ame5142 AME, Inc., ame5142 Datasheet - Page 9

• Manufacturer Part Number: ame5142
• Description: White Led Boost Converter In Tiny Package
• Manufacturer: AME, Inc.

Thermal Considerations
Shutdown Pin Operation
directly to V
recommended). The EN pin must not be left unterminated.
Rev. A.04
AME5142
n Application Hints
power dissipation within the AME5142 switch. The switch power dissipation from ON-state conduction is calculated by:
dissipation.
Calculating Load Current
The device is turned off by pulling the shutdown pin low. If this function is not going to be used, the pin should be tied
At higher duty cycles, the increased ON time of the FET means the maximum output current will be determined by
P
There will be some switching losses as well, so some derating needs to be applied when calculating IC power
The load current is related to the average inductor current by the relation:
I
Where “ D” is the duty cycle of the application. The switch current can be found by:
I
Inductor ripple current is dependent on inductance, duty cycle, input voltage and frequency:
I
Combining all terms, we can develop an expression which allows the maximum available load current to be calculated:
LOAD
SW
RIPPLE
I
(SW)
LOAD
= I
= I
= D x I
= D x (V
IND
= ( 1-D ) x ( I
IND
(AVG) + 1 /2 (I
(AVG) x (1 - D)
IN
. If the SHDN function will be needed, a pull-up resistor must be used to V
IND(AVE)2
AME, Inc.
IN
-V
SW
x R
) / (f x L)
SW
DS
RIPPLE
(max) -
(ON)
)
D ( V
2fL
IN
-V
SW
)
)
White LED Boost Converter
In Tiny Package
IN
(approximately 50k-100k
9