L6731D Datasheet, PDF (7/23 Pages) STMicroelectronics – Adjustable step-down controller with synchronous rectification dedicated to DDR memory

L6731D
Pin connections and functions
Table 4.
Pin n.
8
9
10
11
12
13
14
15
16
Pin functions (continued)
Name
Function
A resistor connected from this pin to ground sets the valley- current-limit.
The valley current is sensed through the low-side MOSFET(s). The internal
current generator sources a current of 100 µA (I_OCL) from this pin to ground
through the external resistor (R_OCL). The over-current threshold is given by
the following equation:
OCL
I_VALLEY = ₂-^I--^O--_•--^C---_R-^L---_D-^•---_S-^R--_O---^O-_N---^C-_L---^LS--
OCH
PHASE
HGATE
BOOT
PGND
LGATE
V_CCDR
V_CC
Connecting a capacitor from this pin to GND helps in reducing the noise
injected from V_CC to the device, but can be a low impedance path for the
high-frequency noise related to the GND. Connect a capacitor only to a
"clean" GND.
A resistor connected from this pin and the high-side MOSFET(s) drain sets
the peak-current-limit. The peak current is sensed through the high-side
MOSFET(s). The internal 100 µA current generator (I_OCH) sinks a current
from the drain through the external resistor (R_OCH). The over-current
threshold is given by the following equation:
I_PEAK
=
I_{--O----C----H-----}•_----R_{-----O----C----H-}
R_DSONHS
This pin is connected to the source of the high-side MOSFET(s) and
provides the return path for the high-side driver. This pin monitors the drop
across both the upper and lower MOSFET(s) for the current limit together
with OCH and OCL.
This pin is connected to the high-side MOSFET(s) gate.
Through this pin is supplied the high-side driver. Connect a capacitor from
this pin to the PHASE pin and a diode from V_CCDR to this pin (cathode
versus BOOT).
This pin has to be connected closely to the low-side MOSFET(s) source in
order to reduce the noise injection into the device.
This pin is connected to the low-side MOSFET(s) gate.
5 V internally regulated voltage. It is used to supply the internal drivers.
Filter it to ground with at least 1 µF ceramic cap.
Supply voltage pin.
The operative supply voltage range is from 4.5 V to 14 V.
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