rt9232b Richtek Technology Corporation, rt9232b Datasheet - Page 4

• Manufacturer Part Number: rt9232b
• Description: Programmable Frequency Synchronous Buck Controller
• Manufacturer: Richtek Technology Corporation

RT9232B
To prevent OC form tripping in normal operation, R
OCSET
must be carefully chosen with :
1. Maximum R
at highest junction temperature
DS(ON)
2. MInimum I
from specification table
OCSET
Δ
3. I
> I
+
I
/2
L(MAX)
OUT(MAX)
L
Δ
I
= inductor ripple current
L
Under Voltage Protection
The under voltage protection function protects the converter
from an shorted output by detecting the voltage on FB pin
to monitor the output voltage. The UVP function cycles
soft-start function in a hiccup mode. When output voltage
lower than 75% of designated voltage, UVP function
initializes soft-start cycles. The soft-start function
discharges Css with 10μA current sink and disable PWM
operation. Then soft-start function recharges Css and
PWM operation resumes. The soft-start hiccup restarts
after SS voltage fully charges
to 4V if the output
short
event still remains. The converter is shutdown permanently
after 3 times hiccup and only restarting supply voltages
can enable the converter.
www.richtek.com
DS9232B-03 March 2007
4