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3/20
L6911C
PIN FUNCTION
Pin
Num.
Name Description
1 VSEN Connected to the output voltage is able to manage over-voltage conditions and the PGOOD
signal.
2 OCSET A resistor connected from this pin and the upper Mos Drain sets the current limit protection.
The internal 200
µ
A current
enerator sinks a current from the drain throu
h the external resistor.
The Over-Current threshold is due to the followin
equation:
3 SS/INH
The soft start time is pro
rammed connectin
an external capacitor from this pin and GND. The
internal current
enerator forces throu
h the capacitor 10
µ
A.
This pin can be used to disable the device forcin
a volta
e lower than 0.4V
4 - 8 VID0 - 4 Voltage Identification Code pins. These input are internally pulled-up and TTL compatible. They
are used to program the output voltage as specified in Table 1 and to set the overvoltage and
power good thresholds.
Connect to GND to program a ‘0’ while leave floating to program a ‘1’.
9 COMP This pin is connected to the error amplifier output and is used to compensate the voltage control
feedback loop.
10 FB This pin is connected to the error amplifier inverting input and is used to compensate the voltage
control feedback loop.
11 GND All the internal references are referred to this pin. Connect it to the PCB signal ground.
12 PGOOD This pin is an open collector output and is pulled low if the output voltage is not within the above
specified thresholds.
If not used may be left floating.
13 PHASE This pin is connected to the source of the upper mosfet and provides the return path for the high
side driver. This pin monitors the drop across the upper mosfet for the current limit
14 UGATE High side gate driver output.
15 BOOT Bootstrap capacitor pin. Through this pin is supplied the high side driver and the upper mosfet.
Connect through a capacitor to the PHASE pin and through a diode to Vcc (cathode vs. boot).
16 PGND Power ground pin. This pin has to be connected closely to the low side mosfet source in order to
reduce the noise injection into the device
17 LGATE This pin is the lower mosfet gate driver output
18 VCC Device supply voltage. The operative nominal supply voltage ranges from 5 to 12V.
DO NOT CONNECT V
IN
TO A VOLTAGE GREATER THAN V
CC
.
19 OVP Over voltage protection. If the output voltage reaches the 17% above the programmed voltage
this pin is driven high and can be used to drive an external SCR that crowbar the supply voltage.
If not used, it may be left floating.
20 RT Oscillator switching frequency pin. Connecting an external resistor from this pin to GND, the
external frequency is increased according to the equation:
Connecting a resistor from this pin to Vcc (12V), the switching frequency is reduced according to
the equation:
If the pin is not connected, the switching frequency is 200KHz.
The volta
e at this pin is fixed at 1.23V (t
p). Forcin
a 50
µ
A current into this pin, the built in
oscillator stops to switch.
I
P
I
OCSET
R
OCSET
⋅
R
DSon
----------------------------------------------=
f
S
200kHz
4.94 10
6
⋅
R
T
kΩ()
-------------------------+=
f
S
200kHz
4.306 10
7
⋅
R
T
kΩ()
-----------------------------–=
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