LT1946A Ver la hoja de datos (PDF) - Linear Technology
Número de pieza
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Fabricante
LT1946A Datasheet PDF : 12 Pages
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APPLICATIO S I FOR ATIO
100
50
0
–50
100
0
1k
10k
100k
1M
FREQUENCY (Hz)
1946A FO5a
LT1946A
Setting Output Voltage
To set the output voltage, select the values of R1 and R2
(see Figure 1) according to the following equation:
R1 =
R2
VOUT
1.25V
–
1
A good range for R2 is from 5k to 30k.
Layout Hints
The high speed operation of the LT1946A demands careful
attention to board layout. You will not get advertised
performance with careless layouts. Figure 6 shows the
recommended component placement for a boost con-
verter.
–100
58°
–180
–200
100
1k
10k
100k
1M
FREQUENCY (Hz)
1946A FO5b
Figure 5. Gain and Phase Plots of Figure 1 Circuit
Diode Selection
A Schottky diode is recommended for use with the LT1946A.
The Microsemi UPS120 is a very good choice. Where the
input to output voltage differential exceeds 20V, use the
UPS140 (a 40V diode). These diodes are rated to handle an
average forward current of 1A. For applications where the
average forward current of the diode is less than 0.5A, an
ON Semiconductor MBR0520 diode can be used.
GROUND PLANE
CSS
C1
CC
+
VIN
RC
1
8
R1
2
7
LT1946A
L1
R2
3
6
SHUTDOWN
4
5
MULTIPLE
VIAs
GND
C2
VOUT
19949 F04
NOTE: DIRECT HIGH CURRENT PATHS USING WIDE PC TRACES. MINIMIZE TRACE AREA AT
PIN 1(VC) AND PIN 2(FB). USE MULTIPLE VIAS TO TIE PIN 4 COPPER TO GROUND PLANE. USE
VIAS AT ONE LOCATION ONLY TO AVOID INTRODUCING SWITCHING CURRENTS INTO THE
GROUND PLANE.
Figure 6. Recommended Component
Placement for Boost Converter
sn1946a 1946afs
9
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