5

UCC3830-4/-5/-6

The curves shown in Figures 1 and 2 depict the typical

high gain-bandwidth products for the UCC3830-x Voltage

Amplifier, Current Amplifier and Current Sense Ampli-

fiers. These high gain-bandwidth devices help achieve

an excellent transient response to load and line changes.

TYPICAL PERFORMANCE CURVES

Figure 1. Open loop gain for UCC3830 voltage and

current amplifier.

Figure 2. Current sense amplifier gain vs frequency.

Short Circuit Current Limit

ISC =

1.28V

RSENSE • GCSA

15.

17A using the UCC3830-5

RSENSE =

1.28V

17A • 15

= 0.005

Ω.

A lower resistance value may be needed if the AC ripple

current in the inductor is more than 20% of the load cur-

rent.

APPLICATION INFORMATION

Figure 3. Short circuit foldback reduces stress on

circuit components by reducing short circuit current.

VSENSE (Output Voltage Sensing Input): This pin is

connected to the system output voltage through a low

pass filter. When the voltage on VSENSE rises above or

falls below the COMMAND voltage by 8.5%, the

PWRGOOD

output

is

driven

low

to

reset

the

microprocessor. When the voltage on VSENSE rises

above the COMMAND voltage by 17.5%, the OVP

comparator pulls the current amplifier output voltage

below the oscillator valley voltage to force zero duty

cycle at the GATE output. This pin is also used by the

foldback current limiting circuitry.

PIN DESCRIPTIONS (cont.)