ST7263 STMICROELECTRONICS [STMicroelectronics], ST7263 Datasheet - Page 94

• Manufacturer Part Number: ST7263
• Description: LOW SPEED USB 8-BIT MCU FAMILY with up to 16K MEMORY, up to 512 BYTES RAM, 8-BIT ADC, WDG, TIMER, SCI & I2C
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ST7263
7.2 THERMAL CHARACTERISTICS
The average chip-junction temperature, T
grees Celsius, may be calculated using the follow-
ing equation:
Where:
– T
– J
– P
– P
– P
For most applications P
glected. P
figured to drive Darlington bases or sink LED Loads.
Table 25. Thermal Characteristics
(*): Maximum chip dissipation can directly be obtained from T
94/109
Resistance, in C/W,
Watts. This is the Chip Internal Power
and Output Pins; User Determined.
A
D
INT
I/O
A
Symbol
is the Ambient Temperature in C,
is the sum of P
is the Package Junction-to-Ambient Thermal
represents the Power Dissipation on Input
is the product of I
J
A
I/O
T
may be significant if the device is con-
J
= T
A
INT
+ (P
and P
DD and
I/O
D
x J
<P
PSDIP32
Package
I/O
INT
SO34
A
V
) (1)*
,
DD
and may be ne-
, expressed in
J
, in de-
An approximate relationship between P
(if P
Therefore:
Where:
– K is a constant for the particular part, which may
be determined from equation (3) by measuring
P
ue of K, the values of P
by solving equations (1) and (2) iteratively for any
value of T
D
I/O
(at equilibrium) for a known T
K = P
is neglected) is given by:
j
Typical Value
(max),
D
A
P
.
x (T
70
50
D
= K (T
JA
A
+ 273°C) + J
and T
J
D
A
+ 273°C) (2)
and T
parameters.
J
A
may be obtained
A.
x P
Using this val-
D
2
D
°C/W
Unit
and T
(3)
J