FCD4B14CU Atmel, FCD4B14CU Datasheet - Page 14

• Manufacturer Part Number: FCD4B14CU
• Manufacturer: Atmel

Specifications of FCD4B14CU

• Lead Free Status / Rohs Status: Compliant

Thermometer
14
FCD4B14
The dummy bytes DB3 and DB4 contains some internal and temperature information.
The even nibble nnnn in DB3 can be used to measure an increase (or decrease) of the
chip temperature, using the difference between two measures of the same physical
device. The following table gives values in Kelvin.
For code 0 and 15, the absolute value is a minimum (saturation).
When the image contrast becomes low because of a low temperature difference
between the finger and the sensor, it is recommended to use the temperature stabiliza-
tion circuitry to increase the temperature of two codes (i.e. from 8 to 10), to get at least
an increase >1.4 Kelvin of the sensor. This enables to recover enough contrast to get a
proper fingeprint for recognition purpose.
Decimal
nnnn
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Binary
nnnn
1111
1110
1101
1100
1011
1010
1001
1000
0111
0110
0101
0100
0011
0010
0001
0000
Temperature differential with code 8 in
Kelvin
< -16.8
-11.2
11.2
-1.4
-2.8
-4.2
-5.6
-8.4
8.4
5.6
4.2
2.8
1.4
-7
7
0
1962C–01/02