PM6685 STMicroelectronics, PM6685 Datasheet - Page 44

• Manufacturer Part Number: PM6685
• Description: IC CTLR DUAL SYNC STDN 5X5VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6685

• Applications: Controller, Notebook Power System
• Voltage - Input: 6 ~ 28 V
• Number Of Outputs: 2
• Voltage - Output: -3.3V, 5V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• Output Voltage: 5 V, 3.3 V
• Output Current: 0.1 A
• Input Voltage: 5.5 V to 28 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 10 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Design example
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Figure 41. Current paths, ground connection and driver traces layout
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As general rule, make the high side and low side drivers traces wide and short.
The high side driver is powered by the bootstrap circuit. It’s very important to place
capacitor CBOOT and diode DBOOT as near as possible to the HGATE pin (for
example on the layer opposite to the device). Route HGATE and PHASE traces as near
as possible in order to minimize the area between them.
The Low side gate driver is powered by the 5V linear regulator output. Placing PGND
and LGATE pins near the low side MOSFETs reduces the length of the traces and the
crosstalk noise between the two sections.
The linear regulator outputs are referred to SGND as long as the reference voltage
Vref. Place their output filtering capacitors as near as possible to the device.
Place input filtering capacitors near VCC and VIN pins.
It would be better if the feedback networks connected to COMP and OUT pins are
“referred” to SGND in the same point as reference voltage Vref. To avoid capacitive
coupling place these traces as far as possible from the gate drivers and phase
(switching) paths.
Place the current sense traces on the bottom side. Use a dedicated connection
between the switching node and the current limit resistor RCSENSE.
Doc ID 11674 Rev 8
PM6685