Thermal
V = Voltage forward biased
f
V = Diode voltage while I is flowing
H
H
V = Diode voltage while I is flowing
L
L
I = Larger diode bias current
H
I = Smaller diode bias current
q = Charge of electron (1.6 x 10
L
–19
C)
n = Ideality factor (normally 1.0)
K = Boltzman’s constant (1.38 x 10 Joules/K)
T = Temperature (Kelvins)
–23
The ratio of I to I is usually selected to be 10:1. The above simplifies to the following:
H
L
–4
V – V = 1.986 × 10 × nT
H
L
Solving for T, the equation becomes:
V – V
H
L
__________
nT =
–4
1.986 × 10
MPC8572E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 4
Freescale Semiconductor
124