SPX1117T-L-3-3 Просмотр технического описания (PDF) - Signal Processing Technologies
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SPX1117T-L-3-3 Datasheet PDF : 16 Pages
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TABLE 1
PC BOARD
mm2
2500
2500
2500
2500
2500
1600
2500
2500
1600
900
900
APPLICATION INFORMATION: Continued
TOPSIDE COPPER BACKSIDE COPPER
mm2
2500
1250
950
2500
1800
600
1250
915
600
240
240
mm2
2500
2500
2500
0
0
1600
0
0
0
900
0
THERMAL RESISTANCE
JUNC. TO AMB.
°C/W
46
47
49
51
53
55
58
59
67
72
85
Output Voltage
The output of the adjustable regulator can be set
to any voltage between 1.25V and 15V. The
value of V can be quickly approximated using
OUT
the formula
VOUT=1.25 *(R1 + R2)/R1.
A small correction to this formula is required
depending on the values of resistors R and R ,
1
2
since the adjustable pin current (approx 50µA)
flows through R2. When IADJ is taken into ac-
count, the formula becomes
VOUT = VREF(1+ (R2/R1)) + IADJ * R2,
where
V =1.25V.
REF
Layout Considerations
Parasitic line resistance can degrade load regu-
lation. In order to avoid this, connect R directly
1
to V as illustrated in Figure 25. For the same
OUT
reason, R should be connected to the negative
2
side of the load.
V IN
IN
4.7µF + C 1
SPX1117
ADJ
IOUT =
VREF
R1
OUT
VOUT
C2
R1
IOUT
LOAD
VIN
IN
4.7µF + C1
SPX1117
ADJ
I ADJ
50µA
VOUT = V REF (1+R 2 /R1) +IADJ R 2
OUT
VREF R1
VOUT
C2
R2
Figure 21. Current Source
Figure 22. Typical Adjustable Regulator
Apr 20-07 Rev B
SPX1117 800mA Low Dropout Voltage Regulator
8
© 2007 Sipex Corporation
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