Datasheet

TPS2590
CT
OUT
IN
FLT
ILIM
RTRY
IFLT
GND
38.3kΩ
C
LOAD
Optional:
To System
Monitor
12V Bus
16
EN
6
7 8
9
15
0.39uF
47.5kΩ
4.6V
FET
100kΩ
ON
2
IN
LOAD MIN
LIM _ MIN
V
R R
4 P
> =
´
2
MIN LIM _ MIN IN
4 R P V´ ´ >
TPS2590
www.ti.com SLUS960F –JULY 2009–REVISED MAY 2013
(10)
(11)
Enable Pin Considerations
For the case when EN is simply connected to GND, TPS2590 will start ramping the voltage on OUT as IN rises
above UVLO (~2.85V typical). If IN does not ramp monotonically, the TPS2590 may momentarily turn off then on
during startup if IN falls below ~2.70V. To avoid this problem, EN assertion can be delayed until IN is sufficiently
above UVLO. A simple approach is shown in Figure 16. The 100kΩ pullup resistor will de-assert EN when IN is
above ~1.75V maximum which is well below the minimum UVLO of ~2.6V. The Zener diode ensures that EN
remains below 5V. User control to enable the TPS2590 can be applied at the ON node to turn on the FET once
IN has risen sufficiently above UVLO.
Figure 16. EN Delay Circuit
Fault Timer
The fault timer is active when the TPS2590 is in SOA protect mode or the current is above I
FAULT
. Figure 17
illustrates operation during non-faulted start up (C
LOAD
=470 µF and I
OUT
= 1A in a 12V system). C
CT
charges at
~35µA until TPS2590 exits SOA protect mode, discharges quickly (~40µA) to ~0.16V, and then decays slowly
(~1.4µA) towards zero.
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