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PDF UC3848 Data sheet ( Hoja de datos )
| Número de pieza | UC3848 | |
| Descripción | HIGH PERFORMANCE CURRENT MODE CONTROLLERS | |
| Fabricantes | Unisonic Technologies | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de UC3848 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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UNISONIC TECHNOLOGIES CO., LTD
UC3848
LINEAR INTEGRATED CIRCUIT
HIGH PERFORMANCE
CURRENT MODE
CONTROLLERS
DESCRIPTION
The UTC UC3848 is designed to provide several special
enhancements to satisfy the needs: Power-Saving mode for low
standby power, Over Current Protection (OCP), Over Voltage
Protection (OVP), Over Load Protection (OLP), Over Temperature
Protection (OTP) etc protection features. IC will be shutdown when
either protection arise and can auto-restart. UVLO featuring typical
start-up current 20µA, and VCC(ON) 12.6V, VCC(OFF) 8.1 . Lower
typical operation current Icc 3.7mA at inactive output. The output
stage, suitable for driving N-Channel MOSFETs, can operate to duty
cycles approach 70%. The UC3848 are fully pin-to-pin compatible
with UC3842 except VREF-pin and NC-pin. VREF-pin’s application as
application circuits. Pin FB with an 4kΩ pull up resistor to internal
reference voltage. The UC3848 also have soft-start function avoiding
overshoot, and controlled driver output rise edge time tR for low EMI.
FEATURES
* Low startup and operation current
* 68kHz switching frequency
* Max duty cycle 70%
* Power-saving mode for low power
* Under voltage lockout with hysteresis
* Over temperature protection
* Overload protection
* Over voltage protection
* Leading edge blanking
* Soft start
ORDERING INFORMATION
Ordering Number
Normal
Lead Free Plating
UC3848-D08-T
UC3848L-D08-T
UC3848-S08-R
UC3848L-S08-R
UC3848-S08-T
UC3848L-S08-T
Package
DIP-8
SOP-8
SOP-8
*Pb-free plating product number: UC3848L
Packing
Tube
Tape Reel
Tube
www.unisonic.com.tw
Copyright © 2008 Unisonic Technologies Co., Ltd
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UC3848
LINEAR INTEGRATED CIRCUIT
FUNCTIONAL DESCRIPTION
The internal reference voltages and bias circuit work at VCC>12.6V, and shutdown at VCC< 8.1V.
(1) Soft-Start
When every IC power on, driver output duty cycle will be decided by voltage VSS on soft-start capacitor and VCS on
current sense resistor at beginning. After VSS reach 5.1V, the whole soft-start phase end, and driver duty cycle
depend on VFB and VCS. The relation among VSS, VFB and VOUT as followed FIG.3, here soft-start phase Tsoft-start
should more than VOUT start-up phase Tstart-up, otherwise, IC will enter false OLP protection state. Because after the
soft-start phase end, if VOUT remain in lower voltage, VFB more than 4.6V, then IC enter false OLP state.
Furthermore, soft-start phase should end before VCC reach VCC(MIN) during VCC power on. Otherwise, if soft-start
phase remain not end before VCC reach VCC(MIN) during VCC power on, IC will enter auto-restart phase and not set up
VOUT.
Finally soft-start also set OVP active phase. OVP active phase between VSS=0 and VSS=3.8V, OVP will not be
sensed after VSS reach 3.8V.The Soft-start phase TSS
6 ms
TSS = 12 ms
120 ms
(CSS=0.05uF)
(CSS=0.1uF)
(CSS=1uF)
FIG.3 Soft-start phase
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
5 of 12
QW-R103-033,C
5 Page 
UC3848
TYPICAL CHARACTERISTICS(Cont.)
LINEAR INTEGRATED CIRCUIT
Feedback Voltage During Loadjump From 10%
Up To 100% Load (VDCIN=120V)
120mV
3.86V
1.64kHz
850Hz
Ch1 max
6.00V
Ch1 min
460mV
Ch1 frequency
785.5Hz
Feedback Voltage During Loadjump From 10%
Up To 100% Load (VDCIN=350V)
60.0mV
3.30V
3.29kHz
1.70kHz
Ch1 max
5.90V
Ch1 min
40.0mV
Ch1 frequency
1.906kHz
Ch1 1.00V
M 400 s A Ch1
3.18V
Ch1 1.00V
M 200 s A Ch1
2.68V
Startup With Full Load Condition At VDCIN=120V,
Vc4 and Vout
12.3V
12.3V
VC4
VOUT
Ch1 max
5.04V
Ch1 min
1.32V
Ch1 frequency
-----Hz
Startup With Full Load Condition At VDCIN=350V,
Vc4 and Vout
12.3V
12.3V
VC4
VOUT
Ch1 max
5.04V
Ch1 min
-120mV
Ch1 frequency
-----Hz
Ch1 2.00V Ch2 5.00V M 10.0ms A Ch1
3.16V
Ch1 2.00V Ch2 5.00V M 10.0ms A Ch1
3.16V
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
11 of 12
QW-R103-033,C
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet UC3848.PDF ] | |
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