MAX1298CEAE+ Maxim Integrated Products, MAX1298CEAE+ Datasheet - Page 12

• 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

Figure 2 shows a simplified model of the converter
input structure. Once initiated, a voltage conversion
requires 64 f
master clock. Each conversion is preceded by 13 f
periods of warm-up time, performed in twelve 4 f
period cycles, and followed by 3 f
the output register. SSTRB falls at the beginning of a
conversion and rises at the end of a conversion.
Inputs IN+ and IN- charge capacitors C
C
that occurs during the first f
version cycle. In the second f
switches open so that charge is retained on C
and C
between IN+ and IN-. This charge is transferred to the
ADC during the third and fourth f
The reference sampling process begins in the second
conversion cycle and continues until the conversion is
complete. Sampling occurs during the second and
fourth f
reference voltage. The reference sampling requirement
12-Bit Serial-Output Temperature Sensors
with 5-Channel ADC
Figure 2. Converter Input Structure
12
HOLDN
______________________________________________________________________________________
HOLDN
CLK
, respectively, during the acquisition interval
periods to yield an effective doubling of the
REF
IN+
IN-
CLK
as a sample of the differential voltage
periods, where f
TRACK AND HOLD
CLK
R IN
40k
R IN
40k
30k
Converter Operation
R R
CLK
period of the first con-
CLK
CLK
CLK
periods.
period, the T/H
T/H
T/H
periods to load
is the internal
HOLDP
HOLDP
C HOLDP
4pF
C HOLDN
4pF
C REF
4pF
and
CLK
CLK
is signal dependent and may or may not occur in every
subsequent conversion cycle.
Temperature conversion is essentially nothing more than
subtracting the results of two sequential voltage conver-
sions. The only difference is that output registers are not
loaded at the end of the first conversion. Thus, tempera-
ture conversions require 2 x 64 - 3 = 125 f
Figures 3a and 3b show timing diagrams for voltage
and temperature conversions, respectively.
The T/H stage for the MAX1298/MAX1299 is a simple
switched-capacitor sampling operation. The time
required for the T/H stage to acquire an input signal is
a function of how fast its input capacitance is charged.
If the signal source impedance is high, the acquisition
time lengthens and more time must be allowed
between conversions. The acquisition time (t
maximum time the device takes to acquire the signal.
Calculate this with the following equation:
where R
R
IN
is the T/H input impedance (40kΩ), and C
s
is the source impedance of the input signal,
GAIN
OF 2
t
ACQ
TIMING/CONTROL
DIFFERENTIAL
= 7 (R
LOGIC
FULLY
A/D
s
+ R
IN
) C
OUTPUT
IN
Track/Hold
CLK
ACQ
IN
periods.
) is the
is the