DataSheet8.cn


PDF ( 数据手册 , 数据表 ) FAN1587A

零件编号 FAN1587A
描述 3A Adjustable/Fixed Low Dropout Linear Regulator
制造商 Fairchild Semiconductor
LOGO Fairchild Semiconductor LOGO 


1 Page

No Preview Available !

FAN1587A 数据手册, 描述, 功能
www.fairchildsemi.com
FAN1587A
3A Adjustable/Fixed Low Dropout Linear Regulator
Features
• Fast transient response
• Low dropout voltage at up to 3A
• Load regulation: 0.05% typical
• Trimmed current limit
• On-chip thermal limiting
• Standard TO-220, TO-263, TO-263 center cut,
and TO-252 packages
Applications
• Pentium® Class GTL+ bus supply
• Low voltage logic supply
• Post regulator for switching supply
• 12V to 5V linear regulator
• 3.3V to 1.5V linear regulator
Description
The FAN1587A, FAN1587A-1.5, and FAN1587A-3.3 are low
dropout three-terminal regulators with 3A output current capa-
bility. These devices have been optimized for low voltage
applications including VTT bus termination, where transient
response and minimum input voltage are critical. The
FAN1587A is ideal for low voltage microprocessor applica-
tions requiring a regulated output from 1.5V to 3.6V with an
input supply of 12V or less. The FAN1587A-1.5 offers fixed
1.5V with 3A current capability for GTL+ bus VTT termina-
tion. The FAN1587A-3.3 offers fixed 3.3V current capability
for logic IC operation.
Current limit is trimmed to ensure specified output current and
controlled short-circuit current. On-chip thermal limiting pro-
vides protection against any combination of overload and
ambient temperature that would create excessive junction
temperatures.
The FAN1587A, FAN1587A-1.5, and FAN1587A-3.3 are
available in the industry-standard TO-220, TO-263, TO-263
center cut, and TO-252 (DPAK) power packages.
Typical Applications
VIN = 12V
22µF
+
FAN1587A
VIN VOUT
ADJ
VOUT = VREF (1+R2/R1)+IADJ*R2
VIN = 9V
22µF
+
FAN1587A-3.3
VIN VOUT
GND
R1
124
R2
768
9V at 3A
+
22µF
3.3V at 3A
+
22µF
65-1587-16
Pentium is a registered trademark of Intel Corporation.
REV. 1.0.5 11/10/03







FAN1587A pdf, 数据表
FAN1587A
PRODUCT SPECIFICATION
VIN +
FAN1587A
IN
C1
22µF
OUT
ADJ
IADJ
35µA
VREF
+
R1
VOUT
C2
22µF
R2
VOUT = VREF (1 + R2/R1) + IADJ (R2)
Figure 12. Basic Regulator Circuit
65-1587-14
Load Regulation
It is not possible to provide true remote load sensing because
the FAN1587A series are three-terminal devices. Load regu-
lation is limited by the resistance of the wire connecting the
regulators to the load. Load regulation per the data sheet
specification is measured at the bottom of the package.
For fixed voltage devices, negative side sensing is a true
Kelvin connection with the ground pin of the device returned
to the negative side of the load. This is illustrated in
Figure 13.
RP
FAN1587A-1.5, -3.3
PARASITIC
LINE RESISTANCE
VIN IN
OUT
GND
RL
65-1587-17
Figure 13. Connection for Best Load Regulation
For adjustable voltage devices, negative side sensing is a true
Kelvin connection with the bottom of the output divider
returned to the negative side of the load. The best load regu-
lation is obtained when the top of resistor divider R1 con-
nects directly to the regulator output and not to the load.
Figure 14 illustrates this point.
If R1 connects to the load, then the effective resistance
between the regulator and the load would be:
RP × (1 + R2/R1), RP = Parasitic Line Resistance
The connection shown in Figure 14 does not multiply RP by
the divider ratio. As an example, RP is about four milliohms
per foot with 16-gauge wire. This translates to 4mV per foot
at 1A load current. At higher load currents, this drop repre-
sents a significant percentage of the overall regulation. It is
important to keep the positive lead between the regulator and
the load as short as possible and to use large wire or PC
board traces.
RP
FAN1587A
PARASITIC
LINE RESISTANCE
VIN IN
OUT
ADJ
R1*
* CONNECT R1 TO CASE
CONNECT R2 TO LOAD
R2*
RL
65-1587-15
Figure 14. Connection for Best Load Regulation
Thermal Considerations
The FAN1587A series protect themselves under overload
conditions with internal power and thermal limiting circuitry.
However, for normal continuous load conditions, do not
exceed maximum junction temperature ratings. It is impor-
tant to consider all sources of thermal resistance from junc-
tion-to-ambient. These sources include the junction-to-case
resistance, the case-to-heat sink interface resistance, and the
heat sink resistance. Thermal resistance specifications have
been developed to more accurately reflect device tempera-
ture and ensure safe operating temperatures.
For example, look at using an FAN1587AT to generate 3A
@ 1.5V ± 2% from a 3.3V source (3.2V to 3.6V).
Assumptions:
• VIN = 3.6V worst case
• VOUT = 1.46V worst case
• IOUT = 3A continuous
• TA = 70°C
θCase-to-Ambient = 3°C/W (assuming both a heatsink and
a thermally conductive material)
The power dissipation in this application is:
PD = (VIN – VOUT) * (IOUT) = (3.6 – 1.46) * (3) = 6.42W
From the specification table:
TJ = TA + (PD) * (θCase-to-Ambient + θJC)
= 70 + (6.42) * (3 + 3) = 109°C
The junction temperature is below the maximum rating.
8 REV. 1.0.5 11/10/03














页数 14 页
下载[ FAN1587A.PDF 数据手册 ]


分享链接

Link :

推荐数据表

零件编号描述制造商
FAN1587A3A Adjustable/Fixed Low Dropout Linear RegulatorFairchild Semiconductor
Fairchild Semiconductor
FAN1587AD15X3A Adjustable/Fixed Low Dropout Linear RegulatorFairchild Semiconductor
Fairchild Semiconductor
FAN1587AD33X3A Adjustable/Fixed Low Dropout Linear RegulatorFairchild Semiconductor
Fairchild Semiconductor
FAN1587ADX3A Adjustable/Fixed Low Dropout Linear RegulatorFairchild Semiconductor
Fairchild Semiconductor

零件编号描述制造商
STK15C88256-Kbit (32 K x 8) PowerStore nvSRAMCypress Semiconductor
Cypress Semiconductor
NJM4556DUAL HIGH CURRENT OPERATIONAL AMPLIFIERNew Japan Radio
New Japan Radio
EL1118-G5 PIN LONG CREEPAGE SOP PHOTOTRANSISTOR PHOTOCOUPLEREverlight
Everlight


DataSheet8.cn    |   2020   |  联系我们   |   搜索  |  Simemap