Hi,
I wanted to know if the TPS54233-Q1 is an appropriate choice in the following circuit to overcome a problem with a 9Vdc power supply which has a current limit of 1A:
(The datasheet for the buck converter is here: http://www.ti.com/lit/ds/symlink/tps54233-q1.pdf )
Don't know if this description is helpful or not, but just in case: the circuit in question is a very simple transistor gain tester which uses a (current) shunt resistor to display a voltage on a simple ADC.
Most of the transistors don't get anywhere near to 1A, but a Darlington with a gain of about 1,800 outputs 1.8V, i.e. 1.8A - if I've understood what's happening, then this causes the circuit to droop within milliseconds, and I need/want to read the "hFE" on the display for about half a second max. I'm using a 7805 to get 5Vdc voltage from a 9V input with 10uA, 100uA and 1mA base current sources, and 10Ω, 1Ω and 100mΩ shunts (on a 200mV scale, and it's unlikely but I may change that to a 2V scale).
The objective is to either power the circuit from a 9Vdc/1A supply, or hopefully from a typical 9V battery (as are found in DMMs).
I have read a little about buck (and boost) converters, but am not sure I have understood what I need to:
a) Can I use a buck converter, such as - and specifically - the TPS54233-Q1, to boost the available max.1A current the DC adapter can provide up to approx. 2A for high gain devices for half a second when needed?
b) Does the TPS54233 output a constant current or only what is demanded by the circuit at any given moment? - The intention is to measure/guage the approximate gain of BJTs ranging from 3904s up to a TIP120/125.
Thanks.