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Part: UC2844AQD
Category:
Power Management
-> PWM Power Supply
-> Current Mode
Description: ti UC2844A, Current Mode PWM Controller
Company: Texas Instruments, Inc.
Datasheet: Download UC2844AQD datasheet File size : 216 kB
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Datasheet text preview:
application INFO available
UC1842A/3A/4A/5A UC2842A/3A/4A/5A UC3842A/3A/4A/5A
Current Mode PWM Controller
FEATURES
· · · · · · · · · · · · Optimized for Off-line and DC to DC Converters Low Start Up Current (<0.5mA) Trimmed Oscillator Discharge Current Automatic Feed Forward Compensation Pulse-by-Pulse Current Limiting Enhanced Load Response Characteristics Under-Voltage Lockout With Hysteresis Double Pulse Suppression
Part # UVLO On 16.0V 8.5V 16.0V 8.5V UVLO Off 10.0V 7.9V 10.0V 7.9V Maximum Duty Cycle <100% <100% <50% <50%
DESCRIPTION
The UC1842A/3A/4A/5A family of control ICs is a pin for pin compatible improved version of the UC3842/3/4/5 family. Providing the necessar y features to control current mode switched mode power supplies, this family has the following improved features. Star t up current is guaranteed to be less than 0.5mA. Oscillator discharge is trimmed to 8.3mA. During under voltage lockout, the output stage can sink at least 10mA at less than 1.2V for VCC over 5V. The difference between members of this family are shown in the table below.
High Current Totem Pole Output
UC1842A
Internally Trimmed Bandgap Reference 500kHz Operation Low RO Error Amp
UC1843A UC1844A UC1845A
BLOCK DIAGRAM
Note 1: A/B A = DIL-8 Pin Number. B = SO-14 Pin Number. Note 2: Toggle flip flop used only in 1844A and 1845A.
SLUS224A - SEPTEMBER 1994 - REVISED APRIL 2002
CONNECTION DIAGRAMS ABSOLUTE MAXIMUM RATINGS (Note 1)
Supply Voltage (Low Impedance Source) . . . . . . . . . . . . . . 30V Supply Voltage (ICC mA) . . . . . . . . . . . . . . . . . . . . Self Limiting Output Current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 1A Output Energy (Capacitive Load). . . . . . . . . . . . . . . . . . . . . 5µ J Analog Inputs (Pins 2, 3). . . . . . . . . . . . . . . . . . . -0.3V to +6.3V Error Amp Output Sink Current . . . . . . . . . . . . . . . . . . . . 10mA Power Dissipation at TA 25°C (DIL-8) . . . . . . . . . . . . . . . . 1W Storage Temperature Range . . . . . . . . . . . . . . -65°C to +150°C Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . 300°C Note 1. All voltages are with respect to Ground, Pin 5. Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages. Pin numbers refer to DIL package only.
UC1842A/3A/4A/5A UC2842A/3A/4A/5A UC3842A/3A/4A/5A
PLCC-20, LCC-20 (TOP VIEW) Q, L Packages
PACKAGE PIN FUNCTION FUNCTION PIN N/C 1 Comp 2 N/C 3-4 VFB 5 N/C 6 ISENSE 7 N/C 8-9 RT/CT 10 N/C 11 Pwr Gnd 12 Gnd 13 N/C 14 Output 15 N/C 16 VC 17 VCC 18 N/C 19 VREF 20
SOIC-14 (TOP VIEW) D Package
DIL-8, SOIC-8 (TOP VIEW) J or N, D8 Package
SOIC-WIDE16 (TOP VIEW) DW Package
N/C N/C COMP VFB ISENSE RT/CT N/C N/C 1 2 3 4 5 6 7 8 16 N/C 15 VREF 14 VCC 13 VCC 12 OUTPUT 11 GND 10 PWRGND 9 N/C
2
UC1842A/3A/4A/5A UC2842A/3A/4A/5A UC3842A/3A/4A/5A ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for 55°C TA 125°C for the UC184xA; 40°C TA 125°C for the UC284xAQ; 40°C TA 85°C for the UC284xA; 0 TA 70°C for the UC384xA; VCC = 15V (Note 5); RT = 10k; CT = 3.3nF; TA = TJ; Pin numbers refer to DIL-8.
PARAMETER Reference Section Output Voltage Line Regulation Load Regulation Temp. Stability Total Output Variation Output Noise Voltage Long Term Stability Output Short Circuit Oscillator Section Initial Accuracy Voltage Stability Temp. Stability Amplitude Discharge Current Error Amp Section Input Voltage Input Bias Current AVOL Unity Gain Bandwidth PSRR Output Sink Current Output Source Current VOUT High VOUT Low Current Sense Section Gain Maximum Input Signal PSRR Input Bias Current Delay to Output Output Section Output Low Level Output High Level Rise Time Fall Time UVLO Saturation TEST CONDITIONS UC184xA\UC284xA MIN. TYP. MAX. 4.95 5.00 6 6 0.2 5.05 20 25 0.4 5.1 MIN. 4.90 UC384xA UNITS TYP. MAX. 5.00 6 6 0.2 5.10 20 25 0.4 5.18 V mV mV mV/°C V µV mV mA kHz % % V mA mA V µA dB MHz dB mA mA V V V/V V dB µA ns V V V V ns ns V
TJ = 25°C, IO = 1mA 12 VIN 25V 1 IO 20mA (Note 2, Note 7) Line, Load, Temp. 10Hz f 10kHz TJ = 25°C (Note 2) TA = 125°C, 1000Hrs. (Note 2)
4.9 50 5 -100 52 0.2 5 1.7 8.3
4.82 50 5 -100 52 0.2 5 1.7 8.3
-30 TJ = 25°C (Note 6) 12 VCC 25V TMIN TA TMAX (Note 2) VPIN 4 peak to peak (Note 2) TJ = 25°C, VPIN 4 = 2V (Note 8) VPIN 4 = 2V (Note 8) VPIN 1 = 2.5V 2 VO 4V TJ = 25°C (Note 2) 12 VCC 25V VPIN 2 = 2.7V, VPIN 1 = 1.1V VPIN 2 = 2.3V, VPIN 1 = 5V VPIN 2 = 2.3V, RL = 15k to ground VPIN 2 = 2.7V, RL = 15k to Pin 8 (Note 3, Note 4) VPIN 1 = 5V (Note 3) 12 VCC 25V (Note 3) VPIN 3 = 0 to 2V (Note 2) ISINK = 20mA ISINK = 200mA ISOURCE = 20mA ISOURCE = 200mA TJ = 25°C, CL = 1nF (Note 2) TJ = 25°C, CL = 1nF (Note 2) VCC = 5V, ISINK = 10mA 47
25 -180 57 1
-30 47
25 -180 57 1
7.8 7.5 2.45 65 0.7 60 2 -0.5 5
8.8 8.8 2.55 -1
7.8 7.6 2.42 65 0.7 60 2 -0.5 5
8.8 8.8 2.58 -2
2.50 -0.3 90 1 70 6 -0.8 6 0.7 3 1 70 -2 150 0.1 15 13.5 13.5 50 50 0.7
1.1 3.15 1.1 -10 300 0.4 2.2 13 12 150 150 1.2 2.85 0.9
2.50 -0.3 90 1 70 6 -0.8 6 0.7 3 1 70 -2 150 0.1 15 13.5 13.5 50 50 0.7
1.1 3.15 1.1 -10 300 0.4 2.2
2.85 0.9
13 12
150 150 1.2
3
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