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 2
IN IN
LOAD MIN
LIM _ MIN
V V
R R
4 P 12
> = =
´
2
MIN LIM _ MIN IN
4 R P V´ ´ >
TPS2590
www.ti.com SLUS960G –JULY 2009–REVISED JANUARY 2014
(10)
(11)
Enable Pin Considerations
For the case when EN is simply connected to GND, TPS2590 device begins ramping the voltage on OUT as IN
rises above UVLO (~2.85V typical). If IN does not ramp monotonically, the TPS2590 device can momentarily turn
off then on during startup if IN falls below approximately 2.7 V. To avoid this problem, EN assertion can be
delayed until IN is sufficiently above UVLO. A simple approach is shown in Figure 16. The 100-kΩ pullup resistor
de-asserts EN when IN is above approximately 1.75 V maximum which is well below the minimum UVLO of
approximately 2.6 V. The Zener diode ensures that EN remains below 5 V. User control to enable the TPS2590
device 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 device 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
= 1 A in a 12-V system). C
CT
charges at approximately 35 µA until the TPS2590 device exits SOA-protect mode, discharges quickly
(approximately 40 µA) to approximately 0.16 V, and then decays slowly (approximately 1.4 µA) towards zero.
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