LM5060Q1 National Semiconductor Corporation, LM5060Q1 Datasheet - Page 14

• Manufacturer Part Number: LM5060Q1
• Description: High-side Protection Controller With Low Quiescent Current
• Manufacturer: National Semiconductor Corporation

www.national.com
V
The LM5060 includes a V
voltage difference between the SENSE pin and the OUT pin.
If the voltage at the OUT pin falls lower than the voltage at the
SENSE pin, the V
nPGD pin to a high impedance state. It will also initiate charg-
ing of the capacitor on the TIMER pin with a 6 µA (typical)
current source if V
current source if V
TIMER pin reaches the typical 2V fault threshold, the gate of
the N-Channel MOSFET is pulled low with a 80 mA (typical)
sink current.
start-up. The nPGD pin never switches low because the V
fault comparator detects excessive V
the entire sequence.
OVER-CURRENT FAULT
The V
Current shutdown function. The V
itors the voltage difference between the SENSE pin and the
OUT pin. This is, essentially, the same voltage that is across
the N-Channel MOSFET R
that is set by the series resistor on the SENSE pin. The value
ENABLE
The LM5060 Enable pin (EN) allows for remote On/Off con-
trol. The Enable pin on/off thresholds are CMOS compatible.
The external N-Channel MOSFET can be remotely switched
Off by forcing the EN pin below the lower input threshold,
EN
remotely switched On by forcing the EN pin above the upper
input threshold, EN
levels of the Enable pin.
When the EN pin is less than 0.5V (typical) the LM5060 enters
a low current (disabled) state. The current consumption of the
VIN pin in this condition is 9 µA (typical).
DS
THL
FAULT CONDITION
DS
(800 mV). The external N-Channel MOSFET can be
Fault Comparator can be used to implement an Over-
Figure 4
DS
GS
GS
THH
Fault Comparator will trip and switch the
is less than than 5V, or a 11 µA (typical)
is higher than 5V. If the voltage on the
illustrates a V
(2.00V).
DS
Fault Comparator that senses the
DS(ON)
Figure 5
FIGURE 4. Voltages During Startup with V
DS
less the threshold voltage
DS
Fault Comparator mon-
DS
fault condition during
shows the threshold
voltage throughout
DS
14
of capacitor on the TIMER pin, the capacitor charge current
(I
old (V
FET will be allowed to conduct excessive current before the
MOSFET is turned-off. When this delay time expires, the gate
is discharged at a 80 mA rate.
The LM5060 is intended for applications where precise cur-
rent sensing is not required, but some level of fault protection
is needed. Examples are applications where inductance or
impedance in the power path limits the current rise in a short
circuit condition.
The Safe Operating Area (SOA) of the external N-Channel
MOSFET should be carefully considered to ensure the peak
drain-to-source current and the duration of the fault delay time
is within the SOA rating of the MOSFET. Also note that the
R
fect the accuracy of the Over-Current detection.
RESTART AFTER OVER-CURRENT FAULT EVENT
When a V
voltage has reached 2V, the LM5060 latches off the external
MOSFET. In order to initiate a restart, either the EN pin, the
VINpin, or the UVLO pin must be toggled low and then high.
TIMERH
DS(ON)
TMRH
FIGURE 5. Enable Function Threshold Levels
, 11 uA typical), along with the TIMER pin fault thresh-
variations of the external N-Channel MOSFET will af-
DS
DS
) will determine the how long the N-Channel MOS-
Fault Condition
fault condition has occurred and the TIMER pin
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