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General Description

The MAX1144/MAX1145 are 150ksps, 14-bit ADCs.

These serially interfaced ADCs connect directly to

SPI™, QSPI™, and MICROWIRE™ devices without

external logic. They combine an input scaling network,

internal track/hold, clock, and three general-purpose

digital output pins (for external multiplexer or PGA con-

trol) in a 20-pin SSOP package. The excellent dynamic

performance (THD ≥ 90dB), high speed (150ksps in

bipolar mode), and low power (8.0mA) of these ADCs

make them ideal for applications such as industrial

process control, instrumentation, and medical applica-

tions.

The MAX1144 accepts input signals of 0 to +6V (unipo-

lar) or ±6V (bipolar), while the MAX1145 accepts input

signals of 0 to +2.048V (unipolar) or ±2.048V (bipolar).

Operating from a single 3.135V to 3.465V analog digital

supply, powerdown modes reduce current consump-

tion to 0.15mA at 10ksps and further reduce supply

current to less than 20µA slower data rates.

A serial strobe output (SSTRB) allows direct connection

to the TMS320 family digital-signal processors. The

MAX1144/MAX1145 user can select either the internal

clock or an external serial-interface clock for the ADC to

perform analog-to-digital conversions.

The MAX1144/MAX1145 feature internal calibration cir-

cuitry to correct linearity and offset errors. On-demand

calibration allows the user to optimize performance.

Three user-programmable logic outputs are provided

for the control of an 8-channel mux or PGA.

The MAX1144/MAX1145 are available in a 20-pin SSOP

package and are fully specified over the -40°C to

+85°C temperature range.

Applications

Industrial Process Control

Industrial I/O Modules

Data-Acquisition Systems

Medical Instruments

Portable and Battery-Powered Equipment

Features

♦ 150ksps (Bipolar) and 125ksps (Unipolar)

Sampling ADC

♦ 14 Bits, No Missing Codes

♦ 1LSB INL Guaranteed

♦ -100dB THD

♦ 3.3V Single-Supply Operation

♦ Low-Power Operation

5mA typ (Unipolar Mode)

♦ 1.2µA Shutdown Mode

♦ Software-Configurable Unipolar and Bipolar Input

Ranges

0 to +6V and ±6V (MAX1144)

0 to +2.048V and ±2.048V (MAX1145)

♦ Internal or External Clock

♦ SPI/QSPI/MICROWIRE TMS320-Compatible Serial

Interface

♦ Three User-Programmable Logic Outputs

♦ Small 20-Pin SSOP Package

MAX1144/MAX1145

14-Bit ADCs, 150ksps, 3.3V Single Supply

________________________________________________________________ Maxim Integrated Products 1

AIN

AGND

CREF

CSAV

AGND

REF

TOP VIEW

DIN

DGND

SCLKP1

SHDN

DGND

RST

DOUTSSTRB

MAX1144

MAX1145

SSOP

Pin Configuration

Ordering Information

19-2465; Rev 0; 4/02

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.

Ordering Information continued at end of data sheet.

Functional Diagram and Typical Application Circuit appear

at end of data sheet.

PART

TEMP

RANGE

PIN-

PACKAGE

INL

(LSB)

MAX1144ACAP 0°C to +70°C 20 SSOP ±1

MAX1144BCAP 0°C to +70°C 20 SSOP ±2

MAX1144AEAP -40°C to +85°C 20 SSOP ±1

MAX1144BEAP -40°C to +85°C 20 SSOP ±2

SPI and QSPI are trademarks of Motorola, Inc.

MICROWIRE is a trademark of National Semiconductor, Corp.

Summary of content (18 pages)

PAGE 1
9-2465; Rev 0; 4/02 14-Bit ADCs, 150ksps, 3.3V Single Supply Features ♦ 150ksps (Bipolar) and 125ksps (Unipolar) Sampling ADC ♦ 14 Bits, No Missing Codes ♦ 1LSB INL Guaranteed ♦ -100dB THD ♦ 3.3V Single-Supply Operation ♦ Low-Power Operation 5mA typ (Unipolar Mode) ♦ 1.2µA Shutdown Mode ♦ Software-Configurable Unipolar and Bipolar Input Ranges 0 to +6V and ±6V (MAX1144) 0 to +2.048V and ±2.
PAGE 2
MAX1144/MAX1145 14-Bit ADCs, 150ksps, 3.3V Single Supply ABSOLUTE MAXIMUM RATINGS AVDD to AGND, DVDD to DGND ..............................-0.3V to +6V AGND to DGND.....................................................-0.3V to +0.3V AIN to AGND ....................................................................±16.5V CREF, REF to AGND ................................-0.3V to (AVDD + 0.3V) Digital Inputs to DGND.............................................-0.3V to +6V Digital Outputs to DGND ...............
PAGE 3
14-Bit ADCs, 150ksps, 3.3V Single Supply (AVDD = DVDD = 3.3V ±5%, fSCLK = 3.6MHz, external clock (50% duty cycle), 24 clocks/conversion (150ksps), bipolar input, VREF = 2.048V, CREF = 4.7µF, CCREF = 1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MAX1144 Input Impedance MAX1145 MIN TYP 10.5 Unipolar 7.5 Bipolar 5.9 8.4 Unipolar 100 1000 Bipolar 3.4 5.
PAGE 4
MAX1144/MAX1145 14-Bit ADCs, 150ksps, 3.3V Single Supply ELECTRICAL CHARACTERISTICS (continued) (AVDD = DVDD = 3.3V ±5%, fSCLK = 3.6MHz, external clock (50% duty cycle), 24 clocks/conversion (150ksps), bipolar input, VREF = 2.048V, CREF = 4.7µF, CCREF = 1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Input Hysteresis Input Capacitance SYMBOL CONDITIONS MIN TYP MAX UNITS VHYST 0.
PAGE 5
14-Bit ADCs, 150ksps, 3.3V Single Supply (AVDD = DVDD = 3.3V ±5%, TA = TMIN to TMAX, unless otherwise noted.) Note 1: Tested at AVDD = DVDD = 3.3V, bipolar input mode. Note 2: Relative accuracy is the deviation of the analog value at any code from its theoretical value after the gain error and offset error have been nullified. Note 3: Offset nullified. Note 4: Conversion time is defined as the number of clock cycles multiplied by the clock period; clock has 50% duty cycle. Includes the acquisition time.
PAGE 6
Typical Operating Characteristics (continued) (MAX1144/MAX1145, AVDD = DVDD = 3.3V, fSCLK = 3.6MHz, external clock (50% duty cycle), 24 clocks/conversion (150ksps), bipolar input, REF = 2.048V, 4.7µF on REF, 1µF on CREF, TA = +25°C, unless otherwise noted.) C A -1.5 -2.0 0.04 C 0.03 A 0.02 A: AVDD, DVDD = 3.135V B: AVDD, DVDD = 3.3V C: AVDD, DVDD = 3.465V 0.01 B -2.5 0 -40 -20 0 20 40 60 80 MAX1144/45 toc06 B 10 1 0.1 0.
PAGE 7
14-Bit ADCs, 150ksps, 3.3V Single Supply PIN NAME FUNCTION 1 REF 2 AVDD Analog Supply. Connect to pin 4. 3 AGND Analog Ground. This is the primary analog ground (star ground). 4 AVDD Analog Supply, 3.3V ±5%. Bypass AVDD to AGND (pin 3) with a 0.1µF capacitor. 5 DGND Digital Ground 6 SHDN Shutdown Control Input. Drive SHDN low to put the ADC in shutdown mode.
PAGE 8
MAX1144/MAX1145 14-Bit ADCs, 150ksps, 3.3V Single Supply Detailed Description The MAX1144/MAX1145 ADCs use a successiveapproximation technique and input track/hold (T/H) circuitry to convert an analog signal to a 14-bit digital output. The MAX1144/MAX1145 easily interface to microprocessors (µPs). The data bits can be read either during the conversion in external clock mode or after the conversion in internal clock mode.
PAGE 9
14-Bit ADCs, 150ksps, 3.3V Single Supply MAX1144/MAX1145 CS tACQ SCLK DIN 1 4 UNI/ START BIP INT/ EXT M1 8 M0 P2 P1 15 12 21 24 P0 SSTRB B13 MSB DOUT A/D STATE IDLE B12 B11 ACQUISITION B10 B9 B8 B7 B2 B1 B0 LSB X CONVERSION X FILLED WITH ZEROS IDLE Figure 2. Short Acquisition Mode (24 Clock Cycles) External Clock Table 2.
PAGE 10
MAX1144/MAX1145 14-Bit ADCs, 150ksps, 3.3V Single Supply CS tACQ 1 SCLK DIN UNI/ START BIP 4 INT/ EXT M1 14 8 M0 P2 P1 15 29 32 P0 SSTRB B13 MSB DOUT A/D STATE IDLE ACQUISITION B12 B11 B2 B1 B0 LSB X X CONVERSION FILLED WITH ZEROS IDLE Figure 3. Long Acquisition Mode (32 Clock Cycles) External Clock CS tSTR tSDV SSTRB tSSTRB tSSTRB SCLK P1 CLOCKED IN Figure 4.
PAGE 11
14-Bit ADCs, 150ksps, 3.3V Single Supply MAX1144/MAX1145 CS tACQ SCLK DIN 1 4 UNI/ START BIP INT/ EXT M1 9 8 M0 P2 P1 21 24 P0 SSTRB tCONV B13 MSB DOUT B12 B2 B1 B0 LSB X X FILLED WITH ZEROS Figure 5. Internal Clock Mode Timing, Short Acquisition, Bipolar Mode CS tCONV tCSS tSCK tCSH SSTRB t SSTRB SCLK P0 CLOCKED IN NOTE: FOR BEST NOISE PERFORMANCE, KEEP SCLK LOW DURING CONVERSION. Figure 6.
PAGE 12
MAX1144/MAX1145 14-Bit ADCs, 150ksps, 3.3V Single Supply Table 3. Unipolar Full Scale and Zero Scale PART ZERO SCALE FULL SCALE MAX1144 0 6 (VREF/2.048) MAX1145 0 VREF When internal clock mode is selected, SSTRB does not go into a high-impedance state when CS goes high. Figure 6 shows the SSTRB timing in internal clock mode. In internal clock mode, data can be shifted into the MAX1144/MAX1145 at clock rates up to 4MHz, provided the minimum acquisition time, t ACQ , is kept above 1.
PAGE 13
14-Bit ADCs, 150ksps, 3.3V Single Supply MAX1144/MAX1145 1kΩ VCC 0.1µF 2 100pF 7 6 AIN IN 1kΩ 3 4 0.1µF 0.0033µF VEE Figure 7. AIN Buffer for AC/DC Use Input Acquisition and Settling Clocking in a control byte starts input acquisition. The main capacitor array starts acquiring the input as soon as a start bit is recognized, using the same input range as the previous conversion. If the opposite input range is selected by the second DIN bit, the part immediately switches to the new sampling mode.
PAGE 14
MAX1144/MAX1145 14-Bit ADCs, 150ksps, 3.3V Single Supply magnitude of the offset produced by a synchronous signal depends on the signal’s shape, recalibration may be appropriate if the shape or relative timing of the clock or other digital signals change, which can occur if more than one clock signal or frequency is used. Distortion Avoid degrading dynamic performance by choosing an amplifier with distortion much less than the MAX1144/MAX1145’s THD (-90dB) at frequencies of interest.
PAGE 15
14-Bit ADCs, 150ksps, 3.3V Single Supply MAX1144/MAX1145 OUTPUT CODE OUTPUT CODE FULL-SCALE TRANSITION 11 . . . 111 011 . . . 111 011 . . . 110 11 . . . 110 11 . . . 101 000 . . . 010 +FS = +2.048V -FS = -2.048V 1LSB = 4.096V 16384 000 . . . 001 FS = 2.048V 1LSB = FS 16384 000 . . . 000 111 . . . 111 111 . . . 110 111 . . . 101 00 . . . 011 00 . . . 010 100 . . . 001 00 . . . 001 100 . . . 000 00 . . .
PAGE 16
MAX1144/MAX1145 14-Bit ADCs, 150ksps, 3.3V Single Supply Signal-to-Noise Plus Distortion Signal-to-noise plus distortion (SINAD) is the ratio of the fundamental input frequency’s RMS amplitude to the RMS equivalent of all other ADC output signals: SINAD (dB) = 20 x log (SignalRMS / NoiseRMS) Total Harmonic Distortion Total harmonic distortion (THD) is the ratio of the RMS sum of the first five harmonics of the input signal to the fundamental itself.
PAGE 17
14-Bit ADCs, 150ksps, 3.3V Single Supply 3.3V 0.1µF AVDD SHDN Ordering Information (continued) PART TEMP RANGE MAX1145ACAP 0°C to +70°C PINPACKAGE INL (LSB) 20 SSOP ±1 MAX1145BCAP 0°C to +70°C 20 SSOP ±2 MAX1145AEAP -40°C to +85°C 20 SSOP ±1 MAX1145BEAP -40°C to +85°C 20 SSOP ±2 3.3V DVDD AIN 0.1µF MAX1144/ MAX1145 2.048V REF CREF 4.
PAGE 18
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) SSOP.EPS MAX1144/MAX1145 14-Bit ADCs, 150ksps, 3.3V Single Supply Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.