|
|
PDF LX8554-33 Data sheet ( Hoja de datos )
| Número de pieza | LX8554-33 | |
| Descripción | 5A EXTREMELY LOW DROPOUT POSITIVE REGULATORS | |
| Fabricantes | Microsemi Corporation | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LX8554-33 (archivo pdf) en la parte inferior de esta página. Total 7 Páginas | ||
|
No Preview Available !
T H E I N F I N I T E P O W E R O F I N N O VAT I O N
L I N D O C #: 8554
LX8554-xx
5A EXTREMELY LOW DROPOUT POSITIVE REGULATORS
PR O D U C T I O N D ATA S H E E T
DESCRIPTION
The LX8554 series ICs are very low drop-
out three-terminal positive regulators with
5A rated output current. This product fam-
ily is ideally suited for Pentium® Proces-
sor and Power PCTM applications requir-
ing fast transient response. The LX8554
is guaranteed to have a dropout volt-
age under 1V at 5A load, making it ideal
to provide well-regulated outputs of 2.5V
to 3.6V with input supply as low as 4.75V.
Fixed versions are also available and are
specified in the Available Options table
below.
Current limit is trimmed above 5.1A to
ensure adequate output current and con-
trolled short-circuit current. On-chip ther-
mal limiting provides protection against
any combination of overload that would
create excessive junction temperatures.
The LX8554 series products are avail-
able in both through-hole and surface-
mount versions of industry standard 3-pin
TO-220 / TO-263 power packages.
The LX8554 family of products are ideal
for use in multiple processor applications
where output voltage is jumper selected.
The LX8554 ICs offer precision output as
well as low supply operation (see appli-
cation below). For higher current appli-
cations see the LX8584 series of products.
PRODUCT HIGHLIGHT
TYPICAL APPLICATION OF THE LX8554 IN A FLEXIBLE MOTHERBOARD WITH
OUTPUT VOLTAGE SELECTABLE VIA JUMPERS "JP1" AND "JP2"
VIN ³ 4.75
1500µF, 6.3V
Sanyo MVGX Series
LX8554
IN OUT
ADJ
VREF
200W
1%
R1
121W
1%
VO
(See Table Below)
3x 1500µF
6.3V
Sanyo
MVGX Series
R2
13W
1%
JP1
VOUT = VREF
1
+
R2
R1
+ IADJ R2
14.7W
1%
JP2
KEY FEATURES
s THREE-TERMINAL ADJUSTABLE OR FIXED
OUTPUT
s GUARANTEED ≤ 1V HEADROOM AT 5A
s OUTPUT CURRENT OF 5A
p FAST TRANSIENT RESPONSE
p 1% VOLTAGE REFERENCE INITIAL
ACCURACY
p OUTPUT SHORT-CIRCUIT PROTECTION
p BUILT-IN THERMAL SHUTDOWN
s EVALUATION BOARD AVAILABLE:
REQUEST LXE9001 EVALUATION KIT
A P P L I C AT I O N S
s PENTIUM PROCESSOR SUPPLIES
s POWER PC SUPPLIES
s MICROPROCESSOR SUPPLIES
s LOW VOLTAGE LOGIC SUPPLIES
s BATTERY POWERED CIRCUIT
s POST REGULATOR FOR SWITCHING SUPPLY
AVAILABLE O PTIONS PER PAR T #
Part #
Output
Voltage
LX8554-00
Adjustable
LX8554-33
3.3V
Other voltage options may be available —
Please contact factory for details.
JP1
Open
Open
Short
JP2
Open
Short
Short
OUTPUT VOLTAGE
3.6V
3.45V
3.3V
Copyright © 1997
Rev. 1.1 1/97
PACKAGE ORDER INFORMATION
TA (°C)
P
Plastic TO-220
3-pin
DD
Plastic
3-pin
T0-263
0 to 125
LX8554-xxCP
LX8554-xxCDD
Note: All surface-mount packages are available in Tape & Reel.
Append the letter "T" to part number. (i.e. LX8554-00CDDT)
"xx" refers to output voltage, please see table above.
FOR FURTHER INFORMATION CALL (714) 898-8121
11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841
1
1 page  
PRODUCT DATABOOK 1996/1997
5A EXTREMELY LOW DROPOUT POSITIVE REGULATORS
PR O D U C T I O N D ATA S H E E T
LX8554-xx
APPLICATION NOTES
OVERLOAD RECOVERY (continued)
If this limited current is not sufficient to develop the designed
voltage across the output resistor, the voltage will stabilize at some
lower value, and will never reach the designed value. Under these
circumstances, it may be necessary to cycle the input voltage down
to zero in order to make the regulator output voltage return to
regulation.
RIPPLE REJECTION
Ripple rejection can be improved by connecting a capacitor
between the ADJ pin and ground. The value of the capacitor should
be chosen so that the impedance of the capacitor is equal in
magnitude to the resistance of R1 at the ripple frequency. The
capacitor value can be determined by using this equation:
C = 1 / (6.28 * FR * R1)
where: C ≡ the value of the capacitor in Farads;
select an equal or larger standard value.
FR ≡ the ripple frequency in Hz
R1 ≡ the value of resistor R1 in ohms
At a ripple frequency of 120Hz, with R1 = 100Ω:
C = 1 / (6.28 * 120Hz * 100Ω) = 13.3µF
The closest equal or larger standard value should be used, in this
case, 15µF.
When an ADJ pin bypass capacitor is used, output ripple
amplitude will be essentially independent of the output voltage. If
an ADJ pin bypass capacitor is not used, output ripple will be
proportional to the ratio of the output voltage to the reference
voltage:
M = VOUT/VREF
where: M ≡ a multiplier for the ripple seen when the
ADJ pin is optimally bypassed.
VREF = 1.25V.
For example, if VOUT = 2.5V the output ripple will be:
M = 2.5V/1.25V= 2
Output ripple will be twice as bad as it would be if the ADJ pin
were to be bypassed to ground with a properly selected capacitor.
OUTPUT VOLTAGE
The LX8554 develops a 1.25V reference voltage between the output
and the adjust terminal (See Figure 2). By placing a resistor, R1,
between these two terminals, a constant current is caused to flow
through R1 and down through R2 to set the overall output voltage.
Normally this current is the specified minimum load current of 10mA.
Because IADJis very small and constant when compared with the current
through R1, it represents a small error and can usually be ignored.
LX8554
VIN IN OUT
ADJ
VREF
IADJ
50µA
VOUT = VREF
1
+
R2
R1
+ IADJ R2
VOUT
R1
R2
FIGURE 2 — BASIC ADJUSTABLE REGULATOR
LOAD REGULATION
Because the LX8554 is a three-terminal device, it is not possible to
provide true remote load sensing. Load regulation will be limited
by the resistance of the wire connecting the regulator to the load.
The data sheet specification for load regulation is measured at the
bottom of the package. Negative side sensing is a true Kelvin
connection, with the bottom of the output divider returned to the
negative side of the load. Although it may not be immediately
obvious, best load regulation is obtained when the top of the resistor
divider, (R1), is connected directly to the case of the regulator, not
to the load. This is illustrated in Figure 3. If R1 were connected to
the load, the effective resistance between the regulator and the load
would be:
RPeff = RP *
R2+R1
R1
where: RP ≡ Actual parasitic line resistance.
When the circuit is connected as shown in Figure 3, the parasitic
resistance appears as its actual value, rather than the higher RPeff.
LX8554
ParRaPsitic
Line Resistance
VIN IN
OUT
ADJ Connect
R1 to Case
of Regulator
R1
R2 RL
Connect
R2
to Load
FIGURE 3 — CONNECTIONS FOR BEST LOAD REGULATION
Copyright © 1997
Rev. 1.1 1/97
5
5 Page | ||
| Páginas | Total 7 Páginas | |
| PDF Descargar | [ Datasheet LX8554-33.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LX8554-33 | 5A EXTREMELY LOW DROPOUT POSITIVE REGULATORS | Microsemi Corporation |
| LX8554-33CDD | 5A EXTREMELY LOW DROPOUT POSITIVE REGULATORS | Microsemi Corporation |
| LX8554-33CP | 5A EXTREMELY LOW DROPOUT POSITIVE REGULATORS | Microsemi Corporation |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |