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_______________General Description

The MAX196/MAX198 multirange, 12-bit data-acquisi-

tion systems (DAS) require only a single +5V supply for

operation, yet convert analog signals at their inputs up

to ±10V (MAX196) and ±4V (MAX198). These systems

provide six analog input channels that are indepen-

dently software programmable for a variety of ranges:

±10V, ±5V, 0V to +10V, and 0V to +5V for the MAX196;

±V

REF

, ±V

REF

/2, 0V to +V

REF

, and 0V to +V

REF

/2 for

the MAX198. This range switching increases the effec-

tive dynamic range to 14 bits and provides the flexibility

to interface ±12V, ±15V, and 4mA to 20mA powered

sensors to a single +5V system. In addition, these con-

verters are fault protected to ±16.5V; a fault condition

on any channel will not affect the conversion result of

the selected channel. Other features include a 5MHz

bandwidth track/hold, 100ksps throughput rate, soft-

ware-selectable internal/external clock, internal/external

acquisition control, 12-bit parallel interface, and internal

4.096V or external reference.

Two programmable power-down modes (STBYPD,

FULLPD) provide low-current shutdown between con-

versions. In STBYPD mode, the reference buffer

remains active, eliminating start-up delays.

The MAX196/MAX198 employ a standard microproces-

sor (µP) interface. A three-state data I/O port is config-

ured to operate with 16-bit data buses, and data-

access and bus-release timing specifications are com-

patible with most popular µPs. All logic inputs and out-

puts are TTL/CMOS compatible.

These devices are available in 28-pin DIP, wide SO,

SSOP (55% smaller in area than wide SO), and ceramic

SB packages. For 8+4 bus interface, see the MAX197

and the MAX199 data sheets. An evaluation kit will be

available after December 1995 (MAX196EVKIT-DIP).

________________________Applications

Industrial-Control Systems

Robotics

Data-Acquisition Systems

Automatic Testing Systems

Medical Instruments

Telecommunications

____________________________Features

♦ 12-Bit Resolution, 1/2LSB Linearity

♦ Single +5V Supply Operation

♦ Software-Selectable Input Ranges:

±10V, ±5V, 0V to +10V, 0V to +5V (MAX196)

±V

REF

, ±V

REF

/2, 0V to +V

REF

, 0V to +V

REF

(MAX198)

♦ Internal 4.096V or External Reference

♦ Fault-Protected Input Multiplexer

♦ 6 Analog Input Channels

♦ 6µs Conversion Time, 100ksps Sampling Rate

♦ Internal or External Acquisition Control

♦ Two Power-Down Modes

♦ Internal or External Clock

MAX196/MAX198

Multirange, Single +5V, 12-Bit DAS

with 12-Bit Bus Interface

________________________________________________________________

Maxim Integrated Products

DGND

INT

REF

AGND

REFADJ

CH5

CH4

CH3

CH2

CH1

CH0

D10

D11

CLK

DIP/SO/SSOP/Ceramic SB

TOP VIEW

MAX196

MAX198

__________________Pin Configuration

Call toll free 1-800-722-8266 for free samples or literature.

19-0435; Rev 0; 9/95

PART

MAX196ACNI

MAX196BCNI

MAX196ACWI 0°C to +70°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

28 Narrow Plastic DIP

28 Wide SO

EVALUATION KIT

AVAILABLE

______________Ordering Information

MAX196BCWI 0°C to +70°C 28 Wide SO

Functional Diagram appears at end of data sheet.

Ordering Information continued at end of data sheet.

MAX196ACAI 0°C to +70°C 28 SSOP

MAX196BCAI 0°C to +70°C 28 SSOP

Summary of content (16 pages)

PAGE 1
9-0435; Rev 0; 9/95 KIT ATION EVALU E L B A IL AVA Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface ________________________Applications Industrial-Control Systems Robotics Data-Acquisition Systems Automatic Testing Systems Medical Instruments Telecommunications Functional Diagram appears at end of data sheet.
PAGE 2
MAX196/MAX198 Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface ABSOLUTE MAXIMUM RATINGS VDD to AGND............................................................-0.3V to +7V AGND to DGND.....................................................-0.3V to +0.3V REF to AGND..............................................-0.3V to (VDD + 0.3V) REFADJ to AGND.......................................-0.3V to (VDD + 0.3V) Digital Inputs to DGND...............................-0.3V to (VDD + 0.
PAGE 3
Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface (VDD = 5V ±5%; unipolar/bipolar range; external reference mode, VREF = 4.096V; 4.7µF at REF pin; external clock, fCLK = 2.0MHz with 50% duty cycle; TA = TMIN to TMAX; unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 3 µs ANALOG INPUT Track/Hold Acquisition Time fCLK = 2.0MHz -3dB rolloff Small-Signal Bandwidth ±10V or ±VREF range 5 ±5V or ±VREF/2 range 2.
PAGE 4
MAX196/MAX198 Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface ELECTRICAL CHARACTERISTICS (continued) (VDD = 5V ±5%; unipolar/bipolar range; external reference mode, VREF = 4.096V; 4.7µF at REF pin; external clock, fCLK = 2.0MHz with 50% duty cycle; TA = TMIN to TMAX; unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 4.18 V REFERENCE INPUT (buffer disabled, reference input applied to REF pin) Input Voltage Range 2.4 VREF = 4.
PAGE 5
Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface (VDD = 5V ±5%; unipolar/bipolar range; external reference mode, VREF = 4.096V; 4.7µF at REF pin; external clock, fCLK = 2.0MHz with 50% duty cycle; TA = TMIN to TMAX; unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0.4 V 15 pF DIGITAL OUTPUTS (D11–D0, INT) Output Low Voltage VOL VDD = 4.75V, ISINK = 1.6mA Output High Voltage VOH VDD = 4.
PAGE 6
__________________________________________Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) fTONE = 10kHz fSAMPLE = 100kHz -20 fSAMPLE = 100kHz 0.050 0 -40 -60 -80 -0.050 -100 -0.100 -120 0 1000 2000 3000 4000 25 MAX196/8-4 0.4 VDD = 5V ±0.25V 0.2 VREF (V) PSRR (LSB) REF CHANNEL-TO-CHANNEL OFFSET-ERROR MATCHING vs. TEMPERATURE 100Hz -0.2 0.18 0.16 0.14 0.12 0.10 -70 -50 -30 -10 10 30 50 70 90 110 130 CHANNEL-TO-CHANNEL GAIN-ERROR MATCHING vs. TEMPERATURE 0.
PAGE 7
Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface PIN NAME FUNCTION CLK Clock Input. In external clock mode, drive CLK with a TTL/CMOS-compatible clock. In internal clock mode, place a capacitor (CCLK) from this pin to ground to set the internal clock frequency; fCLK = 1.56MHz typical with CCLK = 100pF. Chip Select, active low 1 2 CS 3–14 D11–D0 15 AGND 16–21 CH0–CH5 Analog Input Channels 22 REFADJ Bandgap Voltage-Reference Output/External Adjust Pin. Bypass with a 0.
PAGE 8
MAX196/MAX198 Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface Acquisition time is calculated as follows: For 0V to VREF: tAZ = 9 x (RS + RIN) x 16pF For 0V to VREF/2: tAZ = 9 x (RS + RIN) x 32pF where RIN = 7kΩ and tAZ is never less than 2µs (0V to VREF range) or 3µs (0V to VREF/2 range).
PAGE 9
Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface MAX196/MAX198 Table 2. Control-Byte Format D7 (MSB) D6 D5 D4 D3 D2 D1 D0 (LSB) PD1 PD0 ACQMOD RNG BIP A2 A1 A0 BIT NAME 7, 6 PD1, PD0 These two bits select the clock and power-down modes (Table 4). 5 ACQMOD 0 = internally controlled acquisition (6 clock cycles), 1 = externally controlled acquisition 4 RNG 3 BIP 2, 1, 0 A2, A1, A0 DESCRIPTION Selects the full-scale voltage magnitude at the input (Table 3).
PAGE 10
MAX196/MAX198 Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface Input Format The control byte is latched into the device, on pins D7–D0, during a write cycle. Table 2 shows the controlbyte format. duration is internally timed. Conversion starts when this six-clock-cycle acquisition interval (3µs with f CLK = 2MHz) ends (see Figure 5).
PAGE 11
Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface MAX196/MAX198 tCSRS tCS tCSRH CS tCSWS tWR tACQI tCSHW tCONV WR tDH tDS D7–D0 CONTROL BYTE ACQMOD = "1" CONTROL BYTE ACQMOD = "0" tINT1 INT RD tD0 tTR DATA VALID DOUT Figure 6. Conversion Timing Using External Acquisition Mode Internal Clock Mode Select internal clock mode to free the µP from the burden of running the SAR conversion clock. To select this mode, write the control byte with D7 = 0 and D6 = 1.
PAGE 12
MAX196/MAX198 Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface ACQUISITION STARTS ACQUISITION ENDS CONVERSION STARTS CLK tCWS WR ACQMOD = "0" tCWH WR GOES HIGH WHEN CLK IS HIGH ACQUISITION ENDS ACQUISITION STARTS CONVERSION STARTS CLK WR ACQMOD = "0" WR GOES HIGH WHEN CLK IS LOW Figure 8a.
PAGE 13
Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface REF Power-On Reset At power-up, the internal power-on reset circuitry sets INT high and puts the device in normal operation/external clock mode. This state is selected to keep the internal clock from loading the external clock driver when the part is used in external clock mode. 4.096V 26 4.7µF CREF MAX196 MAX198 AV = 1.638 REFADJ 25 Internal or External Reference The MAX196/MAX198 can operate with either an internal or external reference.
PAGE 14
MAX196/MAX198 Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface results may be read. Input overvoltage protection is active in all power-down modes. The device returns to normal operation on the first WR falling edge during write operation. Choosing Power-Down Modes The bandgap reference and reference buffer remain active in STBYPD mode, maintaining the voltage on the 4.7µF capacitor at the REF pin. This is a “DC” state that does not degrade after power-down of any duration.
PAGE 15
Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface MAX196/MAX198 Layout, Grounding, and Bypassing Careful printed circuit board layout is essential for best system performance. For best performance, use a ground plane. To reduce crosstalk and noise injection, keep analog and digital signals separate. Digital ground lines can run between digital signal lines to minimize interference. Connect analog grounds and DGND in a star configuration to AGND.
PAGE 16
MAX196/MAX198 Multirange, Single +5V, 12-Bit DAS with 12-Bit Bus Interface _Ordering Information (continued) PART TEMP.