L5988D データシートの表示（PDF） - STMicroelectronics
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L5988D Datasheet PDF : 10 Pages
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Pin connections and functions
2 Pin connections and functions
L5988
Figure 1. Pin connection ( Top view)
VOUT
1
VCC
2
VCC
3
VCC
4
SS/INH
5
COMP
6
ILIM-ADJ
7
FB
8
16
VOUT
15
GND
14
GND
13
GND
12
VREF
11
OUS
10
FSW
9
SYNCH
Table 1. Pin functions
No Pin Name
Description
2,3,4
VCC Unregulated DC input voltage.
1,16
VOUT Regulator output.
13,14,15 GND Ground.
It is a Master-Slave pin. Two or more devices can be synchronized by simply connecting the
9
SYNCH SYNCH pins together. The device operating with the highest FSW will be the Master. The
Slave devices will operate with 180° phase shift from the Master.
Connecting an external resistor from this pin to GND, the external frequency can be increased
up to 1 MHz. Connecting an external resistor from this pin to VREF (1.8V), the switching
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FSW frequency can be decreased down to 200 KHz. If the pin is left open, the default switching
frequency is 400 KHz. The pin voltage is 1.2V. In OVP the pin is pulled up to 3.3V (only in
latched mode).
This pin is connected to the error amplifier inverting input. Connect it to the output resistor
8
FB divider (if used) or directly to Vout. This pin is also used to sense the output voltage in order to
manage the over voltage condition.
6
COMP
This pin is connected to the error amplifier output and is used to compensate the voltage
control feedback loop.
The soft-start time is programmed connecting an external capacitor from this pin and GND.
5
SS/INH The internal current generator forces a current of 22 µA through the capacitor. When the
voltage at this pin is lower than 0.65V the device is disabled.
12
VREF
Internally regulated voltage of 1.8V. It is used to provide a voltage reference for the
multifunction pin. Filter this pin to ground with at least 1µF ceramic cap.
Connecting a resistor between this pin and GND it is possible to increase the over current
7 ILIM-ADJ protection threshold. Connecting a resistor between this pin and VREF it is possible to
decrease the over current protection threshold.
Multifunction pin. Depending on the voltage level at the input, with this pin it is possible:
– to enable-disable the sink mode current capability after soft-start;
– to enable-disable the latch mode for the OVP;
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S/O/U
– to set the UVLO threshold for the 3.3V BUS and 12V BUS. (2.4V and 8V respectively);
The device continuously checks the analog value present at this pin and sets the
function according with the measured voltage.
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