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PDF SC2678 Data sheet ( Hoja de datos )
| Número de pieza | SC2678 | |
| Descripción | 5A 240KHZ 36V PWM Buck DC/DC Converter | |
| Fabricantes | CSM | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de SC2678 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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55AA24204K0HKz H35ZV B3u6cVk DPCWtoMDCBCuoncvkerDteCr /DC Converter
SC2678
General Description
Features
The SC2678 is a 240 KHz fixed frequency
monolithic step down switch mode regulator
with a built in internal Power MOSFET. It
achieves 5A continuous output current over a
wide input supply range with excellent load
and line regulation.
The device includes a voltage reference,
oscillation circuit, error amplifier, internal
PMOS and etc.
The PWM control circuit is able to adjust the
duty ratio linearly from 0 to 100%. An enable
function, an over current protection function
and a short circuit protection function are
built inside. An internal compensation block
is built in to minimize external component
count.
The SC2678 serves as ideal power supply
units for portable devices.
5A Constant Output Current
80mΩ RDSON Internal Power PMOSFET
Switch
Up to 95% Efficiency
Fixed 240KHz Frequency
Wide 3.6V to 35V Input Voltage Range
Output Adjustable from 1.222V to 30V
Built in Frequency Compensation
Built in Thermal Shutdown Function
Built in Current Limit Function
TO-263 Package is Available
The minimum dropout up to 0.3V
Applications
Portable DVD
LCD Monitor / TV
Battery Charger
ADSL Modem
Telecom / Networking Equipment
TO263-5L
Figure 1 Package Type of SC2678
TEL:0755-27668758/29469758
web:http://www.zgsemi.com www.086ic.cn
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1 page  
55AA24204K0HKz H35ZV B3u6cVk DPCWtoMDCBCuoncvkerDteCr /DC Converter
Typical Performance Characteristics
SC2678
Figure 4. Switching Frequency vs. Temperature
Figure 5. Vfb vs. Temperature
Figure 6. Icc vs. Temperature
Figure 7. Efficiency vs. Load (Vin=10V)
TEL:0755-27668758/29469758
web:http://www.zgsemi.com www.086ic.cn
5
5 Page 
55AA24204K0HKz H35ZV B3u6cVk DPCWtoMDCBCuoncvkerDteCr /DC Converter
SC2678
loop starts from the input capacitors, to the VIN
pin, to the VOUT pins, to the filter inductor, to the
output capacitor and load, and then returns to the
input capacitor through ground.
Current flows in the first loop when the high side
switch is on. The second loop starts from the
inductor, to the output capacitors and load, to the
GND pin of the SC2678, and to the VOUT pins of
the SC2678. Current flows in the second loop
when the low side diode is on.
In PCB layout, minimizing the two loops area
reduces the noise of this circuit and improves
efficiency. A ground plane is recommended to
connect input capacitor, output capacitor, and
GND pin of the SC2678.
In the SC2678 buck regulator circuit, the two
major power dissipating components are the
SC2678 and output inductor. The total power
dissipation of converter circuit can be measured
by input power minus output power.
Ptotal _loss = V IN × IIN – V O × IO
The power dissipation of inductor can be
approximately calculated by output current and
DCR of inductor.
Pinductor _loss= IO 2 × Rinductor × 1.1
The junction to ambient temperature can be got
from power dissipation in the SC2678 and thermal
impedance from junction to ambient.
T (jun-amb) =(Ptotalloss–Pinductorloss)× ΘJA
The maximum junction temperature of SC2678 is
145°C, which limits the maximum load current
capability. Please see the thermal de-rating
curves for the maximum load current of the
SC2678 under different ambient temperatures.
The thermal performance of the SC2678 is trongly
affected by the PCB layout. Extra care should be
taken by users during the design process to nsure
that the IC will operate under the recommended
environmental conditions.
Several layout tips are listed below for the best
electric and thermal performance.
1. Do not use thermal relief connection to the VIN
and the GND pin. Pour a maximized copper area
to the GND pin and the VIN pin to help thermal
dissipation.
2. Input capacitor should be connected to the VIN
pin and the GND pin as close as possible.
3. Make the current trace from VOUT pins to L to
the GND as short as possible.
4. Pour copper plane on all unused board area
and connect it to stable DC nodes, like VIN, GND,
or VOUT.
5. Keep sensitive signal traces such as trace
connecting FB pin away from the VOUT pins.
TEL:0755-27668758/29469758
11
web:http://www.zgsemi.com www.086ic.cn
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet SC2678.PDF ] | |
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