Datasheet

3.5
3
2.5
2
1.5
1
0.5
0
10 60 110 160 210 260 310 360 410 460 510 560 610 660 700
Current-Limit Programming Resistor of ILIM_SET - kW
OUT Short Circuit Current Limit - A
V = 5 V
IN
I
OS_TYP
OS_ TYP
ILIM
51228
I
R
=
TPS2511
www.ti.com SLUSB18 –JUNE 2012
Current-Limit Threshold
The TPS2511 has a current-limiting threshold that is externally programmed with a resistor. Equation 1 and
Figure 30 help determine the typical current-limit threshold:
where
• I
OS_TYP
is in mA and R
ILIM
is in kΩ
• I
OS_TYP
has a better accuracy if R
ILIM
is less than 210 kΩ (1)
Figure 30. Typical Current Limit vs Programming Resistor
Current Sensing Report (CS)
The CS open-drain output is asserted immediately when the OUT pin current is more than about half of the
current limit set by a resistor on ILIM_SET pin. Built-in hysteresis improves the ability to resist current noise on
the OUT pin. The CS output is active low. The recommended operating sink current is less than 2 mA and
maximum sink current is 10 mA.
Undervoltage Lockout (UVLO) and Enable (EN)
The undervoltage lockout (UVLO) circuit disables the power switch and other functional circuits until the input
voltage reaches the UVLO turn-on threshold. Built-in hysteresis prevents unwanted oscillations on the output due
to input voltage drop from large current surges.
The logic input of the EN pin disables all of the internal circuitry while maintaining the power switch off. A logic-
high input on the EN pin enables the driver, control circuits, and power switch. The EN input voltage is
compatible with both TTL and CMOS logic levels.
Soft-Start, Reverse Blocking and Discharge Output
The power MOSFET driver incorporates circuitry that controls the rise and fall times of the output voltage to limit
large current and voltage surges on the input supply, and provides built-in soft-start functionality. The TPS2511
power switch blocks current from the OUT pin to the IN pin when turned off by the UVLO or disabled. The
TPS2511 includes an output discharge function. A 500-Ω (typ.) discharge resistor dissipates stored charge and
leakage current on the OUT pin when the device is in UVLO or disabled. However as this circuit is biased from
the IN pin, the output discharge is not active when the input approaches 0 V.
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