SPX1117T Exar Corporation, SPX1117T Datasheet - Page 8

• Manufacturer Part Number: SPX1117T
• Description: 800mA Low Dropout Voltage Regulator
• Manufacturer: Exar Corporation

TABLE 1
Output Voltage
The output of the adjustable regulator can be
set to any voltage between 1.25V and 15V.
The value of V
using the formula
A small correction to this formula is required
depending on the values of resistors R
since the adjustable pin current (approx 50 A)
flows through R
account, the formula becomes
Rev. 3/4/02
Figure 21. Current Source
PC BOARD
2500
2500
2500
2500
2500
1600
2500
2500
1600
900
900
mm
2
V
OUT
OUT
=1.25 *(R
2
. When I
can be quickly approximated
TOPSIDE COPPER
1
ADJ
2500
1250
2500
1800
1250
mm
+ R
950
600
915
600
240
240
is taken into
2
2
)/R
1
.
SPX1117 800mA Low Dropout Voltage Regulator
1
and R
BACKSIDE COPPER
2
,
2500
2500
2500
1600
900
8
mm
0
0
0
0
0
0
2
where
Layout Considerations
regulation. In order not to affect the behavior
of the regulator, it is best to connect R
case as illustrated in Figure 25. For the same
reason, R
tive side of the load.
Parasitic line resistance can degrade load
Figure 22. Typical Adjustable Regulator
V
OUT
2
= V
should be connected to the nega-
REF
THERMAL RESISTANCE
V
(1+ (R
REF
JUNC. TO AMB.
=1.25V.
© Copyright 2002 Sipex Corporation
2
/R
1
C/W
)) + I
46
47
49
51
53
55
58
59
67
72
85
ADJ
* R
1
2
to the
,