-input pin (DIN). Immediately following CS’s high-to-low transition, the data is shifted synchronously and latched into the input register on the rising edge of the serial clock input (SCLK). After 16 bits (14 data bits, plus two subbits set to zero) have been loaded into the serial input register, it transfers its contents to the DAC latch on CS’s low-tohigh transition (Figure 3). Note that if CS is not kept low during the entire 16 SCLK cycles, data will be corrupted. In this case, reload the DAC latch with a new 16-bit word.

Clearing the DAC

A 20ns (min) logic low pulse on CLR asynchronously clears the DAC buffer to code 0 in the MAX5141/ MAX5143 and to code 8192 in the MAX5142/MAX5144.

External Reference

The MAX5141–MAX5144 operate with external voltage references from +2V to VDD. The reference voltage determines the DAC’s full-scale output voltage.

Power-On Reset

The power-on reset circuit sets the output of the MAX5141/MAX5143 to code 0 and the output of the MAX5142/MAX5144 to code 8192 when VDDis first

applied. This ensures that unwanted DAC output voltages will not occur immediately following a system power-up, such as after a loss of power.

Applications Information

Reference and Ground Inputs

The MAX5141–MAX5144 operate with external voltage references from +2V to VDD, and maintain 14-bit performance if certain guidelines are followed when selecting and applying the reference. Ideally, the reference’s temperature coefficient should be less than 0.5ppm/°C to maintain 14-bit accuracy to within 1LSB over the -40°C to +85°C extended temperature range. Since this converter is designed as an inverted R-2R voltage-mode DAC, the input resistance seen by the voltage reference is code dependent. In unipolar mode, the worst-case input-resistance variation is from 11.5kΩ (at code 2155 hex) to 200kΩ (at code 0000 hex). The maximum change in load current for a +2.5V reference is +2.5V / 11.5kΩ = 217µA; therefore, the required load regulation is 28ppm/mA for a maximum error of 0.1LSB. This implies a reference output impedance of less than 72mΩ. In addition, the signal-path impedance from the voltage reference to the reference input must be kept low because it contributes directly to the load-regulation error.

The requirement for a low-impedance voltage reference is met with capacitor bypassing at the reference inputs and ground. A 0.1µF ceramic capacitor with short leads between REF and GND provides high-frequency bypassing. A surface-mount ceramic chip capacitor is preferred because it has the lowest inductance. An additional 1µF between REF and GND provides low-frequency bypassing. A low-ESR tantalum, film, or organic semiconductor capacitor works well. Leaded capacitors are acceptable because impedance is not as criti-

Figure 3. MAX5141–MAX5144 3-Wire Interface Timing Diagram

DAC

UPDATED

SCLK

SUB-BITS

DIN

D13 D6 D5 D4 D3 D2 D1 D0 S1 S0

D12 D11 D10 D9 D8 D7

MSB LSB

Page 9

MAX5141–MAX5144

+3V/+5V, Serial-Input,

Voltage-Output, 14-Bit DACs

_______________________________________________________________________________________ 9

cal at lower frequencies. The circuit can benefit from even larger bypassing capacitors, depending on the stability of the external reference with capacitive loading.

Unbuffered Operation

Unbuffered operation reduces power consumption as well as offset error contributed by the external output buffer. The R-2R DAC output is available directly at OUT, allowing 14-bit performance from +V

REF

to GND without degradation at zero scale. The DAC’s output impedance is also low enough to drive medium loads (RL> 60kΩ) without degradation of INL or DNL; only the gain error is increased by externally loading the DAC output.

External Output Buffer Amplifier

The requirements on the external output buffer amplifier change whether the DAC is used in unipolar or bipolar operational mode. In unipolar mode, the output amplifier is used in a voltage-follower connection. In bipolar mode (MAX5142/MAX5144 only), the amplifier operates with the internal scaling resistors (Figure 2b). In each mode, the DAC’s output resistance is constant and is independent of input code; however, the output amplifier’s input impedance should still be as high as possible to minimize gain errors. The DAC’s output capacitance is also independent of input code, thus simplifying stability requirements on the external amplifier.

In bipolar mode, a precision amplifier operating with dual power supplies (such as the MAX400) provides the ±V

REF

output range. In single-supply applications, precision amplifiers with input common-mode ranges including GND are available; however, their output swings do not normally include the negative rail (GND) without significant degradation of performance. A single-supply op amp, such as the MAX495, is suitable if the application does not use codes near zero.

Since the LSBs for a 14-bit DAC are extremely small (152.6µV for V

REF

= +2.5V), pay close attention to the external amplifier’s input specification. The input offset voltage can degrade the zero-scale error and might require an output offset trim to maintain full accuracy if the offset voltage is greater than 1/2LSB. Similarly, the input bias current multiplied by the DAC output resistance (typically 6.25kΩ) contributes to zero-scale error. Temperature effects also must be taken into consideration. Over the -40°C to +85°C extended temperature range, the offset voltage temperature coefficient (referenced to +25°C) must be less than 0.95µV/°C to add less than 1/2LSB of zero-scale error. The external amplifier’s input resistance forms a resistive divider with

the DAC output resistance, which results in a gain error. To contribute less than 1/2LSB of gain error, the input resistance typically must be greater than:

The settling time is affected by the buffer input capacitance, the DAC’s output capacitance, and PC board capacitance. The typical DAC output voltage settling time is 1µs for a full-scale step. Settling time can be significantly less for smaller step changes. Assuming a single time-constant exponential settling response, a full-scale step takes 10.4 time constants to settle to within 1/2LSB of the final output voltage. The time constant is equal to the DAC output resistance multiplied by the total output capacitance. The DAC output capacitance is typically 10pF. Any additional output capacitance increases the settling time.

The external buffer amplifier’s gain-bandwidth product is important because it increases the settling time by adding another time constant to the output response. The effective time constant of two cascaded systems, each with a single time-constant response, is approximately the root square sum of the two time constants. The DAC output’s time constant is 1µs / 10.4 = 96ns, ignoring the effect of additional capacitance. If the time constant of an external amplifier with 1MHz bandwidth is 1 / 2π (1MHz) = 159ns, then the effective time constant of the combined system is:

This suggests that the settling time to within 1/2LSB of the final output voltage, including the external buffer amplifier, will be approximately 10.4

186ns = 1.93µs.

Digital Inputs and Interface Logic

The digital interface for the 14-bit DAC is based on a 3-wire standard that is compatible with SPI, QSPI, and MICROWIRE interfaces. The three digital inputs (CS, DIN, and SCLK) load the digital input data serially into the DAC.

A 20ns (min) logic low pulse to CLR clears the data in the DAC buffer.

All of the digital inputs include Schmitt-trigger buffers to accept slow-transition interfaces. This means that optocouplers can interface directly to the MAX5141– MAX5144 without additional external logic. The digital inputs are compatible with TTL/CMOS-logic levels.

96ns 159ns 186ns

()

 



 



6.25k MΩΩ ×=2 205

Page 10

MAX5141–MAX5144

+3V/+5V, Serial-Input, Voltage-Output, 14-Bit DACs

10 ______________________________________________________________________________________

Unipolar Configuration

Figure 2a shows the MAX5141–MAX5144 configured for unipolar operation with an external op amp. The op amp is set for unity gain, and Table 1 lists the codes for this circuit. Bipolar MAX5142/MAX5144 can also be used in unipolar configuration by connecting RFB and INV to REF. This allows the DAC to power up to midscale.

Bipolar Configuration

Figure 2b shows the MAX5141–MAX5144 configured for bipolar operation with an external op amp. The op amp is set for unity gain with an offset of -1/2V

REF

. Table 2 shows the offset binary codes for this circuit (less than 0.25 inches).

Power-Supply Bypassing and

Ground Management

Bypass VDDwith a 0.1µF ceramic capacitor connected between V

and GND. Mount the capacitor with short

leads close to the device (less than 0.25 inches).

Table 1. Unipolar Code Table

Table 2. Bipolar Code Table

REF

(1 / 16,384)

0000 0000 0000 01

REF

(8192 / 16,384) =

REF

1000 0000 0000 00

REF

(16,383 / 16,384)

1111 1111 1111 11

ANALOG OUTPUT, V

OUT

MSB LSB

DAC LATCH CONTENTS

-V

REF

(8192 / 8192) = -V

REF

0000 0000 0000 00

-V

REF

(1 / 8192)

0111 1111 1111 11

0V1000 0000 0000 00

REF

(1 / 8192)

1000 0000 0000 01

REF

(8191 / 8192)

1111 1111 1111 11

ANALOG OUTPUT, V

OUT

MSB LSB

DAC LATCH CONTENTS

Chip Information

TRANSISTOR COUNT: 2800

PROCESS: BiCMOS

Functional Diagrams

REF

SCLK

DIN

CLR

MAX5141 MAX5143

14-BIT DAC

CONTROL

LOGIC

14-BIT DATA LATCH

SERIAL INPUT REGISTER

GND

OUT

SCLK

REF

DIN

CLR

MAX5142 MAX5144

14-BIT DAC

CONTROL

LOGIC

14-BIT DATA LATCH

SERIAL INPUT REGISTER

GND

RFB INV

OUT

Page 11

MAX5141-MAX5144

+3V/+5V, Serial-Input,

Voltage-Output, 14-Bit DACs

______________________________________________________________________________________ 11

________________________________________________________Package Information

8LUMAXD.EPS

Page 12

MAX5141–MAX5144

+3V/+5V, Serial-Input, Voltage-Output, 14-Bit DACs

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 _____________________12

Package Information (continued)

MAX5141–MAX5144

10LUMAX.EPS