MAX1298CEAE+ Maxim Integrated Products, MAX1298CEAE+ Datasheet - Page 16

• Manufacturer Part Number: MAX1298CEAE+
• Description: IC TEMP SENS W/ADC 16-SSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1298CEAE+

• Function: Temp Monitoring System (Sensor)
• Topology: ADC, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 85°C, External Sensor
• Output Type: MICROWIRE™, QSPI™, SPI™
• Output Alarm: No
• Output Fan: No
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP
• Full Temp Accuracy: +/- 1 C
• Digital Output - Bus Interface: Serial (3-Wire)
• Digital Output - Number Of Bits: 12 bit
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ence reflects the power requirement of an internal refer-
ence buffer amplifier that can accommodate external
loads. Temperature conversions at 100% duty cycle
increase supply currents to 440µA (400µA) through
additional amplification, buffer, and bias circuitry that is
otherwise inactive.
Place the MAX1298/MAX1299 in a low-current power-
down state between conversions to conserve power.
Select standby, standby-plus, or shutdown through bits
PM1 and PM0 of the initialization byte (Table 4).
The MAX1298/MAX1299 assume the shutdown power
mode when V
Standby mode turns off the MAX1298/MAX1299 ADC,
internal clock, and reference buffer amplifier. Special
circuitry for temperature conversions is also deactivat-
ed. Wake-up time is limited by the reference buffer
amplifier and the associated bypass capacitor (see
Internal Reference). When an external reference is
used, wake-up time is 0.1ms.
Standby-plus mode is similar to the standby mode, but
the internal reference output buffer remains active to
shorten the wake-up time to 0.1ms for internal refer-
ence mode. When using an external reference, stand-
by-plus mode is equivalent to standby mode.
Shutdown mode turns off all functions other than start-
up circuitry, thereby reducing typical supply current to
2µA. Data registers are cleared. Use this power mode
when interconversion times are no less than 5ms.
This mode of operation samples and converts the sup-
ply voltage, V
reference voltage must be larger than V
operation to work properly. From the result of a conver-
sion (CODE), CODE = 256 V
The MAX1298/MAX1299 perform temperature measure-
ments with internal or external diode-connected transis-
tors through a three-step process. First, the diode bias
current changes from 31.6µA to 10µA to produce a
temperature-dependent bias voltage difference, which
is amplified by a factor of 20 and converted to digital
format. Second, the bias current changes from 31.6µA
to 100µA, and the bias voltage difference is similarly
amplified by a factor of 20 and converted to digital for-
mat. Third, the intermediate results are subtracted to
12-Bit Serial-Output Temperature Sensors
with 5-Channel ADC
16
______________________________________________________________________________________
DD
DD
is first applied.
/4, which is internally generated. The
Temperature Measurements
DD
/ V
REF
Standby-Plus Mode
Monitoring V
.
Shutdown Mode
Standby Mode
DD
/8 for the
DD
achieve a digital output that is proportional to absolute
temperature in degrees Kelvin.
The reference voltage used in conjunction with tempera-
ture measurements is derived from the internal reference
source to ensure that 1LSB corresponds to 1/8 of a
degree. To convert to degrees Celsius, subtract 273.15
from the temperature inferred from the ADC output.
Temperature measurements require a conversion time
of 2.2ms.
The MAX1298/MAX1299 provide a shield output buffer
voltage at SHO that is approximately 0.6V (one diode
drop) above V
measurements with an external diode, use this voltage
to suppress error-producing leakage currents (see
Remote Diode Shielding). Figure 7 shows the SHO out-
put circuit.
Temperature accuracy depends on having a good-
quality, diode-connected small-signal transistor.
Accuracy has been experimentally verified for 2N3904
devices. CPUs and other ICs having on-board temper-
ature-sensing diodes can also be monitored if the
diode connections are floating.
Table 4. Power-Mode Selection
Figure 7. SHO Output Circuit
PM1
0
0
1
1
PM0
0
1
0
1
V
Applications Information
DD
DD
2
Shutdown
Standby-plus
Standby
Normal operation
/2. When performing temperature
Remote Diode Selection
Shield Output Buffer
5 µA
MODE
SHO