L6722TR STMicroelectronics, L6722TR Datasheet - Page 21

• Manufacturer Part Number: L6722TR
• Description: IC BUCK ADJ 2A TRPL 36VFQFPN
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of L6722TR

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 3
• Voltage - Output: Adj to 0.8V
• Current - Output: 2A
• Frequency - Switching: 100kHz
• Voltage - Input: 12V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 36-VFQFN, 36-VFQFPN
• Power - Output: 3.5W
• Operating Temperature Range: - 40 C to + 125 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-5904-2

L6722
8
8.1
Soft start
L6722 implements a soft-start to smoothly charge the output filter avoiding high in-rush currents
to be required to the input power supply. The device increases the reference from zero up to
the programmed value in 2048 clock periods and the output voltage increases accordingly with
closed loop regulation. At the end of the digital Soft-Start, PGOOD signal is set free.
Protections are active during this phase; Under Voltage is enabled when the reference voltage
reaches 0.6V while Over Voltage is always enabled with a threshold dependent on the selected
Operative Mode
The device implements Soft-Start only when all the power supplies are above their own turn-on
thresholds and the INH pin is set free.
Low-side-less startup for pre-bias output
To manage pre-biased output start-up and in order to avoid any kind of negative undershoot
and dangerous return from the load, L6722 performs a special sequence in enabling LS driver
to switch: during the soft-start phase, the LS driver results disabled (LS=OFF) until the HS
starts to switch. This avoid the dangerous negative spike on the output voltage that can happen
if starting over a pre-biased output (See
This particular feature of the device masks the LS turn-on only from the control-loop point of
view: protections are still allowed to turn-on the ls mosfet in case of over-voltage if needed.
Figure 11. low-side-less startup
Figure
11).
8 Soft start
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