Rainbow Electronics MAX126 User Manual

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________________General Description
The MAX125/MAX126 are high-speed, multichannel, 14-bit data-acquisition systems (DAS) with simultane­ous track/holds (T/Hs). These devices contain a 14-bit, 3µs, successive-approximation analog-to-digital con­verter (ADC), a +2.5V reference, a buffered reference input, and a bank of four simultaneous-sampling T/H amplifiers that preserve the relative phase information of the sampled inputs. The MAX125/MAX126 have two multiplexed inputs for each T/H, allowing a total of eight inputs. In addition, the converter is overvoltage tolerant to ±17V; a fault condition on any channel will not harm the IC. Available input ranges are ±5V (MAX125) and ±2.5V (MAX126).
An on-board sequencer converts one to four channels per CONVST pulse. In the default mode, one T/H output (CH1A) is converted. An interrupt signal (INT) is pro­vided after the last conversion is complete. Convert two, three, or four channels by reprogramming the MAX125/MAX126 through the bidirectional parallel interface. Once programmed, the MAX125/MAX126 continue to convert the specified number of channels per CONVST pulse until they are reprogrammed. The channels are converted sequentially, beginning with CH1. The INT signal always follows the end of the last conversion in a conversion sequence. The ADC con­verts each assigned channel in 3µs and stores the result in an internal 14x4 RAM. Upon completion of the conversions, data can be accessed by applying suc­cessive pulses to the RD pin. Four successive reads access four data words sequentially.
The parallel interface’s data-access and bus-release timing specifications are compatible with most popular digital signal processors and 16-bit/32-bit microproces­sors, so the MAX125/MAX126 conversion results can be accessed without resorting to wait states.
________________________Applications
Multiphase Motor Control Power-Grid Synchronization Power-Factor Monitoring Digital Signal Processing Vibration and Waveform Analysis
____________________________Features
Four Simultaneous-Sampling T/H Amplifiers with
Two Multiplexed Inputs (eight single-ended inputs total)
3µs Conversion Time per Channel Throughput: 250ksps (1 channel)
142ksps (2 channels) 100ksps (3 channels) 76ksps (4 channels)
Input Range: ±5V (MAX125)
±2.5V (MAX126)
Fault-Protected Input Multiplexer (±17V)±5V SuppliesInternal +2.5V or External Reference OperationProgrammable On-Board SequencerHigh-Speed Parallel DSP Interface
MAX125/MAX126
2x4-Channel, Simultaneous-Sampling
14-Bit DAS
________________________________________________________________
Maxim Integrated Products
1
19-1319; Rev 1; 1/98
PART
MAX125ACAX
MAX125BCAX 0°C to +70°C
0°C to +70°C
TEMP. RANGE PIN-PACKAGE
36 SSOP* 36 SSOP*
EVALUATION KIT
AVAILABLE
______________Ordering Information
*
Contact factory for availability.
Typical Operating Circuit appears at end of data sheet.
Pin Configuration appears at end of data sheet.
INL
(LSB)
±2 ±4
MAX125AEAX -40°C to +85°C 36 SSOP* ±2 MAX125BEAX -40°C to +85°C 36 SSOP* ±4
MAX125CCAX 0°C to +70°C 36 SSOP ±4
MAX125CEAX -40°C to +85°C 36 SSOP ±4 MAX126ACAX MAX126BCAX MAX126CCAX 0°C to +70°C
0°C to +70°C
0°C to +70°C 36 SSOP*
36 SSOP* 36 SSOP
±2 ±4
±4 MAX126AEAX -40°C to +85°C 36 SSOP* ±2 MAX126BEAX -40°C to +85°C 36 SSOP* ±4 MAX126CEAX -40°C to +85°C 36 SSOP ±4
MAX125
MAX125/MAX126
2x4-Channel, Simultaneous-Sampling 14-Bit DAS
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(AVDD= +5V ±5%, AVSS= -5V ±5%, DVDD= +5V ±5%, V
REFIN
= 2.5V, AGND = DGND = 0V, 4.7µF capacitor from REFOUT to
AGND, 0.1µF capacitor from REFIN to AGND, f
CLK
= 16MHz, external clock, 50% duty cycle, TA= 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.
AVDDto AGND ...........................................................-0.3V to 6V
AVSSto AGND............................................................0.3V to -6V
DVDDto DGND...........................................................-0.3V to 6V
AGND to DGND.......................................................-0.3V to 0.3V
CH_ _ to AGND....................................................................±17V
REFIN, REFOUT to AGND ..........................................-0.3V to 6V
Digital Inputs/Outputs to DGND ..............-0.3V to (DVDD+ 0.3V)
Continuous Power Dissipation (TA= +70°C)
SSOP (derate 11.8mW/°C above +70°C) .....................941mW
Operating Temperature Ranges
MAX125_CAX/MAX126_CAX...............................0°C to +70°C
MAX125_EAX/MAX126_EAX ............................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10sec)................................300°C
CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER
All channels 14NResolution MAX125A/MAX126A
Bits
±2
INL
Integral Nonlinearity (Note 2)
MAX12_B/C
LSB
±2 ±4
MAX12_A/B, guaranteed monotonic to 14 bits ±1
TA= +25°C
mV
±5 ±15
Bipolar Zero Error
TA= T
MIN
to T
MAX
±25
Bipolar Zero-Error Match Between all channels mV1.2 5
±5 ppm/°CZero-Code Tempco ±5 ±10
mVGain Error
±15TA= T
MIN
to T
MAX
TA= +25°C
1.2 5 mVGain Error Match ±5
Between all channels
Gain Error Tempco ppm/°C
72 75
SINAD
Single-channel mode, channel 1A, 250ksps
Signal-to-Noise Plus Distortion (Note 4)
dB
-89 -80THD Single-channel mode, channel 1A, 250ksps
Total Harmonic Distortion (Notes 4, 5)
dB
80 90SFDR Single-channel mode, channel 1A, 250ksps
Spurious-Free Dynamic Range (Note 4)
dB
80Single-channel mode, channel 1A, 250ksps
Channel-to-Channel Isolation (Note 6)
dB
MAX125C/MAX126C, guaranteed monotonic to 13 bits
LSB
±2
DNLDifferential Nonlinearity
DC ACCURACY (Note 1)
DYNAMIC PERFORMANCE (f
CLK
= 16MHz, fIN= 10.06kHz) (Notes 1, 3)
70 72
MAX125 MAX126
µA
MAX125/MAX126
2x4-Channel, Simultaneous-Sampling
14-Bit DAS
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(AVDD= +5V ±5%, AVSS= -5V ±5%, DVDD= +5V ±5%, V
REFIN
= 2.5V, AGND = DGND = 0V, 4.7µF capacitor from REFOUT to
AGND, 0.1µF capacitor from REFIN to AGND, f
CLK
= 16MHz, external clock, 50% duty cycle, TA= T
MIN
to T
MAX
, unless otherwise
noted.)
CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER
MAX125
V
±5
V
IN
Input Voltage Range
MAX125, VIN= ±5V
µA±667I
IN
Input Current
(Note 7) pF16C
IN
Input Capacitance
µs1t
ACQ
Acquisition Time
MHz8Small-Signal Bandwidth MHz0.5Full-Power Bandwidth
mV/ms2Droop Rate
ns5Aperture Delay
ps
RMS
30Aperture Jitter
ps500Aperture-Delay Matching
TA= +25°C V2.475 2.500 2.525V
REFOUT
Output Voltage
0mA < I
LOAD
< 1mA %±1External Load Regulation
(Note 9) ppm/°C30REFOUT Tempco
µF0.1
External Capacitive Bypass at REFIN
V2.50 ±10%Input Voltage Range
µF4.7 22
External Capacitive Bypass at REFOUT
REFIN = 2.5V µA±10Input Current (Note 10) k10Input Resistance (Note 7) pF10Input Capacitance
MHz0.1 16External Clock Frequency
V2.4V
IH
Input High Voltage
V0.8V
IL
Input Low Voltage
CONVST, RD, WR, CS, CLK
±1
(Note 7) pF15C
IN
Input Capacitance
A0–A3
µA
±10
I
IN
Input Current
MAX126 ±2.5
MAX126, VIN= ±2.5V
ANALOG INPUT
TRACK/HOLD
REFERENCE OUTPUT (Note 8)
REFERENCE INPUT
EXTERNAL CLOCK
DIGITAL INPUTS (CONVST, RD, WR, CS, CLK, A0–A3) (Note 1)
MAX125/MAX126
2x4-Channel, Simultaneous-Sampling 14-Bit DAS
4 _______________________________________________________________________________________
CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER
I
OUT
= 1mA V4V
OH
Output High Voltage
I
OUT
= -1.6mA V0.4V
OL
Output Low Voltage
D0–D13 µA±10Three-State Leakage Current (Note 7) pF10
Three-State Output Capacitance
V4.75 5 5.25AV
DD
Positive Supply Voltage
V-5.25 -5 -4.75AV
SS
Negative Supply Voltage
V4.75 5 5.25DV
DD
Digital Supply Voltage
mA17 25I(AVDD)Positive Supply Current mA-17 -13I(AVSS)Negative Supply Current mA3 5I(DVDD)Digital Supply Current mA3Shutdown Positive Current mA-1Shutdown Negative Current
mA3Shutdown Digital Current (Note 11) LSB±1 ±2PSRR+Positive Supply Rejection (Note 11) LSB±2PSRR-Negative Supply Rejection (Note 12) mW165 250Power Dissipation
DIGITAL OUTPUTS (D0–D13, INT) (Note 1)
POWER REQUIREMENTS
ELECTRICAL CHARACTERISTICS (continued)
(AVDD= +5V ±5%, AVSS= -5V ±5%, DVDD= +5V ±5%, V
REFIN
= 2.5V, AGND = DGND = 0V, 4.7µF capacitor from REFOUT to
AGND, 0.1µF capacitor from REFIN to AGND, f
CLK
= 16MHz, external clock, 50% duty cycle, TA= T
MIN
to T
MAX
, unless otherwise
noted.)
MAX125/MAX126
2x4-Channel, Simultaneous-Sampling
14-Bit DAS
_______________________________________________________________________________________ 5
CONDITIONS
ns30t
CW
CONVST Pulse Width
UNITSMIN TYP MAXSYMBOLPARAMETER
TIMING CHARACTERISTICS (Figure 4)
(AVDD= +5V, AVSS= -5V, DVDD= +5V, AGND = DGND = 0V, TA= T
MIN
to T
MAX
, unless otherwise noted.)
ns0t
CWS
CS to WR Setup Time
ns0t
CWH
CS to WR Hold Time
ns30t
WR
WR Low Pulse Width
ns125t
CSD
CS to CONVST Delay
ns30t
AS
Address Setup Time
ns0t
AH
Address Hold Time
25pF load ns30t
ID
RD to INT Delay
ns40t
RD
Delay Time Between Reads
ns0t
CRS
CS to RD Setup Time
ns0t
CRH
CS to RD Hold Time
ns30t
RD
RD Low Pulse Width
25pF load (Note 13) ns30t
DA
Data-Access Time
25pF load (Note 14) ns5 45t
DH
Bus-Relinquish Time
Mode 1, 1 channel
µs
3 Mode 2, 2 channel 6 Mode 3, 3 channel 9 Mode 4, 4 channel 12
t
CONV
Exiting shutdown µs5Start-Up Time
Note 1: AVDD= +5V, AVSS= -5V, DVDD= +5V, V
REFIN
= 2.500V (external), VIN= ±5V (MAX125) or ±2.5V (MAX126).
Note 2: Relative accuracy is the analog value’s deviation at any code from its theoretical value after the full-scale range has been
calibrated.
Note 3: CLK synchronized with CONVST. Note 4: f
IN
= 10.06kHz, VIN= ±5V (MAX125) or ±2.5V (MAX126).
Note 5: First five harmonics. Note 6: All inputs except CH1A driven with ±5V (MAX125) or ±2.5V (MAX126) 10kHz signal; CH1A connected to AGND and digitized. Note 7: Guaranteed by design. Not production tested. Note 8: AV
DD
= +5V, AVSS= -5V, DVDD= +5V, VIN= 0V (all channels).
Note 9: Temperature drift is defined as the change in output voltage from +25°C to T
MIN
or T
MAX
. It is calculated as
TC = [REFOUT/REFOUT] / T.
Note 10: See Figure 2. Note 11: Defined as the change in positive full scale caused by a ±5% variation in the nominal supply voltage. Tested with one input
at full scale and all others at AGND. V
REFIN
= 2.5V (internal).
Note 12: Tested with VIN= AGND on all channels, V
REFIN
= 2.5V (internal).
Note 13: The data-access time is defined as the time required for an output to cross 0.8V or 2.0V. It is measured using the circuit of
Figure 1. The measured number is then extrapolated back to determine the value with a 25pF load.
Note 14: The bus-relinquish time is derived from the measured time taken for the data outputs to change 0.5V when loaded with the
circuit of Figure 1. The measured number is then extrapolated back to remove the effects of charging/discharging the 120pF capacitor. Thus, the time given is the part’s true bus-relinquish time, independent of the external bus loading capacitance.
Conversion Time
Mode 1, 1 channel
ksps
250
Conversion Rate/Channel
Mode 2, 2 channel 142 Mode 3, 3 channel 100 Mode 4, 4 channel 76
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