PM6686TR STMicroelectronics, PM6686TR Datasheet - Page 31

• Manufacturer Part Number: PM6686TR
• Description: IC CTLR DUAL STEP DOWN VFQFPN32
• Manufacturer: STMicroelectronics

Specifications of PM6686TR

• Applications: Controller, Notebook Computers
• Voltage - Input: 5.5 ~ 28 V
• Number Of Outputs: 2
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• Output Voltage: 5.5 V
• Output Current: 100 mA
• Output Power: 4.3 mW
• Input Voltage: 5.5 V to 28 V
• Switching Frequency: 33 KHz
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-8522-2

PM6686
8.1.7
Figure 50. Internal supply diagram
Current sensing and current limit
The PM6686 implements a positive valley current limit to protect the application from an
overcurrent fault. Each section has an independent current limit setting. A new switching
cycle can't start until the inductor current is under the positive current limit threshold. Note
that the peak current flowing in the inductor can reach a value greater than the current limit
threshold by an amount equal to the inductor ripple current.
Figure 51. Current waveforms in current limit conditions
The inductor current is sensed during the off time T
across the low-side MOSFET using the R
PGND voltage). The voltage drop is compared to the threshold set with ILIM pin. If ILIM is
connected to a voltage higher than VCC-1V the limit is 100mV. A current of 5 µA is sourced
from the pin ILIM; if a resistor is connected between ILIM and ground the current limit is
given by the voltage at the ILIM pin. The device sets the PHASE voltage threshold at 1/10 of
the ILIM voltage.
Doc ID 15281 Rev 4
DS(on)
as a lossless sensing element (PHASE to
OFF
by measuring the voltage drop
Device description
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