|
|
PDF MIC39500-2.5BT Data sheet ( Hoja de datos )
| Número de pieza | MIC39500-2.5BT | |
| Descripción | 5A Low-Voltage Low-Dropout Regulator Advance Information | |
| Fabricantes | Micrel Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de MIC39500-2.5BT (archivo pdf) en la parte inferior de esta página. Total 8 Páginas | ||
|
No Preview Available !
MIC39500/39501
Micrel
MIC39500/39501
5A Low-Voltage Low-Dropout Regulator
Advance Information
General Description
The MIC39500 and MIC39501 is a 5A low-dropout linear
voltage regulator that provides a low-voltage, high-current
output with a minimum of external components. Utilizing
Micrel’s proprietary Super βeta PNP™ pass element, the
MIC39500 offers extremely low dropout (typically 400mV at
5A) and low ground current (typically 70mA at 5A).
The MIC39500 is ideal for PC Add-In cards that need to
convert from standard 5V or 3.3V, down to new, lower core
voltages. A guaranteed maximum dropout voltage of 500mV
over all operating conditions allows the MIC39500 to provide
2.5V from a supply as low as 3V. The MIC39500 also has fast
transient response, for heavy switching applications. The
device requires only 47µF of output capacitance to maintain
stability and achieve fast transient response
The MIC39500 is fully protected with overcurrent limiting,
thermal shutdown, reversed-battery and reversed-lead in-
sertion protection. The MIC39501 offers a TTL-logic-compat-
ible enable pin and an error flag that indicates undervoltage
and overcurrent conditions. The MIC39500 comes in the TO-
220 and TO-263 packages and is an ideal upgrade to older,
NPN-based linear voltage regulators.
Features
• 5A minimum guaranteed output current
• 500mV maximum dropout voltage over temperature
• 1% initial accuracy
• Low ground current
• Current limiting and thermal shutdown
• Reversed-battery and reversed-lead insertion protection
• Fast transient response
• TO-263 and TO-220 packages
• TTL/CMOS compatible enable pin (MIC39501 only)
• Error flag output (MIC39501 only)
Applications
• LDO linear regulator for PC add-in cards
• PowerPC™ power supplies
• High-efficiency linear power supplies
• SMPS post regulator
• Multimedia and PC processor supplies
• Low-voltage microcontrollers
• StrongARM™ processor supply
For applications requiring input voltage
greater than 16V, see the
MIC29500/1/2/3 family.
Ordering Information
Part Number
MIC39500-2.5BT
MIC39500-2.5BU
MIC39501-2.5BT
MIC39501-2.5BU
Voltage
2.5V
2.5V
2.5V
2.5V
Junction Temp. Range
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
Package
3-lead TO-220
3-lead TO-263
5-lead TO-220
5-lead TO-263
Typical Application
100KΩ
VIN
3.3V
1.0µF
MIC39500-2.5
IN OUT
GND
VOUT
2.5V
47µF
Enable
Shutdown
VIN
3.3V
1.0µF
MIC39501-2.5
EN FLG
IN OUT
GND
ERROR
FLAG OUTPUT
VOUT
2.5V
47µF
MIC39500
MIC39501
StrongARM is a trademark of Advanced RISC Machines, Ltd.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
June 1999
1 MIC39500/39501
1 page  
MIC39500/39501
Applications Information
The MIC39500/1 is a high-performance low-dropout voltage
regulator suitable for moderate to high-current voltage regu-
lator applications. Its 500mV dropout voltage at full load
makes it especially valuable in battery-powered systems and
as a high-efficiency noise filter in post-regulator applications.
Unlike older NPN-pass transistor designs, where the mini-
mum dropout voltage is limited by the base-to-emitter voltage
drop and collector-to-emitter saturation voltage, dropout per-
formance of the PNP output of these devices is limited only
by the low VCE saturation voltage.
A trade-off for the low dropout voltage is a varying base drive
requirement. Micrel’s Super βeta PNP™ process reduces
this drive requirement to only 2% to 5% of the load current.
The MIC39500/1 regulator is fully protected from damage
due to fault conditions. Current limiting is provided. This
limiting is linear; output current during overload conditions is
constant. Thermal shutdown disables the device when the
die temperature exceeds the maximum safe operating tem-
perature. Transient protection allows device (and load) sur-
vival even when the input voltage spikes above and below
nominal. The output structure of these regulators allows
voltages in excess of the desired output voltage to be applied
without reverse current flow.
VIN MIC39500-x.x
IN OUT
VOUT
GND
CIN COUT
Figure 1. Capacitor Requirements
Thermal Design
Linear regulators are simple to use. The most complicated
design parameters to consider are thermal characteristics.
Thermal design requires four application-specific param-
eters:
• Maximum ambient temperature (TA)
• Output Current (IOUT)
• Output Voltage (VOUT)
• Input Voltage (VIN)
• Ground Current (IGND)
Calculate the power dissipation of the regulator from these
numbers and the device parameters from this datasheet,
where the ground current is taken from data sheet.
PD = (VIN – VOUT) × IOUT + VIN × IGND
The heat sink thermal resistance is determined by:
( )θSA
=
TJ(max) − TA
PD
−
θJC + θCS
where:
TJ (max) ≤ 125°C and θCS is between 0° and 2°C/W.
Micrel
The heat sink may be significantly reduced in applications
where the minimum input voltage is known and is large
compared with the dropout voltage. Use a series input
resistor to drop excessive voltage and distribute the heat
between this resistor and the regulator. The low-dropout
properties of Micrel Super βeta PNP regulators allow signifi-
cant reductions in regulator power dissipation and the asso-
ciated heat sink without compromising performance. When
this technique is employed, a capacitor of at least 1µF is
needed directly between the input and regulator ground.
Refer to Application Note 9 for further details and examples
on thermal design and heat sink specification.
Output capacitor
The MIC39500/1 requires an output capacitor to maintain
stability and improve transient response. Proper capacitor
selection is important to ensure proper operation. The
MIC39500/1 output capacitor selection is dependent upon
the ESR (equivalent series resistance) of the output capacitor
to maintain stability. When the output capacitor is 47µF or
greater, the output capacitor should have less than 1Ω of
ESR. This will improve transient response as well as promote
stability. Ultra-low-ESR capacitors, such as ceramic chip
capacitors may promote instability. These very low ESR
levels may cause an oscillation and/or underdamped tran-
sient response. A low-ESR solid tantalum capacitor works
extremely well and provides good transient response and
stability over temperature. Aluminum electrolytics can also
be used, as long as the ESR of the capacitor is < 1Ω.
The value of the output capacitor can be increased without
limit. Higher capacitance values help to improve transient
response and ripple rejection and reduce output noise.
Input capacitor
An input capacitor of 1µF or greater is recommended when
the device is more than 4 inches away from the bulk ac supply
capacitance, or when the supply is a battery. Small surface-
mount ceramic chip capacitors can be used for bypassing.
Larger values will help to improve ripple rejection by bypass-
ing the input to the regulator, further improving the integrity of
the output voltage.
Transient Response
The MIC39500/1 has excellent transient response to varia-
tions in input voltage and load current. The device has been
designed to respond quickly to load current variations and
input voltage variations. Large output capacitors are not
required to obtain this performance. A standard 47µF output
capacitor, preferably tantalum, is all that is required. Larger
values improve performance even further.
3.3V to 2.5V Conversion
By virtue of its low-dropout voltage, this device does not
saturate into dropout as readily as similar NPN-based de-
signs. When converting from 3.3V to 2.5V, the NPN-based
regulators are already operating in dropout, with typical
dropout requirements of 1.2V or greater. To convert down to
2.5V without operating in dropout, NPN-based regulators
require an input voltage of 3.7V at the very least. The
MIC39500/1 regulator provides excellent performance with
June 1999
5 MIC39500/39501
5 Page | ||
| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet MIC39500-2.5BT.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| MIC39500-2.5BT | 5A Low-Voltage Low-Dropout Regulator Advance Information | Micrel Semiconductor |
| MIC39500-2.5BU | 5A Low-Voltage Low-Dropout Regulator Advance Information | Micrel Semiconductor |
| 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 |