M1AFS600-PQ208 Datasheet, PDF (113/334 Pages) Microsemi Corporation – Fusion Family of Mixed Signal FPGAs

Fusion Family of Mixed Signal FPGAs
The diode’s voltage is measured at each current level and the temperature is calculated based on EQ 7.
V_TMSLO – V_TMSHI = nk--_q--^T--_ln^I-_I-^T-_T--^M-_M---^S-_S--^L-_H--^O-_I-_
EQ 7
where
I_TMSLO is the current when the Temperature Strobe is Low, typically 100 µA
I_TMSHI is the current when the Temperature Strobe is High, typically 10 µA
V_TMSLO is diode voltage while Temperature Strobe is Low
V_TMSHI is diode voltage while Temperature Strobe is High
n is the non-ideality factor of the diode-connected transistor. It is typically 1.004 for the Microsemi-
recommended transistor type 2N3904.
K = 1.3806 x 10^-23 J/K is the Boltzman constant
Q = 1.602 x 10^-19 C is the charge of a proton
When I_TMSLO / I_TMSHI = 10, the equation can be simplified as shown in EQ 8.
V = V_TMSLO – V_TMSHI = 1.986  10^–4nT
EQ 8
In the Fusion TMB, the ideality factor n for 2N3904 is 1.004 and V is amplified 12.5 times by an internal
amplifier; hence the voltage before entering the ADC is as given in EQ 9.
V_ADC = V  12.5 = 2.5 mV  K  T
EQ 9
This means the temperature to voltage relationship is 2.5 mV per degree Kelvin. The unique design of
Fusion has made the Temperature Monitor System simple for the user. When the 10-bit mode ADC is
used, each LSB represents 1 degree Kelvin, as shown in EQ 10. That is, e. 25°C is equal to 293°K and is
represented by decimal 293 counts from the ADC.
1K = 2.5 mV  ₂----_.-²⁵---¹-₆--⁰---_V-- = 1 LSB
EQ 10
If 8-bit mode is used for the ADC resolution, each LSB represents 4 degrees Kelvin; however, the
resolution remains as 1 degree Kelvin per LSB, even for 12-bit mode, due to the Temperature Monitor
design. An example of the temperature data format for 10-bit mode is shown in Table 2-38.
Table 2-38 • Temperature Data Format
Temperature
Temperature (K)
Digital Output
(ADC 10-bit mode)
–40°C
233
00 1110 1001
–20°C
253
00 1111 1101
0°C
273
01 0001 0001
1°C
274
01 0001 0010
10 °C
283
01 0001 1011
25°C
298
01 0010 1010
50 °C
323
01 0100 0011
85 °C
358
01 0110 0110
Revision 4
2- 97