l6590a STMicroelectronics, l6590a Datasheet - Page 16

• Manufacturer Part Number: l6590a
• Description: Fully Integrated Power Supply
• Manufacturer: STMicroelectronics

L6590A
At turn-on, there are large current spikes due to the discharge of parasitic capacitances and, in case of Contin-
uos Conduction Mode operation, to secondary diode reverse recovery as well, which could falsely trigger the
OCP comparator. To increase noise immunity the output of the OCP comparator is blanked for a short time
(about 120 ns) just after the MOSFET is turned on, so that any disturbance within this time slot is rejected (Lead-
ing Edge Blanking).
Figure 31. OCP internal schematic
DRAIN
Max. Duty cycle
S
Driver
Clock
OSCILLATOR
R
Q
1
1/100
+
+
Rsense
PWM
OCP
-
-
LEB
Clock
0.5 V
GND
Thermal Shutdown
Overheating of the device due to an excessive power throughput or insufficient heatsinking is avoided by the
Thermal Shutdown function. A thermal sensor monitors the junction temperature close to the power MOSFET
and, when the temperature exceeds 150 °C (min.), sets an alarm signal that stops the operation of the device.
This is a not-latched funtion and the power MOSFET is re-enabled as the temperature falls about 40 °C.
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