LX8585-33CP-TR [MICROSEMI]

Fixed Positive LDO Regulator;
LX8585-33CP-TR
型号: LX8585-33CP-TR
厂家: Microsemi    Microsemi
描述:

Fixed Positive LDO Regulator

输出元件 调节器
文件: 总10页 (文件大小:708K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
LX8585-xx / LX858A-xx  
®
4.6A Low Dropout Positive Regulators  
TM  
PRODUCTION DATA SHEET  
KEY FEATURES  
DESCRIPTION  
ƒ Three Terminal Adjustable or  
Fixed Output  
ƒ Guaranteed < 1.2V headroom  
@ 4.6A (LX8585A)  
ƒ Guaranteed < 1.4V headroom  
@ 4.6A (LX8585)  
ƒ Guaranteed < 1.3V Headroom  
@ 3A  
The LX8585/85A Series ICs are short-circuit current. On-chip thermal  
low dropout three-terminal regulators limiting provides protection against any  
with a minimum of 4.6A output possible overload that would create  
current. Pentium® Processor and excessive junction temperatures. The  
Power PCTM applications requiring LX8585/85A family is available in both  
fast transient response are ideally through-hole  
and  
surface-mount  
suited for this product family. The versions of the industry standard 3-pin  
LX8585A is guaranteed to have < TO-220 / TO-263 power packages.  
ƒ Output 6A  
Minimu
1.2V at 4.6A, while the LX8585 are  
The  
LX1431  
Programmable  
Fast TrRespse  
VoltaefereInitial  
uracy  
ƒ Ot Short Circuit Protection  
ƒ Builthmal Shutdown  
specified for 1.4V, making them ideal Reference and LX8585A Series  
to provide well regulated outputs of products offer precision output voltage  
2.5V to 3.6V using a 5V input supply. and are ideal for use in VRE  
Fixed versions are also available and applications (see application below).  
specified in the Available Options For higher current applications, see the  
table below. Current limit is trimmed LX8584 data sheet.  
above 4.6A to ensure adequate output  
current and controlled  
APPLICATIONS  
ƒ ntium Processor Supplies  
Power PC Supplies  
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.co
ƒ Microprocessor Supplies  
ƒ Low Voltage Logic Supplies  
ƒ Battery Powered Circuit  
ƒ Post Regulator for Switching  
Supply  
PRODUCT HIGHLIGHT  
THE APPLICATION OF THE LX8585A & LX1431 IN A  
75 & 166 MHZ P54C PROCESSORSUSING 5V CACH
V
4.6A  
ƒ CYRIX® 6x86™ Supplies  
ƒ AMD-K5™ Supplies  
O
PLACE IN µ
3
2
(See Table Below)  
VIN  
VOUT  
5V  
2x  
LX8585A  
330 µ F, 6.3V  
1k Ω  
Low ESR  
Oscon Typ
from Sany
Available Options Per Part Number  
ADJ  
1
0.01 µF  
1kΩ  
Part #  
Output Voltage  
Adjustable  
1.5V  
1x 6  
10V  
250pF  
2
LX8585/85A-00  
LX8585/85A-15  
LX8585/85A-33  
VX TYPE  
TPS  
1
µP  
Load  
COL  
3
3.3V  
V+  
220 µF  
10V  
R
Low ESR  
Sanyo  
from  
LX1431  
Other voltage options may be available.  
Please contact factory for details.  
1µ F x 10  
SMD  
0
JP1  
VOUT  
3.50  
3.38  
Open  
Typical Application  
120 / 166MHz, VRE, 5V Cache  
75/90/100/133MHz, STND, 5V Cache  
Thick traces represent high current traces which must be low resistance / low inductance  
traces in order to achieve good transient response.  
PACKAGE ORDER INFO  
Plastic TO-220  
3-Pin  
Plastic TO-263  
3-Pin  
Dropout  
Voltage  
P
DD  
TA (°C)  
RoHS Compliant  
RoHS Compliant  
Transition DC: 0543  
Transition DC: 0535  
1.4V  
1.2V  
LX8585-xxCP  
LX8585A-xxCP  
LX8585-xxCDD  
LX8585A-xxCDD  
0 to 125  
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX8585-15CDD-TR)  
Copyright © 1997  
Rev. 2.2a, 2005-11-10  
Microsemi  
Integrated Products Division  
Page 1  
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570  
LX8585-xx / LX858A-xx  
®
4.6A Low Dropout Positive Regulators  
TM  
PRODUCTION DATA SHEET  
ABSOLUTE MAXIMUM RATINGS  
PACKAGE PIN OUT  
TAB is GND  
Power Dissipation....................................................................................Internally Limited  
Input Voltage .................................................................................................................10V  
Input to Output Voltage Differential..............................................................................10V  
Maximum Operating Junction Temperature .............................................................. 150°C  
Storage Temperature Range.........................................................................-65°C to 150°C  
Peak Package Temp. for Solder Reflow (40 seconds max. exposure)............ 260°C (+0 -5)  
3
2
1
VIN  
VOUT  
ADJ/GND*  
P PACKAGE  
(Top View)  
TAB
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to  
Ground. Currents are positive into, negative out of specified terminal.  
V
2
J / GND*  
THERMAL DATA  
DD PACKAGE  
op View)  
PlasticTO-220 3-Pin  
P
* Pin 1 for fixed voltage versions  
oHS 100% Matte Tin Lead Finish  
THERMAL RESISTANCE-JUNCTION TO TAB, θJT  
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA  
3.0°C/W  
60°C/W  
Plastic TO-263 3-Pin  
DD  
THERMAL RESISTANCE-JUNCTION TO TAB, θJT  
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA  
3.0°C/
C/W  
Junction Temperature Calculation: TJ = TA + (PD x θJA).  
The θJA numbers are guidelines for the thermal performance of the device/l of the  
above assume no ambient airflow.  
Copyright © 1997  
Rev. 2.2a, 2005-11-10  
Microsemi  
Page 2  
Integrated Products Division  
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570  
LX8585-xx / LX858A-xx  
®
4.6A Low Dropout Positive Regulators  
TM  
PRODUCTION DATA SHEET  
ELECTRICAL CHARACTERISTICS  
Unless otherwise specified, the following specifications apply over the operating ambient temperature 0°C TA 70°C except where  
otherwise noted and the following test conditions:.  
LX8585/85A  
Parameter  
Symbol  
Test Conditions  
Units  
Min  
Typ  
Max  
`
LX8585-00 / 8585A-00 (ADJUSTABLE)  
Reference Voltage  
IOUT = 10mA, TA = 25°C  
10mA < IOUT < 4.6A, 1.5V < (VIN – VOUT), VIN < 7V,  
P < PMAX  
1.238  
1.225  
1.250  
1.262  
.275  
VREF  
V
Line Regulation (Note 2)  
Load Regulation (Note 2)  
Thermal Regulation  
VREF(VIN) IOUT = 10mA, 1.5V < (VIN – VOUT), VIN < 7V  
VREF(IOUT VIN – VOUT = 3V, 10mA < IOUT < 4.6V  
VOUT (Pwr) TA = 25°C, 20ms pulse  
VOUT = 3.3V, f = 120Hz, COUT = 100µF Tantalum
IN = 5V, CADJ = 10µF,  
0.20  
0
0
%
%
%/W  
)
Ripple Rejection (Note 3)  
V
83  
dB  
TA = 25°C, IOUT = 4.6V  
Adjust Pin Current  
IADJ  
100  
5
µA  
µA  
10mA < IOUT < 4.6A, 1.5V < (VIN – VOU
VIN < 7V  
Adjust pin Current Change  
IADJ  
0.2  
VREF = 1%, IOUT = 4.6A  
VREF = 1%, IOUT = 3A  
VREF = 1%, IOUT = 4.6A  
VIN < 7V  
1.2  
1.1  
1.1  
2
4.6  
0.25  
0.3  
1.4  
1.3  
1.2  
10  
6
LX8585  
LX8585A  
Dropout Voltage  
V  
V
Minimum Load Current  
IOUT(MIN)  
IOUT(MAX)  
VOUT(t)  
VOUT(t)  
mA  
A
%
Maximum Output Current (Note 4)  
Temperature Stability (Note 3)  
Long Term Stability (Note 3)  
RMS Output Noise  
1.4V < (VIN – VOUT), VIN < 7V  
TA = 125°C, 100
1
%
VOUT(RMS)  
TA = 125°C, 10
0.003  
%
(% of VOUT)(Note 3)  
`
LX8585-15 / 8585A-15 (1.5V FIXED)  
VIN = 5V, IOUT = 0
4.7N < 10V, 0UT < 7A, TA = 25°C, P  
< MAX  
1.485  
1.470  
1.50  
1.50  
1.515  
1.530  
Output Voltage (Note 4)  
VOUT  
V
5 < V
IN < 1
1
1
3
5
mV  
Line Regulation (Note 2)  
VOUT (VIN)  
Load Regulation (Note 2)  
Thermal Regulation (Note 3)  
VOUT(IOUT  
VTA = 25°s pulse  
)
VIN = 5V, 10mIOUT < IOUT(MAX)  
2.5  
0.01  
7
0.02  
mV  
% / W  
UT = 100µF (Tantalum), IOUT = 4.6A,  
Ripple Rejection (Note 3)  
Quiescent Current  
65  
83  
dB  
25°C  
< IOUT < IOUT(MAX), 4.75V < VIN < 10V  
UT = 1%, IOUT < IOUT(MAX), VIN - VOUT < 7V  
VOUT = 1%, IOUT < 3A, VIN - VOUT < 7V  
VOUT = 1%, IOUT < IOUT(MAX), VIN - VOUT < 7V  
4
10  
1.4  
1.3  
1.2  
mA  
1.2  
1.1  
1.1  
0.25  
0.3  
Dropout Voltage  
V
Temperature S
Long Term Sta
RMS Output N
VOUT(T)  
VOUT(t)  
%
%
TA = 125°C, 1000hrs  
1
VOUT(RMS)  
TA = 25°C, 10Hz < f < 10kHz  
0.003  
%
V
OUT)(NOTE 3)  
Note 2: Regulation iant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating  
effects are covere specification for thermal regulations.  
Note 3: These parameters, although guaranteed, are not tested in production.  
Note 4: IOUT(MAX) is measured under the condition that VOUT is forced below its nominal value by 100mV.  
Copyright © 1997  
Rev. 2.2a, 2005-11-10  
Microsemi  
Integrated Products Division  
Page 3  
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570  
LX8585-xx / LX858A-xx  
®
4.6A Low Dropout Positive Regulators  
TM  
PRODUCTION DATA SHEET  
APPLICATION CIRCUITS  
LX8585/85A  
OUT  
LX8585/85A  
OUT  
(Note A)  
VIN  
5V  
VOUT  
IN  
VIN  
(Note A)  
IN  
VOUT**  
R1  
121Ω  
1%  
ADJ  
ADJ  
R1  
121Ω  
10µF  
150µF  
C2  
100µF  
C1*  
10µF  
R2  
365Ω  
1%  
R2  
1k  
C1  
* C1 improves ripple rejection.  
XC should beR1 at ripple  
frequency.  
10µF*  
Figure 1 – Improving Ripple Rejection  
Needed if devicfrom filtors.  
R
R1  
** VOUT = 1.25V 1 +  
Figure 2 V Adjule Regulator  
LX8585/85A  
OUT  
VIN  
(Note A)  
IN  
5V  
ADJ  
1
1%  
100µF  
10µF  
1k  
TTL  
Output  
2N3904  
365Ω  
1%  
5V Regulator With Shutdown  
LX8585-33/85A-33  
IN  
OUT  
3.3V  
GND  
or 100µum  
Min. 15µF Tantalum or  
100µF Aluminum capacitor.  
May be increased without  
limit. ESR must be less  
than 50mΩ.  
Figure 4 – Fixed 3.3V Output Regulator  
Note A: VIN(MIN) = (Intended VOUT) + (VDROPOUT(MAX)  
)
Copyright © 1997  
Rev. 2.2a, 2005-11-10  
Microsemi  
Integrated Products Division  
Page 4  
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570  
LX8585-xx / LX858A-xx  
®
4.6A Low Dropout Positive Regulators  
TM  
PRODUCTION DATA SHEET  
APPLICATION NOTE  
Minumum Load  
(Larger resistor)  
The LX8585/85A Series ICs are easy to use Low-Dropout  
(LDO) voltage regulators. They have all of the standard self-  
protection features expected of a voltage regulator: short circuit  
protection, safe operating area protection and automatic thermal  
shutdown if the device temperature rises above approximately  
165°C.  
Power Supply  
IN  
OUT  
LX8585/85A  
Full Load  
(Smaller resistor)  
ADJ  
RDSON<< RL  
1 sec  
10ms  
Use of an output capacitor is REQUIRED with the LX8585/85A  
series. Please see the table below for recommended minimum  
capacitor values.  
Star Ground  
Figure 5 – Dynamic Input
OVERLOAD RECOVERY  
These regulators offer a more tightly controlled reference voltage  
tolerance and superior reference stability when measured against  
the older pin-compatible regulator types that they replace.  
Like almost all IC power ulors, t8585/8regulators  
are equipped with Safe Og Area A) ection. The  
SOA circuit limits the remaximum utput current to  
progressively lower values ae input-to-output voltage  
difference increases. iting the m output current, the  
SOA circuit keepof powthat is dissipated in the  
regulator itself wmits for all values of input-to-output  
voltwithin ratinange of the regulator. The  
LX858A SOA ection stem is designed to be able to  
supply soutput for all values of input-to-output  
voltage, up tdevice breakdown voltage.  
STABILITY  
The output capacitor is part of the regulator’s frequency  
compensation system. Many types of capacitors are available, with  
different capacitance value tolerances, capacitance temperature  
coefficients, and equivalent series impedances. For all operating  
conditions, connection of a 220μF aluminum electrolytic capacitor  
or a 47μF solid tantalum capacitor between the output terminal  
and ground will guarantee stable operation.  
If a bypass capacitor is connected between the output voltage  
adjust (ADJ) pin and ground, ripple rejection will be improved  
(please see the section entitled “RIPPLE REJECTION”). When  
ADJ pin bypassing is used, the required output capacitor value  
increases. Output capacitor values of 220μF (aluminum) or 47μF  
(tantalum) provide for all cases of bypassing the ADJ pin. If an  
ADJ pin bypass capacitor is not used, smaller outpucitor  
values are adequate. The table below shows rommende
minimum capacitance values for stable operation  
some cions, a correctly operating SOA circuit may  
power pply system from returning to regulated  
er removal of an intermittent short circuit at the  
regulator. This is a normal mode of operation which  
n most similar products, including older devices such  
eries regulators. It is most likely to occur when the  
power system input voltage is relatively high and the load  
impedance is relatively low.  
When the power system is started “cold”, both the input and  
output voltages are very close to zero. The output voltage closely  
follows the rising input voltage, and the input-to-output voltage  
difference is small. The SOA circuit therefore permits the  
regulator to supply large amounts of current as needed to develop  
the designed voltage level at the regulator output.  
Input  
Output  
Adj  
10µF 15µF Tantalum, 0µF A
No
10µF 47µF Tantalum, 2F
15µF  
To ensure good transieonse froply system  
under rapidly chload s, designers  
generally use sevs connein parallel. Such  
an arrangement e effects of the parasitic  
resistance (ESR) that are present in all  
capacitors. Cost sufficiently limit ESR and  
ESL effects genecapacitance values in the  
range of hundreds to icrofarads, which is more than  
adequate to meet regulatout capacitor specifications. Output  
capacitance values may be increased without limit.  
Now consider the case where the regulator is supplying  
regulated voltage to a resistive load under steady state conditions.  
A moderate input-to-output voltage appears across the regulator  
but the voltage difference is small enough that the SOA circuitry  
allows sufficient current to flow through the regulator to develop  
the designed output voltage across the load resistance. If the  
output resistor is short circuited to ground, the input-to-output  
voltage difference across the regulator suddenly becomes larger  
by the amount of voltage that had appeared across the load  
resistor. The SOA circuit reads the increased input-to-output  
voltage, and cuts back the amount of current that it will permit the  
regulator to supply to its output terminal. When the short circuit  
across the output resistor is removed, all the regulator output  
current will again flow through the output resistor. The maximum  
current that the regulator can supply to the resistor will be limited  
by the SOA circuit, based on the large input-to-output voltage  
across the regulator at the time the short circuit is removed from  
the output.  
The circuit shown in Figure 5 can be used to observe the  
transient response characteristics of the regulator in a power  
system under changing loads. The effects of different capacitor  
types and values on transient response parameters, such as  
overshoot and undershoot, can be compared quickly in order to  
develop an optimum solution.  
Copyright © 1997  
Rev. 2.2a, 2005-11-10  
Microsemi  
Page 5  
Integrated Products Division  
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570  
LX8585-xx / LX858A-xx  
®
4.6A Low Dropout Positive Regulators  
TM  
PRODUCTION DATA SHEET  
APPLICATION NOTE  
OVERLOAD RECOVERY (continued)  
LX8585/85A  
OUT  
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.  
IN  
VIN  
VOUT  
ADJ  
VREF  
R1  
R2  
IADJ  
50µA  
RIPPLE REJECTION  
R2  
R1  
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:  
VOUT = VREF 1 +  
+ IADJ
Figure 6 – Bajustable
LOAD REGULATION  
C = 1 / (6.28 * FR * R1)  
where: C the value of the capacitor in Farads; select an equal  
or larger standard value.  
Because the LX8585/85A regulare ree-terminal devices,  
it is not possible e true load sensing. Load  
regulation will be he resistance of the wire connecting  
the rulator to The ta sheet specification for load  
regulis meaat the ttom of the package. Negative  
side senis a trlvin nnection, with the bottom of the  
output divieturned te negative side of the load. Although  
it may not mmediately obvious, best load regulation is  
when tp of the resistor divider, (R1), is connected  
the casof the regulator, not to the load. This is  
Figure 7. If R1 were connected to the load, the  
tance between the regulator and the load would be:  
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 ence  
voltage:  
R2 + R1  
RPeff = RP  
*
R1  
M = VOUT/VREF  
where: RP Actual parasitic line resistance.  
where: M a multiplier for the ripple seen when thpin is  
optimally bypassed.  
When the circuit is connected as shown in Figure 7, the parasitic  
resistance appears as its actual value, rather than the higher RPeff  
VREF = 1.25V.  
For example, if VOUT = 2.5V the t r
M = 2.5V/1.25V= 2  
Output ripple will be twie as bad as e ADJ pin  
were to be bypassed a propd capacitor.  
RP  
Parasitic  
LX8585/85A  
Line Resistance  
OUT  
IN  
VIN  
ADJ  
Connect  
R1 to Case  
of Regulator  
OUTPUT VOLT
The LX8585/1.25V reference voltage  
between the ouminal (See Figure 6). By  
placing a resistotwo terminals, a constant  
current is caused tand down through R2 to set  
the overall output voly this current is the specified  
minimum load current of 10mA. Because IADJ is very small and  
constant when compared with the current through R1, it represents  
a small error and can usually be ignored.  
R1  
R2  
RL  
Connect  
R2  
to Load  
Figure 7 – Connections For Best Load Regulation  
Copyright © 1997  
Rev. 2.2a, 2005-11-10  
Microsemi  
Page 6  
Integrated Products Division  
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570  
LX8585-xx / LX858A-xx  
®
4.6A Low Dropout Positive Regulators  
TM  
PRODUCTION DATA SHEET  
APPLICATION NOTE  
can be used, as long as its added contribution to thermal  
LOAD REGULATION (continued)  
resistance is considered. Note that the case of all devices in this  
series is electrically connected to the output.  
Even when the circuit is configured optimally, parasitic  
resistance can be a significant source of error. A 100 mil (2.54  
mm) wide PC trace built from 1 oz. copper-clad circuit board  
material has a parasitic resistance of about 5 milliohms per inch of  
its length at room temperature. If a 3-terminal regulator used to  
supply 2.50 volts is connected by 2 inches of this trace to a load  
which draws 5 amps of current, a 50 millivolt drop will appear  
between the regulator and the load. Even when the regulator  
output voltage is precisely 2.50 volts, the load will only see 2.45  
volts, which is a 2% error. It is important to keep the connection  
between the regulator output pin and the load as short as possible,  
and to use wide traces or heavy-gauge wire.  
Example  
Given: VIN = 5V  
V
OUT = 2.8V, IOUT = 5.0A  
Ambient Temp. TA = 50°C  
ΘJT = 2.7°C/W for TO-220  
R
300 ft/min airfloavailable  
Find:  
Proper Heat SinIC’s ion terature  
below 125°C.**  
Solution: The junction temperat:  
TJ = PD (RΘ+ RΘCS + R+
Where: PD Diser  
The minimum specified output capacitance for the regulator  
should be located near the regulator package. If several capacitors  
are used in parallel to construct the power system output  
capacitance, any capacitors beyond the minimum needed to meet  
the specified requirements of the regulator should be located near  
the sections of the load that require rapidly-changing amounts of  
current. Placing capacitors near the sources of load transients will  
help ensure that power system transient response is not impaired  
by the effects of trace impedance.  
RΘJT istance from the junction to the  
mountithe kage  
CS Tal resince through the interface  
een the he surface on which it is mounted.  
(1.W at 6 in-lbs mounting screw torque).  
RΘSA ermal resistance from the mounting surface  
To maintain good load regulation, wide traces should be used on  
the input side of the regulator, especially between the input  
capacitors and the regulator. Input capacitor ESR must be small  
enough that the voltage at the input pin does not drop below VIN  
(MIN) during transients.  
ambie(thermal resistance of the heat sink).  
heat sink temperature.  
TC  
TS  
TA  
R
R
R
JT  
CS  
SA  
V
IN (MIN) = VOUT + VDROPOUT (MAX)  
First, find the maximum allowable thermal resistance of the heat  
sink:  
where: VIN (MIN) the lowest allowable instantanevo
the input pin.  
TJ TA  
VOUT the designed output voltaghe power supp
system.  
RΘSA  
=
(RΘJT + RΘCS  
)
PD  
VIN(MAX) VOUT  
= 11.0W  
VDROPOUT  
installed regulator.  
the spge for the  
(MAX)  
PD  
=
(
)
IOUT = (5.0V 2.8V) * 5.0A  
THERMAL CONSIS  
The LX8585/85internwer and thermal  
limiting circuitrach devce under overload  
conditions. For ad conditions, however,  
maximum junctimust not be exceeded. It is  
important to give to all sources of thermal  
resistance from junchis includes junction to case,  
case to heat sink interfaeat sink thermal resistance itself.  
Junction-to-case thermal resistance is specified from the IC  
junction to the back surface of the case directly opposite the die.  
This is the lowest resistance path for heat flow. Proper mounting is  
required to ensure the best possible thermal flow from this area of  
the package to the heat sink. Thermal compound at the case-to  
heat-sink interface is strongly recommended. If the case of the  
device must be electrically isolated, a thermally conductive spacer  
125°C 50°C  
RΘSA  
=
(2.7°C/W + 1.0°C/W)  
(5.0V 2.8V) * 5.0A  
= 3.1°C/W  
Next, select a suitable heat sink. The selected heat sink must  
have RΘSA < 3.1°C/W. Thermalloy heatsink 6296B has RΘSA  
3.0°C/W with 300ft/min airflow.  
Finally, verify that junction temperature remains within  
specification using the selected heat sink:  
=
T = 11W(2.7°C/W + 1.0°C/W + 3.0°C/W) + 50°C = 124°C  
J
**Although the device can operate up to 150°C junction, it is  
recommended for long term reliability to keep the junction  
temperature below 125°C whenever possible.  
Copyright © 1997  
Rev. 2.2a, 2005-11-10  
Microsemi  
Page 7  
Integrated Products Division  
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570  
LX8585-xx / LX858A-xx  
®
4.6A Low Dropout Positive Regulators  
TM  
PRODUCTION DATA SHEET  
PACKAGE DIMENSIONS  
3-Pin Plastic TO-220  
P
B
S
MILLIMETERS  
INCHES  
Dim  
MIN  
14.22  
9.65  
3.56  
0.51  
3.53  
MAX  
15.88  
10.67  
4.83  
1.14  
MIN  
MAX  
0.625  
0.420  
0.190  
45  
.161  
F
T
Q
A
B
C
D
F
0.560  
0  
0
U
A
G
H
J
K
2.54 BC  
0.100 BSC  
6.35  
14  
0.250  
0.045  
0.580  
0.050  
C
0.
1
1
012  
0.500  
0.045  
1
2
3
14.73  
R
H
1.
N
Q
R
5TY
0.200 TYP  
2.54  
3  
1.4  
5.84  
0.508  
3.05  
2.92  
1.40  
6.86  
1.14  
0.100  
0.080  
0.045  
0.230  
0.020  
0.120  
0.115  
0.055  
0.270  
0.045  
K
D
Note:  
L
J
1. Dimensions do not include mold flash or protrusions;  
these shall not exceed 0.155mm(.006”) on any side.  
Lead dimension shall not include solder coverage.  
G
N
Copyright © 1997  
Rev. 2.2a, 2005-11-10  
Microsemi  
Page 8  
Integrated Products Division  
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570  
LX8585-xx / LX858A-xx  
®
4.6A Low Dropout Positive Regulators  
TM  
PRODUCTION DATA SHEET  
PACKAGE DIMENSIONS  
3-Pin Plastic TO-263  
DD  
I
A
MILLIMETERS  
INCHES  
D
Dim  
MIN  
10.03  
8.51  
4.19  
1.14  
0.330  
1.19  
2.41  
2
MAX  
10.67  
9.17  
4.59  
1.40  
1  
1
2.6
2.79  
1.65  
05  
.87  
MIN  
MAX  
0.420  
0.361  
0.181  
055  
0.020  
0.053  
0.104  
0.110  
0.065  
0.010  
0.625  
A
B
C
D
E
F
G
H
I
J
0.395  
45  
3  
0.047  
0095  
.090  
C
B
K
M
N
H
0
M
N
14
0.575  
E
F
7°  
3°  
7°  
3°  
G
ns do not include mold flash or protrusions; these  
exceed 0.155mm(.006”) on any side. Lead  
n shall not include solder coverage.  
0° -8°  
J
Seating Plane  
Copyright © 1997  
Rev. 2.2a, 2005-11-10  
Microsemi  
Page 9  
Integrated Products Division  
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570  
LX8585-xx / LX858A-xx  
®
4.6A Low Dropout Positive Regulators  
TM  
PRODUCTION DATA SHEET  
NOTES  
PRODUCTION DATA – Information contained in this document is proprietary to  
Microsemi and is current as of publication date. This document may not be modified in  
any way without the express written consent of Microsemi. Product processing does not  
necessarily include testing of all parameters. Microsemi reserves the right to change the  
configuration and performance of the product and to discontinue product at any time.  
Copyright © 1997  
Rev. 2.2a, 2005-11-10  
Microsemi  
Integrated Products Division  
Page 10  
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570  

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