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Details, datasheet, quote on part number:UTCUC3844/45
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| Part: | UTCUC3844/45 |
| Category: | Power Management => Power Supply Controllers |
| Description: | Description = PWM Controllers With Low Start-up Current ;; Package = DIP-8, SOP-8 ;; |
| Company: | Unisonic Technologies |
| Datasheet: | Download UTCUC3844/45 datasheet File size : 149 kB |
| Request For quote: | Find where to buy UTCUC3844/45
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Datasheet text preview:
UTC UC3844/45 LINEAR INTEGRATED CIRCUIT
HIGH PERFORMANCE CURRENT MODE CONTROLLERS
DESCRIPTION
The UTC UC3844 and UTC UC3845 are high performance fixed frequency current mode controllers. They are specifically designed for Off-Line and dc-to-dc converter applications offering the designer a cost effective solution with minimal external components. The UTC UC3844 has UVLO thresholds of 16V(on) and 10V(off), ideally suited for off-line converters. The UTC UC3845 is tailored for lower voltage applications having UVLO thresholds of 8.5V(on) and 7.6V(off).
SOP-8
DIP-8
FEATURES
*Current Mode Operation to 500 kHz Output Switching Frequency *Output Deadtime Adjustable from 50% to 70% *Automatic Feed Forward Compensation *Latching PWM for Cycle-By-Cycle Current Limiting *Internally Trimmed Reference with Under voltage Lockout *High Current Totem Pole Output *Input Undervoltage Lockout with Hysteresis *Low Startup and Operating Current
PIN CONFIGURATION
Compensation
1
8
Vref
Voltage Feedback
2
7
Vcc
Current Sense
3
6
Output
RT/CT
4
5
Gnd
UTC
UNISONIC TECHNOLOGIES CO., LTD.
1
QW-R103-010,B
UTC UC3844/45 LINEAR INTEGRATED CIRCUIT
PIN DESCRIPTION
PIN 1 2 3 4 5 6 7 8 SYMBOL Voltage Feedback DESCRIPTION This is the inverting input of the Error Amplifier. It is normally connected to the switching power supply output through a resistor divider. information to terminate the output switch conduction. RT/CT Gnd Output Vcc Vref The Oscillator frequency and maximum output duty cycle are programmed by connecting resistor RT to Vref and capacitor CT to ground. Operation to 1.0 MHz is possible. This pin is combined control circuitry and power ground. This output directly drives the gate of a power MOSFET. Peak currents up to 1.0A are sourced and sunk by this pin. The output switches at one-half the oscillator frequency. This pin is the positive supply of the control IC. This is the reference output. It provides charging current for capacitor CT though resistor RT. Compensation This pin is Error amplifier output and is made available for loop compensation.
Current Sense A voltage proportional to inductor current is connected to this input. The PWM uses this
BLOCK DIAGRAM
UTC
UNISONIC TECHNOLOGIES CO., LTD.
2
QW-R103-010,B
UTC UC3844/45 LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS (Ta=25°C )
PARAMETER
Total Power Supply and Zener Current Output Current, Source or Sink (Note 1) Output Energy (Capacitive Load per cycle) Current Sense and Voltage feedback Inputs Error Amp Output Sink Current Power Dissipation and thermal Characteristics SOP-8 Maximum Power Dissipation @ TA=25°C Thermal Resistance Junction-to-Air DIP-8 Maximum Power Dissipation @ TA=25°C Thermal Resistance Junction-to-Air Operating Junction Temperature Operating Ambient Temperature Storage Temperature Range
SYMBOL
(Icc+Iz) Io W Vin Io PD RJA PD RJA Tj TA Tstg
VALUE
30 1.0 5.0 -0.3 ~ +5.5 10 862 145 1250 100 +150 0 ~ 70 -65 ~ +150
UNIT
mA A µJ V mA mW °C/W mW °C/W °C °C °C
ELECTRICAL CHARACTERISTICS (Ta=25°C)
(Vcc=15V,[Note 2], RT=10k,CT=3.3nF,TA=Tlow to Thigh [Note 3], unless otherwise specified)
PARAMETER
SYMBOL
Vref Regline Regload Ts Vref Vn S ISC fosc
TEST CONDITIONS
Io=1.0mA,Tj=25 C Vcc=12V to 25V Io=1.0mA to 20mA
MIN
4.9 4.82 -30
TYP.
5.0 2.0 3.0 0.2
MAX
5.1 20 25 5.18 -180
UNIT
V mV mV mV/°C V µV mV mA kHz
REFERENCE SECTION
Reference Output Voltage Line Regulation Load Regulation Temperature Stability Total Output Variation over Line, Load, Temperature Output Noise Voltage Long Term Stability Output Short Circuit Current
f=10Hz to kHz, Tj=25°C TA=125°C for 1000 Hours
50 5.0 -85
OSCILLATOR SECTION
Frequency Tj=25°C TA=Tlow to Thigh Vcc=12V to 25V TA=Tlow to Thigh Vosc=2.0V,Tj=25°C Vo=2.5V VFB=2.7V Vo=2.0V to 4.0V Tj=25°C Vcc=12V to 25V Vo=1.1V, VFB=2.7V Vo=5.0V, VFB=2.3V 47 46 2.42 65 0.7 60 2.0 -0.5 52 0.2 5.0 1.6 10.8 2.50 -0.1 90 1.0 70 12 -1.0 57 60 1.0 2.58 -2.0 -
Frequency Change with Voltage fosc/V Frequency Change with Temperature fosc/T Oscillator Voltage Swing Vosc Discharge Current Idischg
% % V mA V µA dB MHz dB mA
ERROR AMPLIFIER SECTION
Voltage Feedback Input Input Bias Current Open Loop Voltage Gain Unity Gain Bandwidth Power Supply Rejection Ratio Output Current Sink Source VFB IIB AVOL BW PSRR Isink Isoure
UTC
UNISONIC TECHNOLOGIES CO., LTD.
3
QW-R103-010,B
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