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_______________General Description

The MAX199 multi-range, 12-bit data-acquisition system

(DAS) requires only a single +5V supply for operation,

and converts analog signals up to ±4V at its inputs. This

system provides eight analog input channels that are

independently software programmable for a variety of

ranges: ±V

REF

, ±V

REF/2

, 0V to V

REF

, or 0V to V

REF/2

This increases effective dynamic range to 14 bits, and

provides the user flexibility to interface 4mA-to-20mA,

±12V, and ±15V powered sensors to a single +5V sys-

tem. In addition, the converter is fault-protected to

±16.5V; a fault condition on any channel will not affect

the conversion result of the selected channel. Other fea-

tures include a 5MHz bandwidth track/hold, 100ksps

throughput rate, internal/external clock, internal/external

acquisition control, 8+4 parallel interface, and operation

with an internal 4.096V or external reference.

A hardware SHDN pin and two programmable power-

down modes (STBYPD, FULLPD) provide low-current

shutdown between conversions. In STBYPD mode, the

reference buffer remains active, eliminating start-up

delays.

The MAX199 employs a standard microprocessor (µP)

interface. Its three-state data I/O interface is configured

to operate with 8-bit data buses, and data-access and

bus-release timing specifications are compatible with

most popular µPs. All logic inputs and outputs are

TTL/CMOS compatible.

The MAX199 is available in 28-pin DIP, wide SO, SSOP,

and ceramic SB packages.

For a different combination of input ranges (±10V, ±5V,

0V to 10V, 0V to 5V), see the MAX197 data sheet. For 12-

bit bus interfaces, see the MAX196/MAX198 data sheet.

________________________Applications

Industrial-Control Systems

Robotics

Data-Acquisition Systems

Automatic Testing Systems

Medical Instruments

Telecommunications

____________________________Features

♦ 12-Bit Resolution, 1/2LSB Linearity

♦ Single +5V Operation

♦ Software-Selectable Input Ranges:

±V

REF

, ±V

REF/2

, 0V to V

REF

, 0V to V

REF/2

♦ Internal 4.096V or External Reference

♦ Fault-Protected Input Multiplexer (±16.5V)

♦ 8 Analog Input Channels

♦ 6µs Conversion Time, 100ksps Sampling Rate

♦ Internal or External Acquisition Control

♦ Two Power-Down Modes

♦ Internal or External Clock

MAX199

Multi-Range (±4V, ±2V, +4V, +2V),

+5V Supply, 12-Bit DAS with 8+4 Bus Interface

________________________________________________________________

Maxim Integrated Products

DGND

REF

REFADJ

INT

CH7

AGND

CH6

CH5

CH4

CH3

CH2

CH1

CH0

D0/D8

D1/D9

D2/D10

D3/D11

SHDN

HBEN

CLK

DIP/SO/SSOP/Ceramic SB

TOP VIEW

MAX199

__________________Pin Configuration

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

19-0401; Rev 0; 6/95

PART

MAX199ACNI

MAX199BCNI

MAX199ACWI 0°C to +70°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

28 Narrow Plastic DIP

28 Wide SO

______________Ordering Information

MAX199BCWI 0°C to +70°C 28 Wide SO

MAX199ACAI 0°C to +70°C 28 SSOP

MAX199BCAI 0°C to +70°C 28 SSOP

MAX199BC/D 0°C to +70°C Dice*

Functional Diagram appears at end of data sheet.

Ordering Information continued at end of data sheet.

*Dice are specified at T

= +25°C, DC parameters only.

Summary of content (16 pages)

PAGE 1
9-0401; Rev 0; 6/95 Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface ________________________Applications Industrial-Control Systems Robotics Data-Acquisition Systems Automatic Testing Systems Medical Instruments Telecommunications Functional Diagram appears at end of data sheet. ____________________________Features ♦ 12-Bit Resolution, 1/2LSB Linearity ♦ Single +5V Operation ♦ Software-Selectable Input Ranges: ±VREF, ±VREF/2, 0V to VREF, 0V to VREF/2 ♦ Internal 4.
PAGE 2
MAX199 Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 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
Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 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.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 3 µs ANALOG INPUT Track/Hold Acquisition Time fCLK = 2.0MHz ±VREF range Small-Signal Bandwidth -3dB rolloff 5 ±VREF/2 range 2.5 0V to VREF range 2.
PAGE 4
MAX199 Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 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.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.25 V POWER REQUIREMENTS Supply Voltage VDD 4.
PAGE 5
Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 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.
PAGE 6
__________________________________________Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) EFFECTIVE NUMBER OF BITS vs. INPUT FREQUENCY FFT PLOT fTONE = 10kHz fSAMPLE = 100kHz -20 0 -40 -60 -80 -0.050 -100 -0.100 -120 -0.150 0 2000 1000 3000 4000 0 25 50 FREQUENCY (kHz) DIGITAL CODE MAX199-4 CHANNEL-TO-CHANNEL OFFSET-ERROR MATCHING vs. TEMPERATURE 120Hz 0 100Hz -0.2 CHANNEL-TO-CHANNEL GAIN-ERROR MATCHING vs. TEMPERATURE 0.
PAGE 7
Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface PIN NAME FUNCTION 1 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. 2 CS Chip Select, active low.
PAGE 8
MAX199 Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface _______________Detailed Description Converter Operation The MAX199, a multi-range, fault-tolerant ADC, uses successive approximation and internal input track/hold (T/H) circuitry to convert an analog signal to a 12-bit digital output. The parallel-output format provides easy interface to microprocessors (µPs). Figure 3 shows the MAX199 in its simplest operational configuration.
PAGE 9
Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface Output Data Format The output data format is binary in unipolar mode and twos-complement binary in bipolar mode. When reading the output data, CS and RD must be low. When HBEN is low, the lower eight bits are read. When HBEN is high, the upper four MSBs are available and the output data bits D4–D7 are either set low (in unipolar mode) or set to the value of the MSB (in bipolar mode) (Table 5).
PAGE 10
MAX199 Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface Writing a new control byte during the conversion cycle will abort the conversion in progress and start a new acquisition interval. Table 5.
PAGE 11
Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface MAX199 tCSRS tCS tCSRH CS tCSWS tACQI tCSHW tWR tCONV WR tDH tDS D7–D0 CONTROL BYTE ACQMOD = "1" CONTROL BYTE ACQMOD = "0" tINT1 INT RD HBEN tD01 tD0 HIGH-Z HIGH / LOW BYTE VALID DOUT tTR HIGH / LOW BYTE VALID HIGH-Z Figure 6. Conversion Timing Using External Acquisition Mode Clock Modes The MAX199 operates with either an internal or an external clock.
PAGE 12
MAX199 Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface External Clock Mode Select external clock mode by writing the control byte with D7 = 0 and D6 = 0. Figure 8 shows CLK and WR timing relationships in internal and external acquisition modes, with an external clock. A 100kHz to 2.0MHz external clock with 45% to 55% duty cycle is required for proper operation.
PAGE 13
Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface Power-On Reset At power-up, the internal power-supply 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. Internal or External Reference The MAX199 can operate with either an internal or external reference.
PAGE 14
MAX199 Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface Power-Down Mode To save power, you can put the converter into lowcurrent shutdown mode between conversions. Two programmable power-down modes are available, in addition to a hardware shutdown. Select STBYPD or FULLPD by programming PD0 and PD1 in the input control byte. When software power-down is asserted, it becomes effective only after the end of conversion.
PAGE 15
Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface 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
MAX199 Multi-Range (±4V, ±2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface _________________________________________________________Functional Diagram REF CH7 CH6 CH5 CH4 CH3 CH2 CH1 CH0 REFADJ AV = 1.638 SIGNAL CONDITIONING BLOCK & OVERVOLTAGE TOLERANT MUX 10k +2.