L6932 Просмотр технического описания (PDF) - STMicroelectronics
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L6932 Datasheet PDF : 11 Pages
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L6932
Multilayer ceramic caps have the lowest ESR and can be required for particular applications. Nevertheless in
several applications they are ok, the loop stability issue has to be considered (see loop stability section).
Below a list of some suggested capacitor manufacturers.
Manufacturer
Type
Cap Value (µF)
Rated Voltage (V)
PANASONIC
CERAMIC
1 to 47
4 to 16
TAYO YUDEN
CERAMIC
1 to 47
4 to 16
TDK
CERAMIC
1 to 47
4 to 16
TOKIN
SANYO
PANASONIC
KEMET
CERAMIC
POSCAP
SP
TANTALUM
1 to 47
1 to 47
1 to 47
1 to 47
4 to 16
4 to 16
4 to 16
4 to 16
Loop Stability
The stability of the loop is affected by the zero introduced by the output capacitor.
The time constant of the zero is given by:
T = ESR ⋅ COUT
FZERO
=
---------------------1-----------------------
2π ⋅ ESR ⋅ COUT
This zero helps to increase the phase margin of the loop until the time constant is higher than some hundreds
of nsec, depending also on the output voltage and current.
So, using very low ESR ceramic capacitors could produce oscillations at the output, in particular when regulating
high output voltages (adjustable version).
To solve this issue is sufficient to add a small capacitor (e.g. 1nF to 10nF) in parallel to the high side resistor of
the external divider, as shown in figure 9.
Figure 9. Compensation Network
VIN=2V TO 14V
C1
IN
2
OUT
4
L6932D1.2
EN
1
5
67
GND
R1
ADJ
3
8
R2
VOUT=1.2V TO 5V UP to 2A
C3
C2
Thermal Considerations
Since the device is housed in a small SO(4+2+2) package the thermal issue can be the bottleneck of many ap-
plications. The power dissipated by the device is given by:
PDISS = (VIN - VOUT) · IOUT
7/11
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