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PDF EM5305 Data sheet ( Hoja de datos )
| Número de pieza | EM5305 | |
| Descripción | 12V Synchronous Buck controller | |
| Fabricantes | Excelliance MOS | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de EM5305 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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12V Synchronous Buck controller
General Description
The EM5305 series are compact synchronous
-rectified buck controllers specifically designed to
operate from 5V or 12V supply voltage. The output
voltage is tightly regulated to the external
reference voltage from 0.4V to 3.0V. These devices
operate at fixed 300 kHz frequency and provide an
optimal level of integration to redwuce size and
cost of the power supply.
The controllers integrate internal MOSFET drivers
that support 12V+12V bootstrapped voltage for
high efficiency power conversion. The bootstrap
diode is built-in to simplify the circuit design and
minimize external part count.
Other features include internal soft-start,
under-voltage protection, over-voltage protection,
over-current protection and shutdown function.
With aforementioned functions, these parts
provide customers a compact, high efficiency,
well-protected and cost-effective solutions. These
parts are available in DFN3x3-10L package.
EM5305
Features
Tracking mode
300 kHz fixed frequency operation.
Voltage mode PWM control with external
compensation (GM)
Internal soft start
Integrated bootstrap diode
Low side MOS OC protection
OUT UV protection
OUT OV protection
Power Good Indicator
0.8V Reference Output
Pin Configuration
Ordering Information
Part Number
EM5305VT
Package
DFN3x3-10L
Lead-Free
Remark
Applications
Power Supplies for Microprocessors or
Subsystem Power Supplies
Cable Modems, Set Top Boxes, and xDSL
Modems
5V or 12V Input DC-DC Regulators
Graphics Cards
Typical Application Circuit
+5V to +12V
Disable
Enable
OFS 9
CS RS
REFOUT 10
COMP/
SD# 7
FB 6
5 VCC
1 BOOT
GND
UGATE
2
PHASE
3
LGATE
4
POK
8
VIN
+3.3V +5V +12V
Option
1. 1/(2×π×RS×CS)≦30KHz
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1 page  
EM5305
Internal Oscillator
Free Running Frequency
Ramp Amplitude
fOSC
△VOSC
270 300 330 kHz
1.5 Vp-p
Max. Duty Cycle
Error Amplifier
DMAX
80 85 90 %
Trans-conductance
Gm
700 uA/V
Max. Comp Source Current
100 200
uA
Max. Comp Sink Current
100 200
uA
PWM Controller Gate Drivers
Upper Gate Sourcing Current
Upper Gate RDS(ON) Sinking
Lower Gate Sourcing Current
Lower Gate RDS(ON) Sinking
IUG_SRC
RUG_SNK
ILG_SRC
RLG_SNK
VBOOT - VPHASE = 12V,
VBOOT - VUGATE = 6V
VBOOT - VPHASE = 12V,
VUGATE – VPHASE = 0.1V
VCC – VLGATE = 6V
VLGATE = 0.1V
1.2 A
3Ω
1.2 A
1.8 Ω
PHASE Falling to LGATE Rising
Delay
LGATE Falling to UGATE Rising
Delay
Reference Voltage
VCC = 12V; (VUGATE - VPHASE)< 1.2V
to VLGATE > 1.2V
VCC = 12V; VLGATE < 1.2V to
(VUGATE - VPHASE) > 1.2V
30 90 ns
30 90 ns
Feedback Voltage
Reference Output
Reference Output Source/Sink
Protection section
VFB
VREFOUT
IREFOUT
VOFS= 0.8V
0.792 0.8 0.808 V
0.792 0.8 0.808 V
5 mA
FB Under Voltage Protection
UVP delay time
VFB_UVP FB falling
50 60 70
7.5 10
%
us
FB Over Voltage Protection
OVP delay time
VFB_OVP FB rising
120 130 140 %
7.5 10 us
LGATE OC Setting Current
Built in Max. OCP Threshold
IOCSET
8.5 10 11.5 uA
-630
mV
Soft-Start Interval
COMP Shutdown Threshold
POK Threshold
POK Delay
TSS
VCOMP/
SD#
VPOK
1 2 3 ms
0.4 V
88 90 92 %
1 2 3 ms
Power Good Leakage Current
1 uA
Temperature Shutdown
TSD
140 ℃
Temperature Shutdown
Hysteresis
TSD_Hys
40 ℃
Note 1.
Note 2.
Note 3.
Note 4.
Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for
stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may remain possibility to affect device reliability.
θJA PSOP-8 packages is 52°C /W on JEDEC 51-7 (4 layers,2S2P) thermal test board with 50mm2 copper area.
Devices are ESD sensitive. Handling precaution is recommended.
The device is not guaranteed to function outside its operating conditions.
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5 Page 
Input Capacitor Selection
Use a mix of input bypass capacitors to control the
voltage overshoot across the MOSFET. Use small
ceramic capacitors for high frequency decoupling
and bulk capacitors to supply the current needed
each time the upper MOSFET turn on. Place the
small ceramic capacitors physically close to the
MOSFETs and between the drain of the upper
MOSFET and the source of the lower MOSFET. The
important parameters of the input capacitor are
the voltage rating and the RMS current rating.
The capacitor voltage rating should be at least 1.25
times greater than the maximum input voltage and
a voltage rating of 1.5 times is a conservative
guideline. The RMS current rating requirement can
be expressed as the following equation:
IRMS = IOUT D(1 - D)
For a through hole design, several electrolytic
capacitors may be needed. For surface mount
designs, solid tantalum capacitors can also be used
but caution must be exercised with regard to the
capacitor surge current rating. These capacitors
must be capable of handling the surge current at
power-up. Some capacitor series available from
reputable manufacturers are surge current tested.
EM5305
Power MOSFET Selection
The EM5305 requires two N-Channel power
MOSFETs. These should be selected based upon
on-resistance, breakdown voltage, gate supply
requirement, and thermal management
requirements.
In high current applications, the MOSFET power
dissipation, package selection and heat sink are the
dominate design factor. The power dissipation
includes two loss components: conduction loss and
switching loss. The conduction losses are the
largest component of power dissipation for both
the upper and lower MOSFETs. These losses are
distributed between the two MOSFETs according
to duty factor.
The power dissipations in the two MOSFETs are
approximately the following equation:
PDUPPER
=
I2
OUT
* RDS(ON)
*D
+
0.5 *IOUT
* VIN
* FSW
* tSW
PDLOWER
=
I2
OUT
* RDS(ON)
* (1 - D)
Where D is the duty cycle, tSW is the combined
switch ON and OFF time.
2013/7/11
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11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet EM5305.PDF ] | |
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