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PDF LM26420 Data sheet ( Hoja de datos )
| Número de pieza | LM26420 | |
| Descripción | High Frequency 2.0A Load - Step-Down DC-DC Regulator | |
| Fabricantes | National Semiconductor Corporation | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LM26420 (archivo pdf) en la parte inferior de esta página. Total 28 Páginas | ||
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LM26420
March 24, 2009
Dual 2.0A, High Frequency Synchronous Step-Down DC-
DC Regulator
www.daGtasehneeet4ru.acolmDescription
The LM26420 regulator is a monolithic, high frequency, dual
PWM step-down DC/DC converter in a 16 Pin LLP and a 20
Pin eTSSOP package. It provides all the active functions to
provide local DC/DC conversion with fast transient response
and accurate regulation in the smallest possible PCB area.
With a minimum of external components, the LM26420 is
easy to use. The ability to drive two 2.0A loads with an internal
75 mΩ PMOS top switch and an internal 50 mΩ NMOS bottom
switch using state-of-the-art 0.5 µm BiCMOS technology re-
sults in the best power density available. The world-class
control circuitry allows on-times as low as 30ns, thus sup-
porting exceptionally high frequency conversion over the en-
tire 3V to 5.5V input operating range down to the minimum
output voltage of 0.8V. Switching frequency is internally set
to 550 kHz or 2.2 MHz, allowing the use of extremely small
surface mount inductors and chip capacitors. Even though the
operating frequency is high, efficiencies up to 93% are easy
to achieve. External shutdown is included, featuring an ultra-
low stand-by current. The LM26420 utilizes current-mode
control and internal compensation to provide high-perfor-
mance regulation over a wide range of operating conditions.
Additional features include internal soft-start circuitry to re-
duce inrush current, pulse-by-pulse current limit, thermal
shutdown, power good indicators, precision enables, and out-
put over-voltage protection.
Features
■ Input voltage range of 3.0V to 5.5V
■ Output voltage range of 0.8V to 4.5V
■ 2.0A output current per output
■ High Switching Frequencies
2.2MHz (LM26420X)
0.55MHz (LM26420Y)
■ 75mΩ PMOS switch
■ 50mΩ NMOS switch
■ 0.8V, 1.5% Internal Voltage Reference
■ Internal soft-start
■ Independent power good for each output
■ Independent precision enable for each output
■ Current mode, PWM operation
■ Thermal Shutdown
■ Over voltage protection
■ Start-up into Pre-biased Output Loads
■ Outputs are 180° out of phase
Applications
■ Local 5V to Vcore Step-Down Converters
■ Core Power in HDDs
■ Set-Top Boxes
■ USB Powered Devices
■ DSL Modems
■ Powering Core and I/O voltages for FPGAs, CPLDs, and
ASICs
Typical Application Circuit
30069664
© 2009 National Semiconductor Corporation 300696
30069684
www.national.com
1 page  
Symbol
θJA
θJC
TSD
Parameter
Junction to Ambient
0 LFPM Air Flow (Note 4)
Junction to Case (Note 4)
Thermal Shutdown Temperature
Conditions
LLP-16
eTSSOP-20
LLP-16
eTSSOP-20
Min Typ Max Units
40
35
°C/W
6.8
3.9
165 °C
Note 1: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Operating Range indicates conditions for which the device is
wwinwte.nddaetdatsohbeeefut4nuct.icoonaml, but does not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: Thermal shutdown will occur if the junction temperature exceeds the maximum junction temperature of the device.
Note 3: The human body model is a 100pF capacitor discharged through a 1.5 kΩ resistor into each pin. Test method is per JESD-22-A114.
Note 4: Applies to a 4-layer standard JEDEC thermal test board or 4LJEDEC is 4"x3" in size. The board has 2 imbedded copper layers which cover roughly the
same size as the board. The copper thickness for the four layers, starting from the top one, is 2 oz./1oz./1oz./2 oz. For LLP, thermal vias are placed between the
die attach pad in the 1st. copper layer and 2nd. copper layer.
5 www.national.com
5 Page 
Simplified Block Diagram Per Buck
www.datasheet4u.com
FIGURE 1.
11
30069604
www.national.com
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet LM26420.PDF ] | |
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