Datasheet

VCC Recommended Operating Range
VCC
ON
VCC
OFF
I
EN-START
I
EN-ON
VEN
ON
VEN
OFF
VCC, V
EN
(V)
t
I
EN
(μA)
(R
EN/TOFF
= 100 kΩ)
10
20
1
0
3
2
5
4
0
VCC
V
EN
t
EN/TOFF pin under
external control
~100 ns
~R
EN/TOFF
C
PIN
V10094
UCC24610
SLUSA87B –AUGUST 2010–REVISED SEPTEMBER 2010 www.ti.com
APPLICATION INFORMATION
Normal Operation
The UCC24610 GREEN Rectifier™ Synchronous-Rectifier (SR) controller powers up into UVLO Mode as VCC
increases from zero volts. Enable Current (I
EN
) from the EN/TOFF pin is inhibited until VCC exceeds the V
CC(on)
threshold, and remains active as long as VCC exceeds the V
CC(off)
threshold. The voltage on the EN/TOFF pin
determines whether the controller is Enabled or not. The controller operates in the normal Run Mode when the
Enable Voltage (VEN) exceeds the Enable threshold V
EN(on)
and remains enabled as long as V
EN
exceeds the
V
EN(off)
threshold.
After the controller is Enabled, V
EN
programs the minimum off time inversely proportional to the voltage (see T
OFF
section). The two-state Enable current allows a lower-value resistance for R
EN(off)
(necessary to program longer
off time) to still generate sufficient voltage to exceed V
EN(on)
at start-up. A simple resistor from EN/TOFF to GND
generates V
EN
based on the level of I
EN
current flowing through it. See Figure 17. Alternatively, V
EN
may be
driven by an external voltage source provided this voltage exceeds V
EN(on)
for at least 100 ns before settling to its
final programming level.
Figure 17. Behavior of I
EN
and V
EN
as VCC Varies (R
EN/TOFF
= 100 kΩ)
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