MAXIM MAX1491, MAX1493, MAX1495 Technical data

General Description

The MAX1491/MAX1493/MAX1495 low-power, 3.5- and

4.5-digit, analog-to-digital converters (ADCs) with inte­grated liquid crystal display (LCD) drivers operate from a
single 2.7V to 5.25V power supply. They include an inter­nal reference, a high-accuracy on-chip oscillator, and a
triplexed LCD driver. An internal charge pump generates
the negative supply needed to power the integrated input
buffer for single supply operation. The ADC is config­urable for either a ±2V or ±200mV input range and it out­puts its conversion results to an LCD. The MAX1491 is a

3.5-digit (±1,999 count) device, and the MAX1493/
MAX1495 are 4.5-digit (±19,999 count) devices.

The MAX1491/MAX1493/MAX1495 do not require exter­nal-precision integrating or auto-zero capacitors, crys­tal oscillators, charge pumps or other circuitry required
with dual slope ADCs (commonly used in panel meter
circuits). These devices also feature on-chip buffers for
the differential signal and reference inputs, allowing
direct interface with high-impedance signal sources. In
addition, the MAX1491/MAX1493/MAX1495 use contin­uous internal offset calibration, and offer >100dB rejec­tion of 50Hz and 60Hz line noise. The MAX1493/
MAX1495 perform enhanced offset calibration at
power-up. The MAX1495 also performs enhanced cali­bration on demand. Other features include data hold
and peak hold, and a user programmable low-battery
monitor.

The MAX1493/MAX1495 come in a 32-pin 7mm ✕ 7mm
TQFP package, and the MAX1491 comes in 28-pin
SSOP and 28-pin DIP packages. All devices in this fam­ily operate over the 0°C to +70°C commercial tempera­ture range.

Applications

Digital Panel Meters

Hand-Held Meters

Digital Voltmeters

Digital Multimeters

Features

♦ High Resolution

MAX1495: 4.5 Digits (±19,999 Count)
MAX1493: 4.5 Digits (±19,999 Count)
MAX1491: 3.5 Digits (±1999 Count)

♦ Sigma-Delta ADC Architecture

No Integrating Capacitors Required
No Autozeroing Capacitors Required
>100dB of Simultaneous 50Hz and 60Hz Rejection

♦ Operate from a Single 2.7V or 5.25V Supply

♦ Selectable Input Range of ±200mV or ±2V

♦ Selectable Voltage Reference: Internal 2.048V or

External

♦ Internal High-Accuracy Oscillator Needs No

External Components

♦ Automatic Offset Calibration

♦ Low Power: Maximum 980µA Operating Current

♦ Small 32-Pin 7mm

✕ 7mm TQFP Package (4.5

Digits), 28-Pin SSOP Package (3.5 Digits), and 28­Pin DIP Package (3.5 Digits)

♦ Triplexed LCD Driver

♦ Evaluation Kit Available (Order MAX1494EVKIT)

MAX1491/MAX1493/MAX1495

3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers

________________________________________________________________ Maxim Integrated Products 1

Pin Configurations

Ordering Information

19-3053; Rev 0; 10/03

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 continued at end of data sheet.

EVALUATION KIT

AVAILABLE

*Future product—contact factory for availability.

查询MAX1491供应商

PART

MAX1491CAI* 0°C to +70°C 28 SSOP 3.5

MAX1491CNI 0°C to +70°C 28 DIP 3.5

MAX1493CCJ 0°C to +70°C 32 TQFP 4.5
MAX1495CCJ* 0°C to +70°C 32 TQFP 4.5

TEMP

RANGE

PIN­PACKAGE

RESOLUTION

(DIGITS)

TOP VIEW

AIN+

AIN-

REF-

REF+

LOWBATT

RANGE

DVDDINTREF

GND

32 28

1AV

DD

2

3

4

5

6

7

8DPSET1

10

9

PEAK

DPSET2

NEG

V

293031

MAX1493
MAX1495

SEG1

HOLD

TQFP

13

DPON

SEG2

BP1

BP2

BP3

26

25

27

24 SEG13

SEG12

23

22

SEG11

21

SEG10

20

SEG9

19

SEG8

18

SEG7

17

SEG6

14

15

1611 12

SEG4

SEG3

SEG5

MAX1491/MAX1493/MAX1495

3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(AVDD= DVDD= +2.7V to +5.25V, GND = 0, V

REF+

- V

REF-

= 2.048V (external reference), C

NEG

= 0.1µF. All specifications are T

MIN

to T

MAX

, unless otherwise noted. Typical values are at +25°C, unless otherwise noted.)

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.

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

DV

DD

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

AIN+, AIN- to GND...............................V

NEG

to + (AVDD+ 0.3V)

REF+, REF- to GND..............................V

NEG

to + (AVDD+ 0.3V)

LOWBATT to GND ...................................-0.3V to (AV

DD

+ 0.3V)

INTREF, RANGE, DPSET1, DPSET2, PEAK,

HOLD to GND......................................-0.3V to (DV

DD

+ 0.3V)

DPON to GND..........................................-0.3V to (DV

DD

+ 0.3V)

V

NEG

to GND ...........................................-2.6V to (AVDD+ 0.3V)

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

Continuous Power Dissipation (T

A

= +70°C)

32-Pin TQFP (derate 20.7mW/°C above +70°C).....1652.9mW

28-Pin SSOP (derate 9.5mW/°C above +70°C) ...........762mW

28-Pin DIP (derate 14.3mW/°C above +70°C)........1142.9mW

Operating Temperature Range...............................0°C to +70°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-60°C to +150°C

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DC ACCURACY

Noise-Free Resolution

Integral Nonlinearity (Note 1) INL

Range Change Accuracy

Rollover Error

Output Noise 10 µV

Offset Error (Zero Input Reading) Offset VIN = 0 (Note 2) -0 +0 Reading

Gain Error (Note 3) -0.5 +0.5 %FSR

Offset Drift (Zero Reading Drift) VIN = 0 0.1 µV/°C
Gain Drift ±1 ppm/°C

INPUT CONVERSION RATE

Conversion Rate 5Hz

ANALOG INPUTS (AIN+, AIN-) (bypass to GND with 0.1µF or greater capacitors)

Normal Mode 50Hz and 60Hz
Rejection (Simultaneously)

Common-Mode 50Hz and 60Hz
Rejection (Simultaneously)

Common-Mode Rejection CMR At DC 100 dB

Input Leakage Current TA = +25°C10nA

Input Capacitance 10 pF

Dynamic Input Current (Note 5) -20 +20 nA

CMR

MAX1493/MAX1495 -19,999 +19,999

MAX1491 -1999 +1999

2.000V range ±1

200mV range ±1

(V

AIN+

(V

AIN+

V

AIN+

V

AIN-

Differential (Note 4)

Absolute GND referenced -2.2V +2.2V

50Hz and 60Hz ±2% 100 dB

For 50Hz ±2% and 60Hz ±2%,
R

SOURCE

- V

= 0.100V) on 200mV range /

AIN-

- V

= 0.100V) on 2.0V range

AIN-

- V

= full scale,

AIN-

- V

= full scale

AIN+

RANGE = GND -2.0 +2.0

RANGE = DV

< 10kΩ

DD

-0.2 +0.2AIN Input Voltage Range

Count

Count

10:1 Ratio

±1.0 Count

V

150 dB

P-P

MAX1491/MAX1493/MAX1495

3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(AVDD= DVDD= +2.7V to +5.25V, GND = 0, V

REF+

- V

REF-

= 2.048V (external reference), C

NEG

= 0.1µF. All specifications are T

MIN

to T

MAX

, unless otherwise noted. Typical values are at +25°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

LOW-BATTERY VOLTAGE MONITOR (LOWBATT)

LOWBATT Trip Threshold 2.048 V

LOWBATT Leakage Current 10 pA

Hysteresis 20 mV

INTERNAL REFERENCE (REF- = GND, INTREF = DVDD, bypass REF+ to GND with 4.7µF capacitors)

REF Output Voltage V

REF Output Short-Circuit Current TA = +25°C1mA

REF Output Temperature
Coefficient

Load Regulation

Line Regulation 50 µV/V

Noise Voltage

EXTERNAL REFERENCE (INTREF = GND, bypass REF+ and REF- to GND with 0.1µF or greater capacitors)

REF Input Voltage

Normal-Mode 50Hz and 60Hz
Rejection (Simultaneously)

Common-Mode 50Hz and 60Hz
Rejection (Simultaneously)

Common-Mode Rejection CMR At DC 100 dB

Input Leakage Current TA = +25°C10nA

Input Capacitance 10 pF

Dynamic Input Current (Note 5) -20 +20 nA

CHARGE PUMP

Output Voltage V

DIGITAL INPUTS (INTREF, RANGE, PEAK, HOLD, DPSET1, DPSET2, DPON)

Input Current I

Input Low Voltage V

Input High Voltage V

Input Hysteresis V

TC

CMR

REF

VREF

NEG

IN

INL

INH

HYS

AVDD = 5V, TA = +25°C 2.007 2.048 2.089 V

AVDD = 5V 40 ppm/°C

I

SOURCE

I

SINK

0.1Hz to 10Hz 25

10Hz to 10kHz 400

Differential (V

Absolute GND referenced -2.2 +2.2

50Hz and 60Hz ±2% 100 dB

For 50Hz ±2% and 60Hz ±2%,
R

SOURCE

VIN = 0 or DV

DVDD = 3.0V 200 mV

= 0µA to 300µA,

= 0µA to 30µA, TA = +25°C (Note 6)

- V

REF+

< 10kΩ

DD

) 2.048

REF-

6 mV/µA

150 dB

-2.6 -2.42 -2.3 V

-10 +10 µA

0.3 x

DV

DD

0.7 x

DV

DD

µVp-p

V

V

V

MAX1491/MAX1493/MAX1495

3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(AVDD= DVDD= +2.7V to +5.25V, GND = 0, V

REF+

- V

REF-

= 2.048V (external reference), C

NEG

= 0.1µF. All specifications are T

MIN

to T

MAX

, unless otherwise noted. Typical values are at +25°C, unless otherwise noted.)

Note 1: Integral nonlinearity is the derivation of the analog values at any code from its theoretical value after nulling the gain error

and offset error.

Note 2: Offset calibrated.
Note 3: Offset nulled.
Note 4: The input voltage range for the analog inputs is given with respect to the voltage on the negative input of the differential pair.
Note 5: For the range of V

AIN+

or V

AIN-

= -2.2V to +2.2V and V

REF+

or V

REF-

= -2.2V to +2.2V.

Note 6: External load must be constant during conversion for specified accuracy. Guaranteed specification of 2mV/mA is a result of

production test limitations.

Note 7: Measured at DC by changing the power-supply voltage from 2.7V to 5.25V and measuring its effect on the conversion error.

PSRR at 50Hz and 60Hz exceeds 120dB with filter notches of 10, 20, 30, 40, 50, or 60 Hz.

Note 8: Analog power-supply currents are measured with all digital inputs at either GND or DV

DD

. Digital power-supply currents

measured with all digital inputs at either GND or DV

DD

.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POWER SUPPLY

AVDD Voltage AV

DVDD Voltage DV

Power-Supply Rejection AV

Power-Supply Rejection DV

AVDD Current I

DVDD Current I

LCD DRIVER

RMS Segment-On Voltage

RMS Segment-Off Voltage

Display Multiplex Rate 107 Hz

LCD Data-Update Rate 2.5 Hz

DD

DD

DD

DD

PSRRA(Note 7) 80 dB

PSRRD(Note 7) 100 dB

AVDD

DVDD

(Note 8) 660 µA

DVDD = 5V 320

DVDD = 3.3V 180

2.70 5.25 V

2.70 5.25 V

1.92 x
DV

DD

1 / 3 x
DV

DD

µA

V

V

MAX1491/MAX1493/MAX1495

3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers

_______________________________________________________________________________________ 5

Typical Operating Characteristics

(AVDD= DVDD= 5V, GND = 0, REF+ = 2.048V, REF- = GND, RANGE = DVDD, TA= +25°C.)

MAX1493/MAX1495 (±200mV INPUT RANGE)

INL vs. DISPLAY COUNT

1.0

0.5

0

INL (COUNTS)

-0.5

-1.0

-20,000 20,000
DISPLAY COUNT

10,0000-10,000

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

700

600

ANALOG SUPPLY

500

400

300

SUPPLY CURRENT (µA)

DIGITAL SUPPLY

200

100

0

2.75 5.25
SUPPLY VOLTAGE (V)

4.754.253.753.25

MAX1491/3/5 toc01

MAX1491/3/5 toc04

MAX1493/MAX1495 (±2V INPUT RANGE)

INL vs. DISPLAY COUNT

1.0

0.5

0

INL (COUNTS)

-0.5

-1.0

-20,000 20,000
DISPLAY COUNT

10,0000-10,000

MAX1493/MAX1495

GAIN ERROR vs. SUPPLY VOLTAGE

0.08

0.06

0.04

0.02

0

-0.02

-0.04

GAIN ERROR (% FULL SCALE)

-0.06

-0.08

-0.10

2.75 5.25
SUPPLY VOLTAGE (V)

4.754.253.25 3.75

MAX1491/3/5 toc02

MAX1491/3/5 toc05

25

20

15

10

PERCENTAGE OF UNITS (%)

5

0

0

-0.01

-0.02

-0.03

-0.04

-0.05

-0.06

-0.07

GAIN ERROR (% FULL SCALE)

-0.08

-0.09

-0.10

NOISE DISTRIBUTION

MAX1491/3/5 toc03

-0.2
NOISE (COUNTS)

0.80.70.60.50.40.30.20.10-0.1

MAX1493/MAX1495

GAIN ERROR vs. TEMPERATURE

MAX1491/3/5 toc06

070

TEMPERATURE (°C)

605030 402010

MAX1491/MAX1493/MAX1495

3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(AVDD= DVDD= 5V, GND = 0, REF+ = 2.048V, REF- = GND, RANGE = DVDD, TA= +25°C.)

INTERNAL REFERENCE VOLTAGE

vs. TEMPERATURE

2.054

2.053

2.052

2.051

2.050

2.049

2.048

2.047

REFERENCE VOLTAGE (V)

2.046

2.045

2.044
070

TEMPERATURE (°C)

605040302010

2.050

2.049

MAX1491/3/5 toc07

2.048

2.047

2.046

REFERENCE VOLTAGE (V)

2.045

2.044

INTERNAL REFERENCE VOLTAGE

vs. ANALOG SUPPLY VOLTAGE

2.75 5.25
SUPPLY VOLTAGE (V)

CHARGE-PUMP OUTPUT VOLTAGE

V

-2.40

vs. ANALOG SUPPLY VOLTAGE

-2.42

-2.44

VOLTAGE (V)

-2.46

NEG

V

-2.48

-2.50

2.75 5.25
SUPPLY VOLTAGE (V)

4.754.253.753.25

MAX1491/3/5 toc10

2V/div

1V/div

STARTUP SCOPE SHOT

NEG

V

DD

V

NEG

C

= 0.1µF

NEG

20ms/div

SUPPLY CURRENT

vs. TEMPERATURE

700

600

MAX1491/3/5 toc08

4.754.253.753.25

ANALOG SUPPLY

500

400

300

SUPPLY CURRENT (µA)

200

100

DIGITAL SUPPLY

0

070

TEMPERATURE (°C)

MAX1491/3/5 toc09

605040302010

OFFSET ERROR

vs. COMMON-MODE VOLTAGE

0.20

0.15

MAX1491/3/5 toc11

0.10

0.05

0

-0.05

OFFSET ERROR (COUNTS)

-0.10

-0.15

-0.20

-2.0 2.0
COMMON-MODE VOLTAGE (V)

MAX1491/3/5 toc12

1.51.0-1.5 -1.0 -0.5 0 0.5

MAX1491/MAX1493/MAX1495

3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers

_______________________________________________________________________________________ 7

Pin Description

PIN

MAX1491

1 30 INTREF

231DV

3 32 GND Ground

41AV

5 2 AIN+

6 3 AIN-

7 4 REF-

8 5 REF+

9 6 LOWBATT Low Batter y Inp ut. W hen V

10 7 RANGE

11 8 DPSET1

12 9 DPSET2

13 10 PEAK

MAX1493
MAX1495

NAME FUNCTION

Internal Reference Logic Input. Connect to GND to select external reference mode. Connect
to DV

Digital Power Input. Connect DVDD to a 2.7V to 5.25V power supply. Bypass DVDD to GND

DD

with a 0.1µF and a 4.7µF capacitor.

Analog Power Input. Connect AVDD to a 2.7V to 5.25V power supply. Bypass AVDD to GND

DD

with a 0.1µF and a 4.7µF capacitor.

Positive Analog Input. Positive side of fully differential analog input. Bypass A
a 0.1µF or greater capacitor.

Negative Analog Input. Negative side of fully differential analog input. Bypass A
with a 0.1µF or greater capacitor.

Negative Reference Input. For internal reference operation, connect REF- to GND. For
external reference operation, bypass REF- to GND with a 0.1µF capacitor and set V

-2.2V to +2.2V, provided V

Positive Reference Input. For internal reference operation, connect a 4.7µF capacitor from
REF+ to GND. For external reference operation, bypass REF+ to GND with a 0.1µF capacitor
and set V

Range Logic Input. RANGE controls the fully differential analog input range. Connect to GND
for the ±2V input range. Connect to DV

Decimal Point Logic Input 1. Controls the decimal point of the LCD. See the Decimal Point
Control section.

Decimal Point Logic Input 2. Controls the decimal point of the LCD. See the Decimal Point
Control section.

Peak Logic Input. Connect to DV
GND to disable the peak function.

to select the internal reference mode.

DD

from -2.2V to +2.2V, provided V

REF+

> V

REF+

LOWB ATT

to GND with

IN+

to GND

IN-

.

REF-

> V

REF+

< 2.048V ( typ ) , the LO WBATT sym b ol on the LC D tur ns on.

for the ±200mV input range.

DD

to display the highest ADC value on the LCD. Connect to

DD

REF-

.

REF-

from

Hold Logic Input. Connect to DV

14 11 HOLD

15 12 SEG1 LCD Segment 1 Driver

16 13 SEG2 LCD Segment 2 Driver

17 14 SEG3 LCD Segment 3 Driver

18 15 SEG4 LCD Segment 4 Driver

19 16 SEG5 LCD Segment 5 Driver

20 17 SEG6 LCD Segment 6 Driver

GND to update the LCD at a rate of 2.5Hz and disable the hold function. For the MAX1495,
placing the device into hold mode initiates an enhanced offset calibration. Assert HOLD high
for a minimum of 2s to ensure the completion of enhanced offset calibration.

to hold the current ADC value on the LCD. Connect to

DD

MAX1491/MAX1493/MAX1495

3.5- and 4.5-Digit, Single-Chip
ADCs with LCD Drivers

8 _______________________________________________________________________________________

Pin Description (continued)

Figure 1. MAX1493/MAX1495 Functional Diagram

PIN

MAX1491

MAX1493
MAX1495

NAME FUNCTION

21 18 SEG7 LCD Segment 7 Driver

22 19 SEG8 LCD Segment 8 Driver

23 20 SEG9 LCD Segment 9 Driver

24 21 SEG10 LCD Segment 10 Driver

25 25 BP3 LCD Backplane 3 Driver

26 26 BP2 LCD Backplane 2 Driver

27 27 BP1 LCD Backplane 1 Driver

28 29 V

NEG

-2.5V Charge-Pump Voltage Output. Connect a 0.1µF capacitor from V

— 22 SEG11 LCD Segment 11 Driver

— 23 SEG12 LCD Segment 12 Driver

— 24 SEG13 LCD Segment 13 Driver

— 28 DPON

AV

DD

MAX1493
MAX1495

AIN+

AIN-

REF+

+2.5V

INPUT

BUFFERS

Decimal Point Enable Input. Controls the decimal point of the LCD. See the Decimal Point
Control section. Connect to DV

DV

DD

DPON HOLD

DPSET1 DPSET2

CONTROL

ADC

to enable the decimal point.

DD

BINARY-TO-BCD

to GND.

NEG

INTREF

PEAK

RANGE

SEG1

CONVERTERS

AND

LCD DRIVERS

SEG13
BP1
BP2
BP3

A = 1.22

OSCILLATOR/

CLOCK

+2.5V

CHARGE

PUMP

NEG

-2.5V

TO

CONTROL

LOWBATTV

REF-

-2.5V

2.048V

BANDGAP

REFERENCE

GND