MAX1253BEUE+T ,Stand-Alone, 10-Channel, 12-Bit System Monitors with Internal Temperature Sensor and VDD MonitorApplications Ordering InformationSystem SupervisionPART TEMP RANGE PIN-PACKAGERemote Telecom Networ ..
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MAX12555ETL+ ,14-Bit, 95Msps, 3.3V ADCfeatures a 300µW power-down mode to ±0.35V to ±1.10Vconserve power during idle periods.♦ Common-Mod ..
MAX12557ETK ,Dual, 65Msps, 14-Bit, IF/Baseband ADCApplications(Msps) (Bits)IF and Baseband Communication ReceiversMAX12557 65 14Cellular, LMDS, Point ..
MAX1257BETM ,2.5 V, 12-bit, multichannel ADC/DAC with FIFO, temperature sensing, and GPIO portFeaturesage from +2.7V to +3.6V (MAX1221/MAX1223/MAX1257)and from +4.75V to +5.25V (MAX1220/MAX1222 ..
MAX1257BETM+ ,12-Bit, Multichannel ADCs/DACs with FIFO, Temperature Sensing, and GPIO PortsGeneral Description Benefits and
MAX367CWN ,Signal-Line Circuit ProtectorsGeneral Description ________
MAX367EWN ,Signal-Line Circuit ProtectorsFeaturesThe MAX366 and MAX367 are multiple, two-terminal circuit' ±40V Overvoltage Protectionprotec ..
MAX367EWN ,Signal-Line Circuit ProtectorsApplicationsMAX367 available after January 1, 1995.* Dice are tested at T = +25°C only.Process Cont ..
MAX367EWN+ ,Signal Line Circuit Protector with Three Independent ProtectorsMAX366/MAX36719-0326; Rev 0; 12/94Signal-Line Circuit Protectors_______________
MAX3680EAI ,+3.3V / 622Mbps / SDH/SONET 1:8 Deserializer with TTL OutputsELECTRICAL CHARACTERISTICS(V = +3.0V to +3.6V, T = -40°C to +85°C, unless otherwise noted. Typical ..
MAX3680EAI ,+3.3V / 622Mbps / SDH/SONET 1:8 Deserializer with TTL OutputsApplications622Mbps SDH/SONET Transmission Systems________________Ordering Information622Mbps ATM/S ..
MAX1253BEUE+T
Stand-Alone, 10-Channel, 12-Bit System Monitors with Internal Temperature Sensor and VDD Monitor
General DescriptionThe MAX1253/MAX1254 are stand-alone, 10-channel (8
external, 2 internal) 12-bit system monitor ADCs with
internal reference. A programmable single-ended/dif-
ferential mux accepts voltage and remote-diode tem-
perature-sensor inputs. These devices independently
monitor the input channels without microprocessor
interaction and generate an interrupt when any variable
exceeds user-defined limits. The MAX1253/MAX1254
configure both high and low limits, as well as the num-
ber of fault cycles allowed, before generating an inter-
rupt. These ADCs can also perform recursive data
averaging for noise reduction. Programmable wait inter-
vals between conversion sequences allow the selection
of the sample rate.
At the maximum sampling rate of 94ksps (auto mode,
single channel enabled), the MAX1253 consumes only
5mW (1.7mA at 3V). AutoShutdownTMreduces supply
current to 190µA at 2ksps and to less than 8µA at 50sps.
Stand-alone operation, combined with ease of use in a
small package (16-pin TSSOP), makes the MAX1253/
MAX1254 ideal for multichannel system-monitoring
applications. Low power consumption also makes
these devices a good fit for hand-held and battery-pow-
ered applications.
ApplicationsSystem Supervision
Remote Telecom Networks
Server Farms
Remote Data Loggers
FeaturesMonitor 10 Signals Without ProcessorInterventionEight External Channels Programmable as
Temperature or Voltage MonitorsIntelligent Circuitry for Reliable AutonomousMeasurement
Programmable Digital Averaging FilterProgrammable Fault CounterPrecision Measurements12-Bit Resolution
±1 LSB INL, ±1 LSB DNL±0.75°C Temperature Accuracy (typ)Flexible
Automatic Channel Scan Sequencer withProgrammable Intervals
Programmable Inputs: Single Ended/Differential,Voltage/Temperature
Programmable Wait StateInternal 2.5V/4.096V Reference(MAX1253/MAX1254)Remote Temperature Sensing Up to 10m(Differential Mode)Single 3V or 5V Supply OperationSmall 16-Pin TSSOP Package
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitor
Selector Guide19-2838; Rev 0; 4/03
*Future product—contact factory for availability.
*Future product—contact factory for availability.
Typical Application Circuit appears at end of data sheet.AutoShutdown is a trademark of Maxim Integrated Products, Inc.
PARTINL (LSB)TEMP
ERROR (°C)
SUPPLY
VOLTAGE (V)MAX1253AEUE*±1±1.02.7 to 3.6
MAX1253BEUE±1±3.02.7 to 3.6
MAX1254AEUE*±1±1.04.5 to 5.5
MAX1254BEUE±1±2.54.5 to 5.5
AIN0
SCLK
DIN
VDD
GND
DOUT
INT
REF
TOP VIEW
MAX1253
MAX1254
16 TSSOPAIN1
AIN2
AIN5
AIN3
AIN4
AIN6
AIN7
Pin Configuration
Ordering Information
PARTTEMP RANGEPIN-PACKAGE
MAX1253AEUE*-40°C to +85°C16 TSSOP
MAX1253BEUE-40°C to +85°C16 TSSOP
MAX1254AEUE*-40°C to +85°C16 TSSOP
MAX1254BEUE-40°C to +85°C16 TSSOP
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitor
ABSOLUTE MAXIMUM RATINGSStresses 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.
VDDto GND.............................................................-0.3V to +6V
Analog Inputs to GND (AIN0–AIN7, REF) ...-0.3V to (VDD+ 0.3V)
Digital Inputs to GND (DIN, SCLK, CS) ....-0.3V to (VDD+ 0.3V)
Digital Outputs to GND (DOUT, INT) ........-0.3V to (VDD+ 0.3V)
Digital Outputs Sink Current .............................................25mA
Maximum Current into Any Pin ..........................................50mA
Continuous Power Dissipation (TA= +70°C)
16-Pin TSSOP (derate 8.7mW/°C above +70°C).........696mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
DC ACCURACYResolutionRES12Bits
Grade A±1.0Integral Nonlinearity (Note 1)INLGrade B±1.0LSB
Differential NonlinearityDNLNo missing codes overtemperature±1.0LSB
Offset Error±4.0LSB
External reference±4.0LSBGain Error (Note 2)Internal reference2.0%FSR
Offset Error Tempco±5p p m /°C
External reference±2Gain and Temperature CoefficientInternal reference±30p p m /°C hannel - to- C hannel Offset M atchi ng ±0.1LSBDD M oni tor Accur acyInternal reference±2.5%
DYNAMIC ACCURACY(10kHz sine-wave input, 2.5VP-P (MAX1253), 4.096VP-P (MAX1254), 64ksps, fSCLK = 10MHz, bipolar input mode)
Signal-to-Noise Plus DistortionSINAD70dB
Total Harmonic DistortionTHDUp to the 5th harmonic-76dB
Spurious-Free Dynamic RangeSFDR72dB
Full-Power Bandwidth-3dB point1MHz
Full Linear BandwidthS / (N + D) > 68dB100kHz
CONVERSION RATEVoltage measurement, all ref modes10.611.7
Temp-sensor ref modes 01, 104650.7Conversion Time (Note 3)tCONV
Temp-sensor ref mode 007380
Single-Channel ThroughputManual trigger, voltage measurement70ksps
Power-Up TimetPUInternal reference (Note 4)4045µs
ANALOG INPUT (AIN0–AIN7)ni p ol ar , si ng l e- end ed , or d i ffer enti al i np uts0+VREFInput Voltage Range (Note 5)Bipolar, differential inputs-VREF / 2+VREF / 2V
Common-Mode RangeDifferentially configured inputs0VDDV
Common-Mode RejectionD i ffer enti all y confi g ur ed i np uts, V C M = 0 to V D D -90dB
ELECTRICAL CHARACTERISTICS(VDD= +2.7V to +3.6V (MAX1253), VDD= +4.5V to +5.5V (MAX1254), VREF= +2.5V (MAX1253), VREF= +4.096V (MAX1254), fSCLK
= 10MHz (50% duty cycle), TA= TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitor
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSInput Leakage CurrentOn-/off-leakage, VIN = 0 or VDD±1µA
Input Capacitance(Note 6)18pF
TEMPERATURE MEASUREMENTSTA = -20°C to +85°C±0.5±1.0
TA = -40°C to +85°C±0.75±1.5
Grade A
MAX1253
MAX1254TA = +25°C±0.3
TA = -40°C to +85°C±1.2±2.5Grade B
MAX1253TA = +25°C±0.7
TA = -40°C to +85°C±1.2±3.0
Internal Sensor Measurement Error
(Note 7)
Grade B
MAX1254TA = +25°C±0.7
TA = -40°C to +85°C±2DifferentialTA = +25°C±1
TA = -40°C to +85°C±5
External Sensor Measurement
Error (Note 8)Single endedTA = +25°C±2
Differentially configured inputs and internal
sensor0.3Temperature Measurement Noise
Single-ended configured, external sensor0.1
Temperature Resolution0.125°C/LSB
Low4External Sensor Bias CurrentHigh66µA
Differentially configured inputs and internal
sensor0.3Power-Supply RejectionPSR
Single-ended configured, external sensor0.1
°C/V
INTERNAL REFERENCEMAX12532.4562.5002.544REF Output VoltageVREFMAX12544.0244.0964.168V
Grade A±8REF Temperature CoefficientTCREFGrade B±30p p m /°C
REF Output Resistance7kΩ
MAX1253200REF Output NoiseMAX1254160µVRMS
MAX1253-70-50REF Power-Supply Rejection RatioPSRRMAX1254-70-50dB
EXTERNAL REFERENCEREF Input Voltage RangeVREF1.0 VDD + 0.05V
VREF = +2.5V; fSAMPLE = 94ksps1540REF Input CurrentIREFIn power-down±1µA
ELECTRICAL CHARACTERISTICS (continued)(VDD= +2.7V to +3.6V (MAX1253), VDD= +4.5V to +5.5V (MAX1254), VREF= +2.5V (MAX1253), VREF= +4.096V (MAX1254), fSCLK
= 10MHz (50% duty cycle), TA= TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitor
ELECTRICAL CHARACTERISTICS (continued)(VDD= +2.7V to +3.6V (MAX1253), VDD= +4.5V to +5.5V (MAX1254), VREF= +2.5V (MAX1253), VREF= +4.096V (MAX1254), fSCLK
= 10MHz (50% duty cycle), TA= TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
DIGITAL INPUTS (SCLK, DIN, CS)Input Voltage LowVIL VDD x 0.3V
Input Voltage HighVIHVDD x 0.7V
Input HysteresisVHYST200mV
Input Leakage CurrentIINVIN = 0 or VDD±10µA
Input CapacitanceCIN2pF
DIGITAL OUTPUTS (INT, DOUT)ISINK = 8mA, DOUT0.5Output Voltage LowVOLISINK = 2mA, INT0.5V
ISOURCE = 8mA, DOUTVDD - 0.5Output Voltage HighVOHISOURCE = 2mA, INTVDD - 0.5V
Tri-State Leakage CurrentILCS = VDD±10µA
Tri-State Output CapacitanceCOUTCS = VDD5pF
POWER REQUIREMENTSMAX12532.73.6Positive Supply VoltageVDDMAX12544.55.5V
MAX1253 internal reference (Note 9)3.3
MAX1253 internal reference (Note 10)2.9
MAX1253 external reference (Note 10)2.2
MAX1254 internal reference (Note 9)5.0
MAX1254 internal reference (Note 10)4.0
MAX1254 external reference (Note 10)3.0Supply CurrentIDD
Both internal reference, mode 01 (Note 11)8µA
MAX1253480Full Power-Down Supply CurrentISHDNFull power-down stateMAX1254860nA
Power-Supply Rejection RatioPSRRAnalog inputs at full scale (Note 12)±0.4±1.6mV/V
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitor
Note 1:Relative accuracy is the deviation of the analog value at any code from its theoretical value after the gain and offset errors
have been calibrated.
Note 2:Offset nulled.
Note 3:In reference mode 00, the reference system powers up for each temperature measurement. In reference mode 01, the ref-
erence system powers up once per sequence of channels scanned. If a sample wait <80µs is programmed, the reference
system is on all the time. In reference mode 10, the reference system is on all the time (see Table 7).
Note 4:No external capacitor on REF.
Note 5:The operational input voltage range for each individual input of a differentially configured pair (AIN0–AIN7) is from GND to
VDD. The operational input voltage difference is from -VREF/2 to +VREF/2.
Note 6:See Figure 3 and the Sampling Error vs. Input Source Impedance graph in the Typical Operating Characteristicssection.
Note 7:Grade A tested at +10°C and +55°C. -20°C to +85°C and -40°C to +85°C specifications guaranteed by design. Grade B
tested at +25°C. TMINto TMAXspecification guaranteed by design.
Note 8:External temperature measurement mode using an MMBT3904 (Diodes Inc.) as a sensor. External temperature sensing
from -40°C to +85°C; MAX1253/MAX1254 held at +25°C.
Note 9:Performing eight single-ended external channels’ temperature measurements, an internal temperature measurement, and
an internal VDDmeasurement with no sample wait results in a conversion rate of 2ksps per channel.
Note 10:Performing eight single-ended voltage measurements, an internal temperature measurement, and an internal VDDmeasure-
ment with no sample wait results in a conversion rate of 7ksps per channel.
Note 11:Performing eight single-ended voltage measurements, an internal temperature measurement, and an internal VDDmeasure-
ment with maximum sample wait results in a conversion rate of 3ksps per channel.
Note 12:Defined as the shift in the code boundary as a result of supply voltage change. VDD= min to max; full-scale input, mea-
sured using external reference.
TIMING CHARACTERISTICS(VDD= +2.7V to +3.6V (MAX1253), VDD= +4.5V to +5.5V (MAX1254), TA= TMINto TMAX, unless otherwise noted.) (Figures 1, 2, and 4)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSCLK Clock PeriodtCP1000.5ns
SCLK Pulse Width High TimetCH45ns
SCLK Pulse Width Low TimetCL45ns
DIN to SCLK Setup TimetDS25ns
DIN to SCLK Hold TimetDH0ns
CS Fall to SCLK Rise SetuptCSS25ns
SCLK Rise to CS Rise HoldtCSH50ns
SCLK Fall to DOUT ValidtDOVCL = 30pF50ns
CS Rise to DOUT DisabletDODCL = 30pF40ns
CS Fall to DOUT EnabletDOECL = 30pF40ns
CS Pulse Width HightCSW40ns
SUPPLY CURRENT
vs. SAMPLE RATEMAX1253/54 toc07
SAMPLE RATE (kHz)
SUPPLY CURRENT (mA)10.10.01
INTERNAL REFERENCE
(MODE 01) MAX1254
9 TEMPERATURE
CHANNELS AND 1
VOLTAGE CHANNEL
9 VOLTAGE
CHANNELS AND
1 TEMPERATURE
CHANNEL
1 VOLTAGE CHANNEL
(VDD/2)
SUPPLY CURRENT
vs. SUPPLY VOLTAGEMAX1253/54 toc08
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
EXTERNAL REFERENCE (MODE 00)
9 VOLTAGE CHANNELS AND
1 TEMPERATURE CHANNEL
1 VOLTAGE CHANNEL
(VDD/2)
9 TEMPERATURE CHANNELS
AND 1 VOLTAGE CHANNEL
REFERENCE VOLTAGE
vs. TEMPERATUREMAX1253/54 toc05
TEMPERATURE (°C)
REFERENCE VOLTAGE (V)40200-20
GRADE A
GRADE B
MAX1253
REFERENCE VOLTAGE
vs. TEMPERATUREMAX1253/54 toc05b
TEMPERATURE (°C)
REFERENCE VOLTAGE (V)40200-20
GRADE A
MAX1254
GRADE B
SUPPLY CURRENT
vs. SAMPLE RATEMAX1253/54 toc06
SAMPLE RATE (kHz)
SUPPLY CURRENT (mA)10.10.01
INTERNAL REFERENCE
(MODE 01) MAX1253
9 TEMPERATURE
CHANNELS AND 1
VOLTAGE CHANNEL
(VDD/2)
9 VOLTAGE
CHANNELS AND
1 TEMPERATURE
CHANNEL
1 VOLTAGE CHANNEL
(VDD/2)
INTERNAL REFERENCE VOLTAGE
vs. SUPPLY VOLTAGEMAX1253/54 toc04
SUPPLY VOLTAGE (V)
INTERNAL REFERENCE VOLTAGE (V)
MAX1254
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitor
Typical Operating Characteristics(VDD= +3V, VREF= 2.5V (MAX1253); VDD= 5V, VREF= 4.096V (MAX1254); fSCLK= 10MHz, CREF= 0.1µF, TA= +25°C, unless oth-
erwise noted.)
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODEMAX1253/54 toc01
OUTPUT CODE
INL (LSB)
DIFFERENTIAL NONLINEARITY
vs. DIGITAL OUTPUT CODE
MAX1253/54 toc02
OUTPUT CODE
DNL (LSB)
INTERNAL REFERENCE VOLTAGE
vs. SUPPLY VOLTAGE
MAX1253/54 toc03
SUPPLY VOLTAGE (V)
INTERNAL REFERENCE VOLTAGE (V)
MAX1253
GAIN ERROR vs. TEMPERATUREMAX1253/54 toc15
TEMPERATURE (°C)
GAIN ERROR (LSB)655035205-10-25
UNIPOLAR
DIFFERENTIAL
CONFIGURATION
EXTERNAL
REFERENCE MODE
BIPOLAR DIFFERENTIAL
CONFIGURATION
EXTERNAL REFERENCE
MODE
UNIPOLAR SINGLE-ENDED
CONFIGURATION
EXTERNAL REFERENCE MODE
OFFSET ERROR vs. TEMPERATUREMAX1253/54 toc16
TEMPERATURE (°C)
OFFSET ERROR (LSB)655035205-10-25
UNIPOLAR
DIFFERENTIAL
CONFIGURATION
EXTERNAL
REFERENCE MODE
BIPOLAR DIFFERENTIAL
CONFIGURATION
EXTERNAL REFERENCE
MODE
UNIPOLAR SINGLE-ENDED
CONFIGURATION
EXTERNAL REFERENCE
MODE
INTERNAL TEMPERATURE SENSOR
TEMPERATURE ERRORMAX1253/54 toc17
TEMPERATURE (°C)
ERROR (40200-20
MAX1253/MAX1254
GRADE A INTERNAL
SENSOR
GRADE B INTERNAL
SENSOR
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitorypical Operating Characteristics (continued)(VDD= +3V, VREF= 2.5V (MAX1253); VDD= 5V, VREF= 4.096V (MAX1254); fSCLK= 10MHz, CREF= 0.1µF, TA= +25°C, unless oth-
erwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGEMAX1253/54 toc09
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
INTERNAL REFERENCE (MODE 01)
9 TEMPERATURE CHANNELS
AND VOLTAGE CHANNEL (VDD/2)
9 VOLTAGE
CHANNELS AND
1 TEMPERATURE
CHANNEL
1 VOLTAGE
CHANNEL (VDD/2)
SUPPLY CURRENT
vs. TEMPERATUREMAX1253/54 toc10
TEMPERATURE (°C)
SUPPLY CURRENT (mA)653550-10520-25
9 TEMPERATURE CHANNELS AND
1 VOLTAGE CHANNEL (VDD/2)
9 VOLTAGE CHANNELS AND
1 TEMPERATURE CHANNEL
1 VOLTAGE CHANNEL (VDD/2)
INTERNAL REFERENCE (MODE 01) MAX1253
SUPPLY CURRENT
vs. TEMPERATUREMAX1253/54 toc11
TEMPERATURE (°C)
SUPPLY CURRENT (mA)653550-10520-25
9 TEMPERATURE CHANNELS AND
1 VOLTAGE CHANNEL (VDD/2)
9 VOLTAGE CHANNELS AND
1 TEMPERATURE CHANNEL
1 VOLTAGE CHANNEL (VDD/2)
INTERNAL REFERENCE (MODE 01) MAX1254
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGEMAX1253/54 toc12
SUPPLY VOLTAGE (V)
SHUTDOWN SUPPLY CURRENT (nA)
MAX1253
MAX1254
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATUREMAX1253/54 toc13
TEMPERATURE (°C)
SHUTDOWN SUPPLY CURRENT (nA)5035205-10-25
MAX1254
VDD = 5V
MAX1253
VDD = 3V
GAIN AND OFFSET ERROR
vs. SUPPLY VOLTAGEMAX1253/54 toc14
SUPPLY VOLTAGE (V)
GAIN AND OFFSET ERROR (LSB)
SINGLE ENDED
MAX1253
MAX1254
OFFSET ERROR
GAIN ERROR
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitor
EXTERNAL TEMPERATURE SENSOR
TEMPERATURE ERRORMAX1253/54 toc18
TEMPERATURE (°C)
ERROR (40200-20
MAX1253/MAX1254
EXTERNAL SENSOR,
DIFFERENTIAL INPUT
EXTERNAL SENSOR,
SINGLE-ENDED INPUT
TEMPERATURE ERROR vs. INTERCONNECT
CAPACITANCE (EXTERNAL SENSOR)MAX1253/54 toc19
INTERCONNECT CAPACITANCE (pF)
TEMPERATURE (
°C)101001000
EXTERNAL DIODE
DIFFERENTIAL TEMPERATURE
MEASUREMENT MODE
SAMPLING ERROR
vs. INPUT SOURCE IMPEDANCEMAX1253/54 toc20
SOURCE IMPEDANCE (Ω)
SAMPLING ERROR (LSB)
100010010,000
TURN ON THERMAL TRANSIENT,
CONTINUOUS CONVERSION
VDD = 3.0VMAX1253/54 toc21
TIME (s)
TEMPERATURE SHIFT (2015105
IN A TSSOP SOCKET
SOLDER ON A 2in ✕ 2in PWB
IN AN OIL BATH
EXTERNAL BJT
Typical Operating Characteristics (continued)(VDD= +3V, VREF= 2.5V (MAX1253); VDD= 5V, VREF= 4.096V (MAX1254); fSCLK= 10MHz, CREF= 0.1µF, TA= +25°C, unless oth-
erwise noted.)
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitor
Pin Description
PINNAMEFUNCTIONAIN0Analog Voltage Input/Temperature Input Channel 0 or Positive Differential Input Relative to AIN1AIN1Analog Voltage Input/Temperature Input Channel 1 or Negative Differential Input Relative to AIN0AIN2Analog Voltage Input/Temperature Input Channel 2 or Positive Differential Input Relative to AIN3AIN3Analog Voltage Input/Temperature Input Channel 3 or Negative Differential Input Relative to AIN2AIN4Analog Voltage Input/Temperature Input Channel 4 or Positive Differential Input Relative to AIN5AIN5Analog Voltage Input/Temperature Input Channel 5 or Negative Differential Input Relative to AIN4AIN6Analog Voltage Input/Temperature Input Channel 6 or Positive Differential Input Relative to AIN7AIN7Analog Voltage Input/Temperature Input Channel 7 or Negative Differential Input Relative to AIN6REFPositive Reference Input in External Mode. Bypass REF with a 0.1µF capacitor to GND when in external mode.
When using the internal reference, REF must be left open.INTInterrupt Output. Push-pull or open drain with selectable polarity. See Table 9 and the INT Interrupt Output section.DOUTSerial Data Output. DOUT transitions on the falling edge of SCLK. High impedance when CS is at logic high.GNDGroundVDDPositive Power Supply. Bypass with a 0.1µF capacitor to GND.DINSerial Data Input. DIN data is latched into the serial interface on the rising edge of the SCLK.SCLKSerial Clock Input. Clocks data in and out of the serial interface (duty cycle must be 40% to 60%).CSActive-Low Chip-Select Input. When CS is low, the serial interface is enabled. When CS is high, DOUT is high
impedance, and the serial interface resets.
ACCUMULATOR
INTERNAL TEMPUPPER
THRESHOLD
LOWER
THRESHOLD
CHANNEL
CONFIGURATION
ACCUMULATOR
VDD/2UPPER
THRESHOLD
LOWER
THRESHOLD
CHANNEL
CONFIGURATION
ACCUMULATOR
AIN0UPPER
THRESHOLD
LOWER
THRESHOLD
CHANNEL
CONFIGURATION
ACCUMULATOR
AIN1UPPER
THRESHOLD
LOWER
THRESHOLD
CHANNEL
CONFIGURATION
ACCUMULATOR
AIN2UPPER
THRESHOLD
LOWER
THRESHOLD
CHANNEL
CONFIGURATION
ACCUMULATOR
AIN3UPPER
THRESHOLD
LOWER
THRESHOLD
CHANNEL
CONFIGURATION
ACCUMULATOR
AIN4UPPER
THRESHOLD
LOWER
THRESHOLD
CHANNEL
CONFIGURATION
ACCUMULATOR
AIN5UPPER
THRESHOLD
LOWER
THRESHOLD
CHANNEL
CONFIGURATION
ACCUMULATOR
AIN6UPPER
THRESHOLD
LOWER
THRESHOLD
CHANNEL
CONFIGURATION
ACCUMULATOR
AIN7UPPER
THRESHOLD
LOWER
THRESHOLD
CHANNEL
CONFIGURATION
AIN7
AIN6
AIN5
AIN4
AIN3
AIN2
AIN1
VDD
MUX
TEMP
SENSOR
REFERENCE
12-BIT
ADC WITH
T/H
SCAN
AND
CONVERSION
CONTROL
PORPOWER-
GOOD
INPUT CHANNEL REGISTER
INPUT CONFIGURATION REGISTER
STEP-UP REGISTER
ALARM REGISTER
AVERAGING
DIGITAL
COMPARATOR
SERIAL
INTERFACE
REF
DOUT
DIN
SCLK
INT
MAX1253
MAX1254
Block Diagram
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitorGND
a) VOL TO VOH
CLOAD = 100pF100nA
DOUT
GND
VDD
b) HIGH-Z TO VOL AND VOH TO VOL
CLOAD = 100pF
100nA
DOUT
Figure 1. Load Circuits for DOUT Enable Time and SCLK to
DOUT Delay Time
GND
a) VOH TO HIGH-Z
CLOAD = 100pF100nA
DOUT
GND
VDD
b) VOL TO HIGH-Z
CLOAD = 100pF
100nA
DOUT
Figure 2. Load Circuit for DOUT Disable Time
Detailed DescriptionThe MAX1253/MAX1254 are precision-monitoring inte-
grated circuit systems specifically intended for stand-
alone operation. They can monitor diverse types of
inputs, such as those from temperature sensors and
voltage signals from pressure, vibration, and accelera-
tion sensors, and digitize these input signals. The digi-
tal values are then compared to preprogrammed
thresholds and, if the thresholds are exceeded, the
processor is alerted by an interrupt signal. No interac-
tion by the CPU or microcontroller (µC) is required until
one of the programmed limits is exceeded (Figures 3
and 4).
Voltages on all the inputs are converted to 12-bit values
sequentially and stored in the current data registers.
Note that eight of these inputs are external and two are
internal. One of the internal inputs monitors the VDD
voltage supply, while the other monitors the internal IC
temperature. AIN0 to AIN7 can be configured as either
single ended (default) or differential. In addition, these
inputs can be configured for single-ended or differen-
tial temperature measurements. In the temperature
configuration, the device provides the proper bias nec-
essary to measure temperature with a diode-connected
transistor sensor. The user enables which inputs are
measured (both external and internal) and sets the
delay between each sequence of measurements dur-
ing the initial setup of the device.
The values stored in the current data registers are com-
pared to the user-preprogrammed values in the thresh-
old registers (upper and lower thresholds) and, if
exceeded, activate the interrupt output and generate an
alarm condition. If desired, the device can be pro-
grammed to average the results of many measurements
before comparing to the threshold value. This reduces
the sensitivity to external noise in the measured signal.
In addition, the user can set the number of times the
threshold is exceeded (fault cycles) before generating
an interrupt. This feature reduces falsely triggered
alarms caused by undesired, random spurious impulses.
When the fault cycle criterion is exceeded, an alarm
condition is created. The device writes the fault condi-
tion into the alarm register to indicate the alarmed input
channel.
Converter OperationThe MAX1253/MAX1254 ADCs use a fully differential
successive-approximation register (SAR) conversion
technique and an on-chip track-and-hold (T/H) block to
convert temperature and voltage signals into a 12-bit
digital result. Both single-ended and differential config-
urations are supported with a unipolar signal range for
single-ended mode and bipolar or unipolar ranges for
differential mode. Figure 5 shows the equivalent input
circuit for the MAX1253/MAX1254. Configure the input
channels according to Tables 5 and 6 (see the Input
Configuration Registersection).
In single-ended mode, the positive input (IN+) is con-
nected to the selected input channel and the negative
input (IN-) is connected to GND. In differential mode,
IN+ and IN- are selected from the following pairs:
AIN0/AIN1, AIN2/AIN3, AIN4/AIN5, and AIN6/AIN7.
Once initiated, voltage conversions require 10.6µs (typ)
to complete.
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitorDuring the acquisition interval, IN+ and IN- charge both
a positive (CHOLDP) and a negative (CHOLDN) sam-
pling capacitor. After completing the acquisition inter-
val, the T/H switches open, storing an accurate sample
of the differential voltage between IN+ and IN-. This
charge is then transferred to the ADC and converted.
Finally, the conversion result is transferred to the cur-
rent data register.
Temperature conversions require 46µs (typ) and mea-
sure the difference between two sequential voltage
measurements (see the Temperature Measurement
section for a detailed description).
Fully Differential Track/Hold (T/H)The T/H acquisition interval begins with the rising edge
of CS(for manually triggered conversions) and is inter-
nally timed to 1.5µs (typ). The accuracy of the input sig-
nal sample is a function of the input signal’s source
impedance and the T/H’s capacitance. In order to
achieve adequate settling of the T/H, limit the signal
source impedance to a maximum of 1kΩ.
Input BandwidthThe ADC’s input tracking circuitry has a 1MHz small-
signal bandwidth. To avoid high-frequency signals
aliasing into the frequency band of interest, anti-alias
prefiltering of the input signals is recommended.
Analog Input ProtectionInternal protection diodes, which clamp the analog
inputs to VDDand GND, allow the channel input pins to
swing from (GND - 0.3V) to (VDD+ 0.3V) without dam-
age. However, for accurate conversions near full scale,
the inputs must not exceed VDDby more than 50mV or
be lower than GND by 50mV. If the analog input range
must exceed 50mV beyond the supplies, limit the input
current.
Single Ended/DifferentialThe MAX1253/MAX1254 use a fully differential ADC for
all conversions. Through the input configuration regis-
ter, the analog inputs can be configured for either dif-
ferential or single-ended conversions. When sampling
signal sources close to the MAX1253/MAX1254, single-
ended conversion is generally sufficient. Single-ended
conversions use only one analog input per signal
source, internally referenced to GND.
MUX
AIN0
VDD
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AIN7
TEMP
SENSE
12-BIT
ADC WITH T/H
DIGITAL
COMPARATOR
INPUT REGISTERS
CURRENT DATA
UPPER THRESHOLD
LOWER THRESHOLD
# FAULT CYCLES
AVERAGE
CONFIGURATION/
STATUS
REGISTERS
SCAN AND
CONVERSION
CONTROL
SERIAL
INTERFACE
DIN
INT
DOUT
SCLK
Figure 3. Simplified Alarm Block Diagram of the MAX1253/MAX1254
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitorIS CHANNEL
ENABLED
SAMPLE
CHANNEL
AVERAGE
CONVERTED
CHANNEL DATA
AVG DATA
> UPPER
SAME FAULT
AS PREVIOUS
RESET FAULT
COUNTER
INCREMENT
FAULT COUNTER
AVG DATA
< LOWER
INCREMENT
CHANNEL
COUNTER
FAULT CNT
FAULT REG
SET ALARM
REGISTER
YES
CONVERT
CHANNEL
YES
YES
YES
YES
Figure 4. Alarm Flowchart
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitorIn differential mode, the T/H samples the difference
between two analog inputs, eliminating common-mode
DC offsets and noise. See the Input Configuration
Registersection and Tables 5 and 6 for more details on
configuring the analog inputs.
Unipolar/BipolarWhen performing differential conversions, the input
configuration register (Tables 5 and 6) also selects
between unipolar and bipolar operation. Unipolar mode
sets the differential input range from 0 to VREF. A nega-
tive differential analog input in unipolar mode causes
the digital output code to be zero. Selecting bipolar
mode sets the differential input range to ±VREF/2. The
digital output code is straight binary in unipolar mode
and two’s complement in bipolar mode (see the
Transfer Functionsection).
In single-ended mode, the MAX1253/MAX1254 always
operate in unipolar mode. The analog inputs are inter-
nally referenced to GND with a full-scale input range
from 0 to VREF.
Digital InterfaceThe MAX1253/MAX1254 digital interface consists of
five signals: CS, SCLK, DIN, DOUT, and INT. CS,
SCLK, DIN, and DOUT comprise an SPI™-compatible
serial interface (see the Serial Digital Interfacesection).
INT is an independent output that provides an indica-
tion that an alarm has occurred in the system (see the
INT Interrupt Outputsection).
Serial Digital InterfaceThe MAX1253/MAX1254 feature a serial interface com-
patible with SPI, QSPI™, and MICROWIRE™ devices.
For SPI/QSPI, ensure that the CPU serial interface runs
in master mode so it generates the serial clock signal.
Select a serial clock frequency of 10MHz or less, and
set clock polarity (CPOL) and phase (CPHA) in the µP
control registers to the same value, one or zero. The
MAX1253/MAX1254 support operation with SCLK idling
high or low, and thus operate with CPOL = CPHA = 0 or
CPOL = CPHA = 1.
VAZ
VDD
ADC
CHOLDPCHOLD
CHOLDN
8-TO-1
DIFFERENTIAL
MUX
TEMP
DIFFERENTIAL INPUT EQUIVALENT INPUT CIRCUIT
VAZ
VDD
ADC8-TO-1
DIFFERENTIAL
MUX
TEMP
SINGLE-ENDED INPUT EQUIVALENT INPUT CIRCUIT
Figure 5. Single-Ended/Differential Input Equivalent Input Circuit
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitorClock pulses on SCLK shift data into DIN on the rising
edge of the SCLK and out of DOUT on the falling edge
of SCLK.
Data transfers require a logic low on CS. A high-to-low
transition of CSmarks the beginning of a data transfer. A
logic high on CSat any time resets the serial interface.
See Figure 6 and the Timing Characteristicstable for
detailed serial-interface timing information.
Input Data FormatSerial communications always begin with an 8-bit com-
mand word, serially loaded from DIN. A high-to-low
transition on CSinitiates the data input operation. The
command word and the subsequent data bytes (for
write operations) are clocked from DIN into the
MAX1253/MAX1254 on the rising edges of SCLK. The
first rising edge on SCLK, after CSgoes low, clocks in
the MSB of the command word (see the Command
Wordsection). The next seven rising edges on SCLK
complete the loading of the command word into the
internal command register. After the 8-bit command
word is entered, transfer 0 to 20 bytes of data, depend-
ing on the command. Table 2 shows the number of
data bytes for each command.
Output Data FormatOutput data from the MAX1253/MAX1254 is clocked
onto DOUT on the falling edge of SCLK. Single-ended
and unipolar differential measurements are output in
straight binary MSB first, with two 8-bytes-per-conver-
sion result, and the last 4 bits padded with zeros. For
temperature and bipolar differential voltage measure-
ments, the output is two’s complement binary in the
same 2-byte format. The MSB of the output data from a
read command transitions at DOUT after the falling
edge of the 8th SCLK clock pulse following the CS
high-to-low transition. Table 2 shows the number of
bytes to be read from DOUT for a given read com-
mand.
Command WordThe command word (Table 1) controls all serial com-
munications and configuration of the MAX1253/
MAX1254, providing access to the 44 on-chip registers.
The first 4 MSBs of the command word specify the
command (Table 2), while the last 4 bits provide
address information.
The first rising edge on SCLK, after CSgoes low, trans-
fers the command word MSB into DIN. The next seven
rising edges on SCLK shift the remaining 7 bits into the
internal command register (see the Serial Digital
Interfacesection).
HIGH-ZHIGH-Z
tCSS
tDOE
tDS
tDH
tCHtCLtCP
tDOVtDOD
tCSH
tCSW
SCLK
DIN
DOUT
Figure 6. Detailed Serial Interface Timing Diagram
Table 1. Command Word
B7 (MSB)B6B5B4B3B2B1B0 (LSB)Command B3Command B2Command B1Command B0Address B3Address B2Address B1Address B0
MAX1253/MAX1254
Stand-Alone, 10-Channel, 12-Bit System Monitors
with Internal Temperature Sensor and VDDMonitor
Manually Triggered Conversion
(Command Code = 0000)Before beginning a manual conversion, ensure the
scan mode bit in the setup register is zero, because a
logic 1 disables manual conversions. The address bits
in a Manually Triggered Conversion command select
the input channel for conversion (see Table 3). When
performing a differential conversion, use the even chan-
nel address (AIN0, AIN2, AIN4, AIN6); the command is
ignored if odd channel addresses (AIN1, AIN3, AIN5,
AIN7) are used for a differential conversion.
After issuing a Manually Triggered Conversion com-
mand, bring CShigh to begin the conversion. To obtain
a correct conversion result, CSmust remain high for a
period longer than the reference power-up time (if in
power-down mode) plus the conversion time for the
selected channel configured conversion type (voltage
or temperature). The conversion’s result can then be
read at DOUT by issuing a Read Current Data Register
for Selected Channel command, addressing the con-
verted channel. See Table 3 for channel addresses.
Table 2. Command Description
DATA BYTES AFTER
COMMAND WORDCOMMAND
WORDBYTES TO
DIN
BYTES
FROM DOUT
COMMAND DESCRIPTION0000####00Manually Trigged Conversion
0001xxxx03Read Alarm Register
0010####02Read Current Data Register for Selected Channel
0011####020Read Current Data Register for All Channels
0100####05Read Configuration Register for Selected Channel
0101xxxx05Read Global Configuration Registers
0110xxxxN/AN/AReserved
0111xxxx00Reset
1000####00Clear Alarm/Fault for Selected Channels
1001xxxx00Clear Alarm/Fault for All Channels
1010####20Write Current Data Register for Selected Channel
1011xxxx200Write Current Data Registers for All Channels
1100####50Write Configuration Registers for Selected Channel
1101xxxx50Write Global Configuration Registers
1110xxxxN/AN/AReserved
1111xxxxN/AN/AReserved
#### = Channel address code, see Table 3.
xxxx = These bits are ignored for this command.
Table 3. Channel Address
ADDRESS IN COMMANDINPUT0000Internal temperature
0001VDD
0010AIN0
0011AIN1
0100AIN2
0101AIN3
0110AIN4
0111AIN5
1000AIN6
1001AIN7
1010Reserved
1011Reserved
1100Reserved
1101Reserved
1110Reserved
1111Reserved
