3BABY
Member level 5
- Joined
- Jan 14, 2011
- Messages
- 91
- Helped
- 0
- Reputation
- 0
- Reaction score
- 0
- Trophy points
- 1,286
- Location
- New Zealand
- Activity points
- 2,252
R5 and R6 are there to equalize or ballance currents flowing out from above two regulators. Power rating for those two resistors and R2 is 5A*5A*0.1=2.5W~3W. R1 must be 10A*10A*0.05=5W which you can make paralleling two 0.1 ohm/3W resistors. OP177 is wrong choice because it's vorking positive input voltage is less than positive supply voltage (Vsup=+-15V, IVR=+-13V...+-14V). It will not work. Search for input rail to rail OPA.
Max allowed current through 0.1ohm resistor is 5A and through 0.05ohm is two times bigger. Power dissipated on resistor is calculated by using Ohms Law. Both demo circuits has no overcurrent protection or current limiting and in case of short circuit on the output components will be destroyed.
I am not shure that LM741 can replace LM308 regarding circuit stability.
As I can see you are a begginer and it would be better to find schematics of working power supply instead to use demo circuits from datasheets.
A unique feature of the LM138 family is time-dependent
current limiting. The current limit circuitry allows peak currents
of up to 12A to be drawn from the regulator for short
periods of time. This allows the LM138 to be used with heavy
transient loads and speeds start-up under full-load conditions.
Under sustained loading conditions, the current limit
decreases to a safe value protecting the regulator. Also
included on the chip are thermal overload protection and
safe area protection for the power transistor. Overload protection
remains functional even if the adjustment pin is accidentally
disconnected.
resistors values of 0.1 ohm each. this would give me a power dissipation of 2.5W when 5A is being drawn from each regulator
Resistors are characterized by their resistance and max power...but im still confused why we are applying an equation of P = I^2 * R for the resistor minimum safe power rating, and not P= V*I ?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?