_______________General Description

The MAX1248/MAX1249 10-bit data-acquisition sys-
tems combine a 4-channel multiplexer, high-bandwidth
track/hold, and serial interface with high conversion
speed and low power consumption. They operate from
a single +2.7V to +5.25V supply, and their analog
inputs are software configurable for unipolar/bipolar
and single-ended/differential operation.
The 4-wire serial interface connects directly to SPITM/
QSPITM and MICROWIRETM devices without external
logic. A serial strobe output allows direct connection
to TMS320-family digital signal processors. The
MAX1248/MAX1249 use either the internal clock or an
external serial-interface clock to perform successive-
approximation analog-to-digital conversions.
The MAX1248 has an internal 2.5V reference, while the
MAX1249 requires an external reference. Both parts
have a reference-buffer amplifier with a ±1.5% voltage
adjustment range.
These devices provide a hard-wired SHDN pin and a
software-selectable power-down, and can be pro-
grammed to automatically shut down at the end of a
conversion. Accessing the serial interface automatically
powers up the MAX1248/MAX1249, and the quick
turn-on time allows them to be shut down between all
conversions. This technique can cut supply current to
under 60µA at reduced sampling rates.
The MAX1248/MAX1249 are available in a 16-pin DIP
and a very small QSOP that occupies the same board
area as an 8-pin SO.
For 8-channel versions of these devices, see the
MAX148/MAX149 data sheet.

________________________Applications

Portable Data Logging

Data Acquisition

Medical Instruments

Battery-Powered Instruments

Pen Digitizers

System Supervision

____________________________Features

4-Channel Single-Ended or 2-Channel
Differential Inputs

Single +2.7V to +5.25V Operation

Internal 2.5V Reference (MAX1248)

Low Power: 1.2mA (133ksps, +3V supply)

54µA (1ksps, +3V supply)
1µA (power-down mode)

SPI/QSPI/MICROWIRE/TMS320-Compatible
4-Wire Serial Interface

Software-Configurable Unipolar or Bipolar Inputs

16-Pin QSOP Package (same area as 8-pin SO)

MAX1248/MAX1249

+2.7V to +5.25V, Low-Power, 4-Channel,

Serial 10-Bit ADCs in QSOP-16

________________________________________________________________

Maxim Integrated Products

19-1072; Rev 2; 5/98

PART

MAX1248

ACPE

MAX1248BCPE

MAX1248ACEE

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

16 Plastic DIP

16 QSOP

_____________Ordering Information

Ordering Information continued at end of data sheet.

Contact factory for availability of alternate surface-mount
packages.

Pin Configuration appears at end of data sheet.

MAX1248BCEE

0°C to +70°C

16 QSOP

INL

(LSB)

±1/2

±1

±1/2

±1

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

I/O

SCK (SK)

MOSI (SO)

MISO (SI)

SHDN

SSTRB

DOUT

DIN

SCLK

COM

AGND

DGND

CH3

4.7

0.01

0.1

CH0

0V TO

+2.5V

ANALOG

INPUTS

MAX1248

CPU

+3V

VREF

REFADJ

__________Typical Operating Circuit

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.

MAX1248/MAX1249

+2.7V to +5.25V, Low-Power, 4-Channel,
Serial 10-Bit ADCs in QSOP-16

_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

= +2.7V to +5.25V; COM = 0V; f

SCLK

= 2.0MHz; external clock (50% duty cycle); 15 clocks/conversion cycle (133ksps);

MAX1248--4.7µF capacitor at VREF pin; MAX1249--external reference, VREF = 2.500V applied to VREF pin; T

= T

MIN

to T

MAX

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.

to AGND, DGND .............................................. -0.3V to +6V

AGND to DGND.................................................... -0.3V to +0.3V
CH0CH3, COM to AGND, DGND ............ -0.3V to (V

+ 0.3V)

VREF to AGND........................................... -0.3V to (V

+ 0.3V)

Digital Inputs to DGND............................................ -0.3V to +6V
Digital Outputs to DGND ........................... -0.3V to (V

+ 0.3V)

Digital Output Sink Current .................................................25mA
Continuous Power Dissipation (T

= +70°C)

Plastic DIP (derate 10.53mW/°C above +70°C) ......... 842mW

QSOP (derate 8.30mW/°C above +70°C) ................... 667mW
CERDIP (derate 10.00mW/°C above +70°C) .............. 800mW

Operating Temperature Ranges

MAX1248_C_E/MAX1249_C_E .......................... 0°C to +70°C
MAX1248_E_E/MAX1249_E_E........................ -40°C to +85°C
MAX1248_MJE/MAX1249_MJE .................... -55°C to +125°C

Storage Temperature Range ............................ -60°C to +150°C
Lead Temperature (soldering, 10sec) ............................ +300°C

µs

CONV

Conversion Time (Note 5)

5.5

7.5

MHz

1.0

Full-Power Bandwidth

MHz

2.25

Small-Signal Bandwidth

-75

Channel-to-Channel Crosstalk

SFDR

Spurious-Free Dynamic Range

-70

THD

Total Harmonic Distortion

SINAD

Signal-to-Noise + Distortion Ratio

LSB

±0.05

Channel-to-Channel Offset
Matching

ppm/°C

±0.25

Gain Temperature Coefficient

±0.5

Bits

Resolution

±1

Offset Error

LSB

±1.0

INL

Relative Accuracy (Note 2)

LSB

±1

DNL

±1

LSB

±2

UNITS

MIN

TYP

MAX

SYMBOL

PARAMETER

External clock = 2MHz, 12 clocks/conversion

Internal clock, SHDN = V

Internal clock, SHDN = FLOAT

MAX124_A

-3dB rolloff

65kHz, 2.500Vp-p (Note 4)

Up to the 5th harmonic

MAX124_A

MAX124_B

No missing codes over temperature

MAX124_A

MAX124_B

CONDITIONS

Differential Nonlinearity

Aperture Delay

MHz

1.8

SHDN = FLOAT

<50

Aperture Jitter

MHz

0.1

2.0

µs

1.5

ACQ

Track/Hold Acquisition Time

0.225

Internal Clock Frequency

SHDN = V

2.0

External Clock Frequency

Data transfer only

LSB

Gain Error (Note 3)

±2

MAX124_B

DC ACCURACY

(Note 1)

DYNAMIC SPECIFICATIONS

(10kHz sine-wave input, 0V to 2.500Vp-p, 133ksps, 2.0MHz external clock, bipolar input mode)

CONVERSION RATE

MAX1248/MAX1249

+2.7V to +5.25V, Low-Power, 4-Channel,

Serial 10-Bit ADCs in QSOP-16

_______________________________________________________________________________________

Multiplexer Leakage Current

DIN, SCLK, CS Input Capacitance

µA

±0.01

±1

DIN, SCLK, CS Input Leakage

0.2

HYST

DIN, SCLK, CS Input Hysteresis

0.8

DIN, SCLK, CS Input Low Voltage

2.0

µA

0.01

Shutdown VREF Input Current

VREF Input Resistance

µA

100

150

VREF Input Current

1.0

50mV

VREF Input Voltage Range
(Note 9)

Input Capacitance

0 to VREF

±VREF / 2

Input Voltage Range, Single-
Ended and Differential (Note 6)

µA

±0.01

±1

UNITS

MIN

TYP

MAX

SYMBOL

PARAMETER

(Note 10)

= 0V or V

Unipolar, COM = 0V

3.6V

VREF = 2.500V

Bipolar, COM = VREF / 2

On/off leakage current, V

CH_

= 0V or V

CONDITIONS

µA

±4.0

SHDN Input Current

0.4

SHDN Input Low Voltage

- 0.4

SHDN Input High Voltage

SHDN = 0V or V

ELECTRICAL CHARACTERISTICS (continued)

= +2.7V to +5.25V; COM = 0V; f

SCLK

= 2.0MHz; external clock (50% duty cycle); 15 clocks/conversion cycle (133ksps);

MAX1248--4.7µF capacitor at VREF pin; MAX1249--external reference, VREF = 2.500V applied to VREF pin; T

= T

MIN

to T

MAX

unless otherwise noted.)

3.0

DIN, SCLK, CS Input High Voltage

> 3.6V

2.470

2.500

2.530

VREF Output Voltage

= +25°C (Note 7)

VREF Short-Circuit Current

ppm/°C

±30

VREF Temperature Coefficient

MAX1248

µF

Capacitive Bypass at VREF

Internal compensation mode

4.7

External compensation mode

0.35

Load Regulation (Note 8)

0mA to 0.2mA output load

µF

0.01

Capacitive Bypass at REFADJ

±1.5

REFADJ Adjustment Range

DD -

0.5

REFADJ Buffer-Disable Threshold

Capacitive Bypass at VREF

Internal compensation mode

µF

External compensation mode

4.7

Reference-Buffer Gain

MAX1248

2.06

V/V

MAX1249

2.00

REFADJ Input Current

MAX1248

±50

µA

MAX1249

±10

1.1

- 1.1

SHDN Input Mid Voltage

ANALOG/COM INPUTS

EXTERNAL REFERENCE AT VREF

(Buffer disabled)

DIGITAL INPUTS

(DIN, SCLK, CS, SHDN)

EXTERNAL REFERENCE AT REFADJ

INTERNAL REFERENCE

(MAX1248 only, reference buffer enabled)

= 5.25V

MAX1248/MAX1249

+2.7V to +5.25V, Low-Power, 4-Channel,
Serial 10-Bit ADCs in QSOP-16

_______________________________________________________________________________________

1.2

2.0

3.5

Operating mode,
full-scale input (Note 11)

Fast power-down (MAX1248)

±100

SHDN Maximum Allowed
Leakage, Mid Input

/ 2

FLT

SHDN Voltage, Floating

SHDN = FLOAT

UNITS

MIN

TYP

MAX

SYMBOL

PARAMETER

µA

1.2

CONDITIONS

Positive Supply Current

1.6

3.0

µA

±0.01

±10

Three-State Leakage Current

- 0.5

Output Voltage High

0.8

Output Voltage Low

0.4

2.70

5.25

Positive Supply Voltage

OUT

Three-State Output Capacitance

Full power-down

CS = V

(Note 10)

CS = V

SOURCE

= 0.5mA

SINK

= 16mA

SINK

= 5mA

ELECTRICAL CHARACTERISTICS (continued)

= +2.7V to +5.25V; COM = 0V; f

SCLK

= 2.0MHz, external clock (50% duty cycle); 15 clocks/conversion cycle (133ksps);

MAX1248--4.7µF capacitor at VREF pin; MAX1249--external reference; VREF = 2.500V applied to VREF pin, T

= T

MIN

to T

MAX

unless otherwise noted.)

±0.3

PSR

Supply Rejection (Note 12)

= 2.7V to 5.25V, full-scale input,

external reference = 2.500V

DIGITAL OUTPUTS

(DOUT, SSTRB)

POWER REQUIREMENTS

= 5.25V

= 3.6V

= 5.25V

= 3.6V

MAX1248/MAX1249

+2.7V to +5.25V, Low-Power, 4-Channel,

Serial 10-Bit ADCs in QSOP-16

_______________________________________________________________________________________

TIMING CHARACTERISTICS

= +2.7V to +5.25V, T

= T

MIN

to T

MAX

, unless otherwise noted.)

Note 1:

Tested at V

= 2.7V; COM = 0V; unipolar single-ended input mode.

Note 2:

Relative accuracy is the deviation of the analog value at any code from its theoretical value after the full-scale range has
been calibrated.

Note 3:

MAX1248--internal reference, offset nulled; MAX1249 -- external reference (VREF = +2.500V), offset nulled.

Note 4:

Ground "on" channel; sine wave applied to all "off" channels.

Note 5:

Conversion time defined as the number of clock cycles multiplied by the clock period; clock has 50% duty cycle.

Note 6:

The common-mode range for the analog inputs is from AGND to V

Note 7

Sample tested to 0.1% AQL.

Note 8:

External load should not change during conversion for specified accuracy.

Note 9:

ADC performance is limited by the converter's noise floor, typically 300µVp-p.

Note 10

Guaranteed by design. Not subject to production testing.

Note 11:

The MAX1249 typically draws 400

A less than the values shown.

Note 12:

Measured as

(2.7V) - V

(5.25V)

DIN to SCLK Setup

240

STR

CS Rise to SSTRB Output Disable

240

SDV

CS Fall to SSTRB Output Enable

240

SSTRB

SCLK Fall to SSTRB

200

SCLK Pulse Width Low

200

SCLK Pulse Width High

CS to SCLK Rise Hold

100

CSS

CS to SCLK Rise Setup

240

CS Rise to Output Disable

240

CS Fall to Output Enable

SCLK Fall to Output Data Valid

DIN to SCLK Hold

µs

1.5

ACQ

Acquisition Time

SCK

SSTRB Rise to SCLK Rise

100

UNITS

MIN

TYP

MAX

SYMBOL

PARAMETER

Internal clock mode only (Note 10)

External clock mode only, Figure 2

External clock mode only, Figure 1

Figure 1

Figure 2

Figure 1

CONDITIONS

240

Figure 1

CSH

MAX124_ _C/E

MAX124_ _M

200

Part Number MAX1249