MAX1497 Maxim, MAX1497 Datasheet - Page 25

• Manufacturer Part Number: MAX1497
• Description: 3.5- and 4.5-Digit / Single-Chip ADCs with LED Drivers and C Interface
• Manufacturer: Maxim

Default values: B1E0h
The peak data register is a 16-bit read only register. Set
the PEAK bit to 1 to enable the PEAK function. This reg-
ister stores the peak value of the ADC conversion
result. First, the current ADC result is saved to the
PEAK register, then the new ADC conversion result is
compared to this value. If the new value is larger than
the value in the peak register, the MAX1497/MAX1499
save the new value to the peak register. If the new
value is less than the value in the peak register, the
value in the peak register remains unchanged. Set the
PEAK bit to zero to clear the value in the PEAK register.
The data is represented in two’s complement format.
For the MAX1499, the data is 16-bit and D15 is the MSB.
For the MAX1497, the data is 12-bit, D15 is the MSB, and
D4 is the LSB followed by 4 trailing sub-bits.
At power-on, the serial interface, logic LED drivers, dig-
ital filter, and modulator circuits reset. The registers
return to their default values. Allow time for the refer-
ence to settle before starting calibration.
The MAX1497/MAX1499 offer on-chip offset calibration.
The device offset calibrates during every conversion
Figure
DUMMY
ACTIVE
GAUGE
GAUGE
15. Strain-Gauge Application with the MAX1497/MAX1499
3.5- and 4.5-Digit, Single-Chip ADCs with LED
0.1µF
R
REF
0.1µF
R
R
0.1µF
0.1µF
0.1µF
______________________________________________________________________________________
4.7µF
REF+
REF-
AIN+
AIN-
AV
DD
ANALOG SUPPLY
MAX1497
MAX1499
Offset Calibration
FERRITE
GND
BEAD
Power-On Reset
DV
DD
0.1µF
SCLK
DIN
DOUT
CS
EOC
4.7µF
Drivers and µC Interface
when the OFFSET_CAL1 bit is zero in the control regis-
ter. Enhanced offset calibration is only needed in the
MAX1499 when the RANGE bit = 1. It is performed on
demand by setting the OFFSET_CAL2 bit to 1.
Enhanced offset calibration is a more accurate calibra-
tion method that is needed in the case of the ±200mV
range and 4.5-digit resolution. The MAX1499 performs
the enhanced calibration on demand by setting the
OFFSET_CAL2 bit to 1.
The MAX1497/MAX1499 feature independent power-
down control of the analog and digital LED drivers cir-
cuitry. Writing a 1 to the PD_DIG and PD_ANA bits in
the control word, powers down the analog and digital
circuitry, reducing the supply current to 268µA (typ).
PD_DIG powers down the digital filter, while PD_ANA
powers down the analog modulator and ADC input
buffers. Writing a zero to the ENABLE bit in the control
word, powers down the LED drivers.
The MAX1497/MAX1499 feature peak detection circuit-
ry. When activated (PEAK bit = 1), the devices display
only the highest voltage measured to the LED.
Figure
MAX6062
THERMOCOUPLE
16. Thermocouple Application with the MAX1497/MAX1499
JUNCTION
+5V
+2.048V
0.1µF
SENSOR
Enhanced Offset Calibration
TEMP
0.47µF
AIN+
AIN-
REF+
REF-
GND
Power-Down Modes
MAX1497
MAX1499
SPI
µC
Peak
25