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If you don't used a heat sink then
the temperature of the transistor will be
roughly
Temperature = 62.5 * ( Vi - 5V) *I +
25
where 62.5 is the thermal
resistance from the junction to ambient
Vi is you Voltage input .
5V is your Voltage output.
25 is the ambiant temperature.
I is the current around (350 ma on the
ts7200 with no charge).
Then if the input is 9V the regulator
junction will be at 112 Celsius and the case at 108
Celsius.
Maximum junction is
150 Celsius.
You need a heat sink if you load is bigger or your voltage is
higher!,
I'm
using the Power Trends regulator from TI. They are direct replacement
for the LM7805 with the swithing technology.
I use
it with the TS7200 using 24VDC power supply in an environment that could
vary from 20C to 50C with no problem.
Daniel
On 09 Apr 2007 04:32:06 -0700, Taj Morton <m("gmail.com","tajmorton");">com>
wrote:
Hi All,
I've got a TS-7200 that I recently bought. It works fine, but
the vreg
I'm using gets _very_ hot while using it (e.g., it will burn
you). The
VReg is a ST Microelectronics LD1084D2M50R (5V, 5A) The product
is
listed at: http://tinyurl.com/37x7fk
The datasheet is at: http://www.st.com/stonline/books/pdf/docs/9035.pdf
I've
tried 2 vregs so far, (both the same model), and the same thing
happened
to both of them.
I don't have anything running off the board yet. I
had a CF card
plugged into it, but removing it changed nothing. Any
ideas?
Thanks!
- Taj
P=E X
I (Power = Volts X Current)
The TS7200 draws 450ma from a 5v supply. So
if the voltage into the regulator is 12v then the drop across the reg is 12v -
5v =7v. If the voltage across the reg is 7v, then the power being dissipated
is 7v X 450ma = 3.15 watts. That could be causing the regulator to be feeling
hot. What are you using for an input voltage?
Stephen
Queen
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