mlx90313 ETC-unknow, mlx90313 Datasheet - Page 9

• Manufacturer Part Number: mlx90313
• Description: Programmable Ir Sensor Interface
• Manufacturer: ETC-unknow

Analog Section
Supply regulator and Power-ON Reset
The on-chip supply regulator and can be powered by an automotive ignition supply line (7V-80V). The
chip can withstand SAE standard ignition transients. The resulting voltage of the regulator is available on
VDD (5V 300mV). The VDD pin can source up to 20mA to external circuitry. The chip can also be
supplied directly with a 5V regulated supply on pin VDD.
The power-on reset (POR) circuitry is completely internal. The chip is fully operational 16ms from the time
the supply crosses 1.3V. The POR circuit will issue another POR if the supply voltage goes below 1.3V.
Band-gap, DAC and ADC references
The on-chip trimmable, curvature compensated band-gap circuitry provides a stable reference level (less
than 10ppm per °C) for several derived reference potentials used for normal operation in MLX90313.
The analog ground at the AGND pin is directly derived from this band-gap voltage. The output voltages
from both amplifier chains are relative to this potential. The AGND reference can be trimmed internally to
(2.5V 20mV). The regulator at AGND pin can be switched off to minimize the current consumption. The
pin can be also used as external input for the internal 12-bit ADC.
The reference voltages for ADC and DAC are also derived from the band-gap. The DAC reference is
available at pin VREFP. The MLX90313 DAC reference voltage can be programmed on chip to one of the
following values: 2, 2.5, 3, 3.5, 4 and 4.5 V. Depending on the customer application Melexis can program
the linearised analog outputs for object and ambient temperatures providing absolute voltage/temperature
dependence. The internal regulator for the DAC reference voltage can be switched off to minimize the
consumption (if linearised analog output is not in use) or to use externally supplied reference for DAC
reference in range 2 to 5V
The ADC reference is 2.5V typically. The chip can be also programmed to use external ADC reference
connected to pin AGND. The current reference bias voltage (present at CREF pin) is also derived from
the on-chip band-gap reference.
IR-amplifier chain
MLX90313 is available with gain settings for the IR-amplifier chain ranging from 55 to 5500. The gain can
be selected by setting the appropriate bits of the ‘Irgain1’-register (EEPROM address 00h) according to
the table below. Any gain between the abovementioned limits can be obtained within an accuracy of
sensors, with output resistance of 50k
noise of the sensor and will rise up to 45nVrms/ Hz. The offset for the chopper stabilized amplifier path
can be largely calibrated out and amounts to maximum 4 V.
The common mode input range of the amplifier is –100mV to VDD - 3V. The output range of the amplifier
is 0V to VDD-0.2V. The output of the amplifier is referred to the potential on AGND.
IR chain gain settings
stage
contr.
bits
setting
MLX90313 Programmable IR sensor Interface
3901090313
G
6.5%. The amplifier input-referred white noise level is below 23nVrms/ Hz. In the application with IR-
IR
G
GCI0
0
1
G
pr
pr
G
b
10
20*
G
pa
GCI3
0
1
1
1
1
G
G
b
l
GCI2
X
0
0
1
1
GCI1
X
0
1
0
1
typical, the total system noise will however depend mainly on the
5
10
15
20
25
Page 9
GCI4
0
1
G
Programmable IR Sensor Interface
pa
1
5
GCI7
0
0
0
0
1
1
1
1
G
l
GCI6
0
0
1
1
0
0
1
1
MLX90313
GCI5
0
1
0
1
0
1
0
1
Rev 1.0 21-July-2001
1.067
1.143
1.231
1.333
1.455
1.600
1.778
2.000