PM6686 STMicroelectronics, PM6686 Datasheet - Page 9

• Manufacturer Part Number: PM6686
• Description: Dual Step-down Controller With Adjustable Voltages, Adjustable Ldo And Auxiliary Charge Pump Controller For Notebook
• Manufacturer: STMicroelectronics

PM6686
Table 2.
N°
20
21
22
23
24
25
26
27
28
29
30
31
32
PHASE2
HGATE2
LGATE2
REFIN2
BOOT2
CP_FB
PGND
OUT2
ILIM2
GND
SKIP
EN2
PG2
Pin
Pin descriptions (continued)
The CP_FB is used to monitor the optional external 14 V charge pump.
Connect a resistive voltage-divider from 14 V charge pump output to GND. If
CP_FB drops below the threshold voltage, the device performs a no audible
skip cycle. This charges the charge pump output (driven by LGATE1). Leave
CP_FB floating if the charge pump feedback is not needed.
Signal ground reference for internal logic circuitry and LDO. It must be
connected to the signal ground plan of the power supply and to the exposed
pad. The signal ground plan and the power ground plan must be connected
together in one point near the PGND pin.
Power ground. This pin must be connected to the power ground plan of the
power supply.
Low-side gate driver output for the section 2.
Bootstrap capacitor connection for the switching section 2. It supplies the
high-side gate driver.
Switch node connection and return path for the high-side driver for the
section 2. It is also used as positive and negative current sense input.
High-side gate driver output for section 2.
Enable input for the switching section 2.
– If EN2 < 0.8 V the switching section OUT2 is turned off and all faults are
– If EN2 > 2.4 V the switching section OUT2 is turned on.
If EN2 is connected to VREF2, the switching section OUT2 turns on after
the switching section OUT1 reaches regulation.
Power Good output signal for the section 2. This pin is an open drain output
and It is pulled down when the output of the switching section 2 is out of
+ 14% / - 10% of its nominal value.
Pulse skipping mode control input.
– If the pin is connected to VCC the PWM mode is enabled.
– If the pin is connected to GND, the pulse skip mode is enabled.
– If the pin is connected to VREF2 (or floating) the pulse skip mode is
Output voltage sense for the switching section 2.This pin must be directly
connected to the output voltage of the switching section. It provides also the
feedback for the switching section 2 when REFIN2 is tied to VREF3/VCC.
Positive current sense input for the switching section 2. It is possible to set a
threshold voltage that is compared with 1/10
during the off time.
Feedback input for the switching section 2:
– If this pin is connected to VCC, OUT2 operates at 3.3 V
– If this pin is connected to VREF3, OUT2 operates at 1.05 V
– If this pin is connected to an external reference from 0.7 V to 2.5 V, OUT2
cleared.
enabled but and the switching frequency is kept higher than 33 kHz (No-
audible pulse skip mode).
works in tracking with this reference. Bypass REFIN2 to GND with a 100
nF capacitor.
Doc ID 15281 Rev 4
Function
th
of the GND-PHASE2 drop
Pin settings
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