L9803 STMicroelectronics, L9803 Datasheet - Page 115

• Manufacturer Part Number: L9803
• Description: Super Smart Power Motor Driver With 8-bit Mcu, Ram, Eeprom, Adc, Wdg, Timers, Pwm And H-bridge Driver
• Manufacturer: STMicroelectronics

L9803
7.2
Power considerations
The average chip-junction temperature, T
following equation:
Where:
For most applications P
device is configured to drive Darlington bases or sink LED Loads.
An approximate relationship between P
Therefore:
Where:
Table 17.
(*) Maximum chip dissipation can directly be obtained from T
Symbol
–
–
–
–
–
–
P
D
T
θ
P
P
expressed in Watts. This is the Chip Internal Power
P
K is a constant for the particular part, which may be determined from equation (3)
by measuring P
of P
value of T
A
JA
D
INT
I/O
is the Ambient Temperature in °C,
Thermal Characteristics (VB=18V, T
is the sum of P
is the Package Junction-to-Ambient Thermal Resistance, in °C/W,
D
represents the Power Dissipation on Input and Output Pins; User Determined.
is the product of I
Dissipated Power
and T
A
.
J
may be obtained by solving equations (1) and (2) iteratively for any
I/O
Description
D
<<P
K = P
(at equilibrium) for a known T
INT
INT
and P
1
D
P
and VB, plus the power dissipated by the power bridge,
T
and may be neglected. P
x (T
D
J
= T
= K÷ (T
I/O
A
D
A
+ 273°C) + θ
,
J
and T
+ (P
, in degrees Celsius, may be calculated using the
J
D
+ 273°C) (2)
J
x θ
(if P
j
(max), θ
JA
J
I/O
JA
= 150°C, I
) (1)*
x P
is neglected) is given by:
JA
A.
and T
D
Using this value of K, the values
I/O
Value
2
3
may be significant if the
(3)
LOAD
A
parameters.
Electrical Characteristics
= 2A)
Unit
W
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