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General Description

The MAX157/MAX159 low-power, 10-bit analog-to-digi-

tal converters (ADCs) are available in 8-pin µMAX and

DIP packages. Both devices operate with a single

+2.7V to +5.25V supply and feature a 7.4µs succes-

sive-approximation ADC, automatic power-down, fast

wake-up (2.5µs), an on-chip clock, and a high-speed,

3-wire serial interface.

Power consumption is only 3.2mW (V

= +3.6V) at the

maximum sampling rate of 108ksps. At slower through-

put rates, the 0.2µA automatic shutdown further

reduces power consumption.

The MAX157 provides 2-channel, single-ended opera-

tion and accepts input signals from 0 to V

REF

. The

MAX159 accepts pseudo-differential inputs ranging

from 0 to V

REF

. An external clock accesses data

through the 3-wire serial interface, which is SPI™,

QSPI™, and MICROWIRE™ compatible.

Excellent dynamic performance and low power, com-

bined with ease of use and a small package size, make

these converters ideal for battery-powered and data

acquisition applications, or for other circuits with

demanding power-consumption and space require-

ments. For pin-compatible 12-bit upgrades, see the

MAX144/MAX145 data sheet.

Applications

Battery-Powered Systems Instrumentation

Portable Data Logging Test Equipment

Isolated Data Acquisition Medical Instruments

Process-Control Monitoring System Supervision

Features

♦ Single-Supply Operation (+2.7V to +5.25V)

♦ Two Single-Ended Channels (MAX157)

Single Pseudo-Differential Channel (MAX159)

♦ Low Power

0.9mA (at 108ksps, +3V)

100µA (at 10ksps, +3V)

10µA (at 1ksps, +3V)

<0.2µA (power-down mode)

♦ Internal Track/Hold

♦ 108ksps Sampling Rate

♦ SPI/QSPI/MICROWIRE-Compatible 3-Wire

Serial Interface

♦ Space-Saving 8-Pin µMAX Package

♦ Pin-Compatible 12-Bit Upgrades Available

MAX157/MAX159

+2.7V, Low-Power, 2-Channel,

108ksps, Serial 10-Bit ADCs in 8-Pin µMAX

________________________________________________________________

Maxim Integrated Products

CS/SHDN

REFGND

SCLK

DOUT

( ) ARE FOR MAX159 ONLY.

CH0 (CH+)

CH1 (CH-)

µMAX/DIP

TOP VIEW

MAX157

MAX159

19-1388; Rev 0; 11/98

Pin Configuration

Ordering Information

SPI and QSPI are trademarks of Motorola, Inc.

MICROWIRE is a trademark of National Semiconductor Corp.

Contact factory for availability.

±18 CERDIP*-55°C to +125°CMAX159BMJA

±0.58 CERDIP*-55°C to +125°CMAX159AMJA

±18 Plastic DIP-40°C to +85°CMAX159BEPA

±0.58 Plastic DIP-40°C to +85°CMAX159AEPA

±18 µMAX-40°C to +85°CMAX159BEUA

±1

±0.5

±1

±0.5

±1

±0.5

±1

±0.5

±1

±0.5

±1

±0.5

±1

±0.5

INL

(LSB)

8 CERDIP*

8 Plastic DIP-40°C to +85°C

-55°C to +125°C

-55°C to +125°CMAX157BMJA

MAX157AMJA

MAX157BEPA

8 Plastic DIP

8 µMAX-40°C to +85°C

-40°C to +85°CMAX157AEPA

MAX157BEUA

8 µMAX

8 Plastic DIP0°C to +70°C

-40°C to +85°CMAX159AEUA

MAX159BCPA

8 Plastic DIP

8 µMAX

8 µMAX0°C to +70°C

0°C to +70°C

0°C to +70°CMAX159ACPA

MAX159BCUA

MAX159ACUA

8 µMAX

8 Plastic DIP0°C to +70°C

-40°C to +85°CMAX157AEUA

MAX157BCPA

8 Plastic DIP

8 µMAX

PIN-

PACKAGE

TEMP.

RANGE

0°C to +70°C

0°C to +70°CMAX157ACPA

MAX157BCUA

MAX157ACUA

PART

Summary of content (16 pages)

PAGE 1
9-1388; Rev 0; 11/98 +2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX The MAX157/MAX159 low-power, 10-bit analog-to-digital converters (ADCs) are available in 8-pin µMAX and DIP packages. Both devices operate with a single +2.7V to +5.25V supply and feature a 7.4µs successive-approximation ADC, automatic power-down, fast wake-up (2.5µs), an on-chip clock, and a high-speed, 3-wire serial interface. Power consumption is only 3.2mW (VDD = +3.6V) at the maximum sampling rate of 108ksps.
PAGE 2
MAX157/MAX159 +2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX ABSOLUTE MAXIMUM RATINGS VDD to GND. .............................................................-0.3V to +6V CH0, CH1 (CH+, CH-) to GND...................-0.3V to (VDD + 0.3V) REF to GND ................................................-0.3V to (VDD + 0.3V) Digital Inputs to GND ...............................................-0.3V to +6V DOUT to GND.............................................-0.3V to (VDD + 0.
PAGE 3
+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX (V DD = +2.7V to +5.25V, V REF = 2.5V, 0.1µF capacitor at REF, f SCLK = 2.17MHz, 16 clocks/conversion cycle (108ksps), CH- = GND for MAX159, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS CONVERSION RATE Conversion Time (Note 5) tCONV T/H Acquisition Time tACQ External clock, fSCLK = 2.17MHz, 16 clock cycles per conversion Internal clock 7.
PAGE 4
MAX157/MAX159 +2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX ELECTRICAL CHARACTERISTICS (continued) (V DD = +2.7V to +5.25V, V REF = 2.5V, 0.1µF capacitor at REF, f SCLK = 2.17MHz, 16 clocks/conversion cycle (108ksps), CH- = GND for MAX159, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS POWER REQUIREMENTS Positive Supply Voltage VDD +5.25 V Positive Supply Current IDD Operating mode +2.7 0.
PAGE 5
+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX SUPPLY CURRENT vs. TEMPERATURE 900 1250 10,000 MAX157/159 toc02 VREF = VDD RL = ∞ CL = 50pF CODE = 1010101000 VREF = VDD CODE = 1010101000 CL = 50pF 1000 SUPPLY CURRENT (µA) 1100 1500 SUPPLY CURRENT (µA) VREF = VDD RL = ∞ CL = 50pF CODE = 1010101000 1300 1000 750 100 10 700 1 500 500 4.0 4.5 5.0 0.1 -60 -40 -20 0 5.5 20 40 60 80 100 120 140 0.
PAGE 6
Typical Operating Characteristics (continued) (VDD = +3.0V, VREF = 2.5V, 0.1µF capacitor at REF, fSCLK = 2.17MHz, 16 clocks/conversion cycle (108ksps); CH- = GND for MAX159; TA = +25°C, unless otherwise noted.) GAIN ERROR vs. SUPPLY VOLTAGE INTEGRAL NONLINEARITY vs. OUTPUT CODE GAIN ERROR vs. TEMPERATURE 0.1 0 -0.1 MAX157/8 toc10 0.02 0.01 INL (LSB) GAIN ERROR (LSB) 0.1 0.03 MAX157/159 toc09 0.2 MAX157/159 toc08 0.2 GAIN ERROR (LSB) 0 0 -0.01 -0.1 -0.02 -0.2 -0.03 -0.2 2.5 3.0 3.5 4.
PAGE 7
+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX PIN NAME FUNCTION 1 VDD 2 CH0 (CH+) Positive Supply Voltage, +2.7V to +5.25V Analog Input, MAX157: Single-Ended (CH0); MAX159: Differential (CH+). 3 CH1 (CH-) Analog Input, MAX157: Single-Ended (CH1); MAX159: Differential (CH-). 4 GND Analog and Digital Ground 5 REF External Reference Voltage Input. Sets analog voltage range. Bypass with a 100nF capacitor close to the part.
PAGE 8
MAX157/MAX159 +2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX The capacitive digital-to-analog converter (DAC) adjusts during the remainder of the conversion cycle to restore node ZERO to 0V within the limits of 10-bit resolution. This action is equivalent to transferring a 16pF · [(VIN+) - (VIN-)] charge from CHOLD to the binary-weighted capacitive DAC, which in turn forms a digital representation of the analog input signal.
PAGE 9
+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX External Clock (fSCLK = 100kHz to 2.17MHz) External clock mode (Figure 6) is selected by transitioning CS/SHDN from high to low while SCLK is low. The external clock signal not only shifts data out, but also drives the analog-to-digital conversion. The input is sampled and conversion begins on the falling edge of the second clock pulse.
PAGE 10
MAX157/MAX159 +2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX Output Data Format Automatic Power-Down Mode Table 1 illustrates the 16-bit, serial data-stream output format for both the MAX157 and MAX159. The first three bits are always logic high (including the EOC bit for internal clock mode), followed by the channel identification (CHID = 0 for CH0, CHID = 1 for CH1, CHID = 1 for MAX159), the 10 bits of data in MSB first format, and two sub-LSB bits (S1 and S0).
PAGE 11
+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX SCLK CYCLE 1 2 3 DOUT (Internal Clock) EOC 1 1 DOUT (External Clock) 1 1 1 4 5 6 7 8 9 10 11 12 13 14 15 16 CHID D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 S1 S0 CHID D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 S1 S0 etc. Therefore, SNR is computed by taking the ratio of the RMS signal to the RMS noise (which includes all spectral components minus the fundamental), the first five harmonics, and the DC offset.
PAGE 12
MAX157/MAX159 +2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX CS/SHDN I/O CS/SHDN SCK SCLK SK SCLK MISO DOUT SI DOUT I/O VDD SPI MICROWIRE MAX157 MAX159 MAX157 MAX159 SS Figure 8a. SPI Connections Figure 8b.
PAGE 13
+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 HIGH-Z CHID DOUT D9 SAMPLING INSTANT *WHEN CS/SHDN IS HIGH, DOUT = HIGH - Z D8 D7 D6 D5 D4 D3 D2 D1 MSB D0 S1 S0 LSB Figure 9b. QSPI Interface Timing Sequence (CPOL = CPHA = 0) VDD star-point (Figure 11) connecting the two ground systems (analog and digital).
PAGE 14
MAX157/MAX159 +2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX Table 2. Detailed SSPCON Register Content CONTROL BIT MAX157/MAX159 SETTINGS SYNCHRONOUS SERIAL PORT CONTROL REGISTER (SSPCON) WCOL Bit 7 X Write Collision Detection Bit SSPOV Bit 6 X Receive Overflow Detect Bit SSPEN Bit 5 1 Synchronous Serial Port Enable Bit 0: Disables serial port and configures these pins as I/O port pins. 1: Enables serial port and configures SCK, SDO and SCI pins as serial port pins.
PAGE 15
+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX TRANSISTOR COUNT: 2,058 SUBSTRATE CONNECTED TO GND 8LUMAXD.
PAGE 16
+2.7V, Low-Power, 2-Channel, 108ksps, Serial 10-Bit ADCs in 8-Pin µMAX PDIPN.EPS MAX157/MAX159 Package Information (continued) 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.