EVALA5973AD STMicroelectronics, EVALA5973AD Datasheet - Page 9

• Manufacturer Part Number: EVALA5973AD
• Description: Power Management Modules & Development Tools EVAL BOARD A5973AD Auto Grade
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of EVALA5973AD

• Input Voltage: 4.4 V to 36 V
• Output Voltage: 1.235 V to 35 V
• Board Size: 23 mm x 20 mm
• Product: Power Management Modules
• Supply Current: 2.5 A
• Dimensions: 23 mm x 20 mm
• For Use With/related Products: AN1518
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AN1518
3.7
However, there is a limit introduced by the recovery time of the recirculation diode.
In fact, when the current of the power element is equal to the inductor current, the diode
turns OFF and the drain of the power is able to go high. But during its recovery time, the
diode can be considered a high value capacitor and this produces a very high peak current,
responsible for numerous problems:
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The fall time of the current during turn OFF is also critical, as it produces voltage spikes (due
to the parasitics elements of the board) that increase the voltage drop across the PDMOS.
In order to minimize these problems, a new driving circuit topology has been used and the
block diagram is shown in
turn the power switch ON and OFF, based on the PDMOS and the gate clamp status.
This circuitry allows the power switch to be turned OFF and ON quickly and addresses the
freewheeling diode recovery time problem. The gate clamp is necessary to ensure that V
of the internal switch does not go higher than V
against any cross conduction between the supply line and ground.
Figure 8.
Inhibit function
The inhibit feature is used to put the device in standby mode. With the INH pin higher than
2.2 V the device is disabled and the power consumption is reduced to less than 100 µA.
With the INH pin lower than 0.8 V, the device is enabled. If the INH pin is left floating, an
internal pull up ensures that the voltage at the pin reaches the inhibit threshold and the
device is disabled. The pin is also V
Spikes on the device supply voltage that cause oscillations (and thus noise) due to the
board parasitics.
Turn ON overcurrent leads to a decrease in the efficiency and system reliability.
Major EMI problems.
Shorter freewheeling diode life.
Driving circuitry
Figure 8
. The basic idea is to change the current levels used to
cc
compatible.
GS
max. The ON/OFF Control block protects
Functional description
9/30
GS