UCC3813-2

application INFO available UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5 Low Power Economy BiCMOS Current Mode PWM FEATURES • 100mA Typical Starting Supply Current • 500mA Typical Operating Supply Current • Operation to 1MHz • Internal Soft Start • Internal Fault Soft Start • Internal Leading-Edge Blanking of the Current Sense Signal • 1 Amp Totem-Pole Output • 70ns Typical Response from Current-Sense to Gate Drive Output • 1.5% Tolerance Voltage Reference • Same Pinout as UCC3802, UC3842, and UC3842A DESCRIPTION The UCC3813-0/-1/-2/-3/-4/-5 family of high-speed, low-power integrated circuits contain all of the control and drive components required for off-line and DC-to-DC fixed frequency current-mode switching power supplies with minimal parts count. These devices have the same pin configuration as the UC3842/3/4/5 family, and also offer the added features of internal full-cycle soft start and internal leading-edge blanking of the current-sense input. The UCC3813-0/-1/-2/-3/-4/-5 family offers a variety of package options, temperature range options, choice of maximum duty cycle, and choice of critical voltage levels. Lower reference parts such as the UCC3813-3 and UCC3813-5 fit best into battery operated systems, while the higher reference and the higher UVLO hysteresis of the UCC3813-2 and UCC3813-4 make these ideal choices for use in off-line power supplies. The UCC2813-x series is specified for operation from –40°C to +85°C and the UCC3813-x series is specified for operation from 0°C to +70°C. ORDERING INFORMATION Part Number UCCx813-0 UCCx813-1 UCCx813-2 UCCx813-3 UCCx813-4 UCCx813-5 Maximum Duty Cycle 100% 50% 100% 100% 50% 50% Reference Voltage 5V 5V 5V 4V 5V 4V Turn-On Threshold 7.2V 9.4V 12.5V 4.1V 12.5V 4.1V Turn-Off Threshold 6.9V 7.4V 8.3V 3.6V 8.3V 3.6V BLOCK DIAGRAM UDG-96134 SLUS161A - APRIL 1999 - REVISED JANUARY 2005 UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5 ABSOLUTE MAXIMUM RATINGS (Note 1) VCC Voltage (Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0V VCC Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.0mA OUT Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±1.0A OUT Energy (Capacitive Load) . . . . . . . . . . . . . . . . . . . 20.0mJ Analog Inputs (FB, CS) . . . . . . . . . . . . . . . . . . . . –0.3V to 6.3V Power Dissipation at TA < +25°C (N Package). . . . . . . . . 1.0W Power Dissipation at TA < +25°C (D Package). . . . . . . . 0.65W Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C Lead Temperature (Soldering, 10 Seconds). . . . . . . . . +300°C Note 1: All voltages are with respect to GND. All currents are positive into the specified terminal. Consult Unitrode Integrated Circuits databook for information regarding thermal specifications and limitations of packages. Note 2: In normal operation VCC is powered through a current limiting resistor. Absolute maximum of 12V applies when VCC is driven from a low impedance source such that ICC does not exceed 30mA. The resistor should be sized so that the VCC voltage under operating conditions is below 12V but above the turn off threshold. TEMPERATURE RANGE –40°C TO +85°C 0°C TO +70°C PACKAGES N, D, PW N, D, PW CONNECTION DIAGRAMS DIL-8 or SOIC-8 (TOP VIEW) N or D PACKAGE COMP FB CS RC 1 2 3 4 8 7 6 5 REF VCC OUT GND TSSOP-8 (TOP VIEW) PW PACKAGE 1 COMP FB CS RC REF VCC OUT GND 8 7 6 5 UCC2813 UCC3813 2 3 4 ORDERING INFORMATION UCC 813 – PRODUCT OPTION PACKAGE TEMPERATURE RANGE ELECTRICAL CHARACTERISTICSUnless otherwise stated, these specifications apply for –40°C £ TA £ +85°C for UCC2813-x; 0°C £ TA £ +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND; 0.1mF capacitor from VCC to GND; 0.1mF capacitor from VREF to GND. TA = TJ. PARAMETER Reference Section Output Voltage Load Regulation Total Variation Output Noise Voltage Long Term Stability Output Short Circuit Oscillator Section Oscillator Frequency Temperature Stability Amplitude Peak-to-Peak Oscillator Peak Voltage UCCx813-0/-1/-2/-4 (Note 4) UCCx813-5 (Note 4) (Note 9) 2.25 40 26 46 31 2.5 2.40 2.45 2.55 52 36 kHz kHz % V V TJ = +25°C, I = 0.2mA, UCCx813-0/-1/-2/-4 TJ = +25°C, I = 0.2mA, UCCx813-5 0.2mA < I < 5mA UCCx813 -0-1/-2/-4 (Note 7) UCCx813-5 (Note 7) 10Hz £ f £ 10kHz, TJ = +25°C (Note 9) TA = +125°C, 1000 Hours (Note 9) –5 4.84 3.84 4.925 3.94 5.00 4.00 10 5.00 4.00 70 5 –35 5.075 4.06 30 5.10 4.08 V V mV V V mV mV mA TEST CONDITIONS MIN UCC2813-x UCC3813-x TYP MAX UNITS 2 UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5 ELECTRICAL CHARACTERISTICSUnless otherwise stated, these specifications apply for –40°C £ TA £ +85°C for UCC2813-x; 0°C £ TA £ +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND; 0.1mF capacitor from VCC to GND; 0.1mF capacitor from VREF to GND. TA = TJ. PARAMETER Error Amplifier Section Input Voltage Input Bias Current Open Loop Voltage Gain COMP Sink Current COMP Source Current Gain Bandwidth Product PWM Section Maximum Duty Cycle Minimum Duty Cycle Current Sense Section Gain Maximum Input Signal Input Bias Current CS Blank Time Over-Current Threshold COMP to CS Offset Output Section OUT Low Level I = 20mA, all parts I = 200mA, all parts I = 50mA, VCC = 5V, UCCx813-3/-5 I = 20mA, VCC = 0V, all parts OUT High VSAT (VCC-OUT) Rise Time Fall Time Undervoltage Lockout Section Start Threshold (Note 8) UCCx813-0 UCCx813-1 UCCx813-2/-4 UCCx813-3/-5 Stop Threshold (Note 8) UCC1813-0 UCC1813-1 UCCx813-2/-4 UCCx813-3/-5 Start to Stop Hysteresis UCCx813-0 UCCx813-1 UCCx813-2/-4 UCCx813-3/-5 6.6 8.6 11.5 3.7 6.3 6.8 7.6 3.2 0.12 1.6 3.5 0.2 7.2 9.4 12.5 4.1 6.9 7.4 8.3 3.6 0.3 2 4.2 0.5 7.8 10.2 13.5 4.5 7.5 8.0 9.0 4.0 0.48 2.4 5.1 0.8 V V V V V V V V V V V V I = –20mA, all parts I = –200mA, all parts I = –50mA,VCC = 5V, UCCx813-3/-5 CL = 1nF CL = 1nF 0.1 0.35 0.15 0.7 0.15 1.0 0.4 41 44 0.4 0.90 0.40 1.2 0.40 1.9 0.9 70 75 V V V V V V V ns ns CS = 0V (Note 5) COMP = 5V (Note 6) 1.10 0.9 1.65 1.0 100 1.55 0.90 1.80 1.1 200 150 1.70 1.35 V/V V nA ns V V UCCx813-0/-2/-3 UCCx813-1/-4/-5 COMP = 0V 97 48 99 49 100 50 0 % % % FB = 2.7V, COMP = 1.1V FB = 1.8V, COMP = REF – 1.2V (Note 9) COMP = 2.5V; UCCx813-0/-1/-2/-4 COMP = 2.0V; UCCx813-3/-5 2.42 1.92 2.50 2.0 80 2.5 –0.5 2 –0.8 2.56 2.05 2 V V mA dB mA mA MHz TEST CONDITIONS MIN UCC2813-x UCC3813-x TYP MAX UNITS –2 60 0.4 –0.2 –200 50 1.32 0.45 3 UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5 ELECTRICAL CHARACTERISTICSUnless otherwise stated, these specifications apply for –40°C £ TA £ +85°C for UCC2813-x; 0°C £ TA £ +70°C for UCC3813-x; VCC = 10V (Note 3); RT = 100k from REF to RC; CT=330pF from RC to GND; 0.1mF capacitor from VCC to GND; 0.1mF capacitor from VREF to GND. TA = TJ. PARAMETER Soft Start Section COMP Rise Time Overall Section Start-up Current Operating Supply Current VCC Internal Zener Voltage VCC Internal Zener Voltage Minus Start Threshold Voltage VCC < Start Threshold FB = 0V, CS = 0V, RC = 0V ICC = 10mA (Note 8) UCCx813-2/-4 12 0.5 0.1 0.5 13.5 1.0 0.23 1.2 15 mA mA V V FB = 1.8V, Rise from 0.5V to REF–1V 4 ms TEST CONDITIONS MIN UCC2813-x UCC3813-x TYP MAX UNITS Note 3: Adjust VCC above the start threshold before setting at 10V. Note 4: Oscillator frequency for the UCCx813-0, UCCx813-2 and UCCx813-3 is the output frequency. Oscillator frequency for the UCCx813-1, UCCx813-4 and UCCx813-5 is twice the output frequency. D VCOMP Note 5: Gain is defined by: A = 0 £ VCS £ 0.8V . D VCS Note 6: Parameter measured at trip point of latch with Pin 2 at 0V. Note 7: Total Variation includes temperature stability and load regulation. Note 8: Start Threshold, Stop Threshold and Zener Shunt Thresholds track one another. Note 9: Ensured by design. Not 100% tested in production. PIN DESCRIPTIONS COMP: COMP is the output of the error amplifier and the input of the PWM comparator. Unlike other devices, the error amplifier in the UCC3813 family is a true, low output-impedance, 2MHz operational amplifier. As such, the COMP terminal can both source and sink current. However, the error amplifier is internally current limited, so that you can command zero duty cycle by externally forcing COMP to GND. The UCC3813 family features built-in full cycle Soft Start. Soft Start is implemented as a clamp on the maximum COMP voltage. FB: FB is the inverting input of the error amplifier. For best stability, keep FB lead length as short as possible and FB stray capacitance as small as possible. CS: CS is the input to the current sense comparators. The UCC3813 family has two different current sense comparators: the PWM comparator and an over-current comparator. The UCC3813 family contains digital current sense filtering, which disconnects the CS terminal from the current 4 sense comparator during the 100ns interval immediately following the rising edge of the OUT pin. This digital filtering, also called leading-edge blanking, means that in most applications, no analog filtering (RC filter) is required on CS. Compared to an external RC filter technique, the leading-edge blanking provides a smaller effective CS to OUT propagation delay. Note, however, that the minimum non-zero On-Time of the OUT signal is directly affected by the leading-edge-blanking and the CS to OUT propagation delay. The over-current comparator is only intended for fault sensing, and exceeding the over-current threshold will cause a soft start cycle. RC: RC is the oscillator timing pin. For fixed frequency operation, set timing capacitor charging current by connecting a resistor from REF to RC. Set frequency by connecting a timing capacitor from RC to GND. For best performance, keep the timing capacitor lead to GND as short and direct as possible. If possible, use separate ground traces for the timing capacitor and all other functions. UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5 PIN DESCRIPTIONS (cont.) The frequency of oscillation can be estimated with the following equations: UCCx813-0/-1/-2/-4: F = 1.5 R ·C 1.0 R ·C low, total supply current will be higher, depending on OUT current. Total VCC current is the sum of quiescent VCC current and the average OUT current. Knowing the operating frequency and the MOSFET gate charge (Qg), average OUT current can be calculated from: I OUT = Qg · F . To prevent noise problems, bypass VCC to GND with a 0.1 mF ceramic capacitor in parallel as close to the VCC pin as possible. An electrolytic capacitor may also be used in addition to the ceramic capacitor. REF: REF is the voltage reference for the error amplifier and also for many other functions on the IC. REF is also used as the logic power supply for high speed switching logic on the IC. When VCC is greater than 1V and less than the UVLO threshold, REF is pulled to ground through a 5kW resistor. This means that REF can be used as a logic output indicating power system status. It is important for reference stability that REF is bypassed to GND with a ceramic capacitor as close to the pin as possible. An electrolytic capacitor may also be used in addition to the ceramic capacitor. A minimum of 0.1mF ceramic is required. Additional REF bypassing is required for external loads greater than 2.5mA on the reference. To prevent noise problems with high speed switching transients, bypass REF to ground with a ceramic capacitor very close to the IC package. UCCx813-3, UCCx813-5: F = where frequency is in Hz, resistance is in W, and capacitance is in farads. The recommended range of timing resistors is between 10k and 200k and timing capacitor is 100pF to 1000pF. Never use a timing resistor less than 10k. GND: GND is reference ground and power ground for all functions on this part. OUT: OUT is the output of a high-current power driver capable of driving the gate of a power MOSFET with peak currents exceeding ±750mA. OUT is actively held low when VCC is below the UVLO threshold. The high-current power driver consists of FET output devices, which can switch all of the way to GND and all of the way to VCC. The output stage also provides a very low impedance to overshoot and undershoot. This means that in many cases, external schottky clamp diodes are not required. VCC: VCC is the power input connection for this device. In normal operation VCC is powered through a current limiting resistor. Although quiescent VCC current is very APPLICATION INFORMATION UDG-96139 The UCC3813-0/-1/-2/-3/-4/-5 oscillator generates a sawtooth waveform on RC. The rise time is set by the time constant of RT and CT. The fall time is set by CT and an internal transistor on-resistance of approximately 125W. During the fall time, the output is off and the maximum duty cycle is reduced below 50% or 100% depending on the part number. Larger timing capacitors increase the discharge time and reduce the maximum duty cycle and frequency. Figure 1. Oscillator. 5 UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5 APPLICATION INFORMATION (cont.) 4.00 3.98 3.96 3.94 VREF (V) 3.92 3.90 3.88 3.86 3.84 3.82 4 4.2 4.4 4.6 4.8 5 5.2 VCC (V) 5.4 5.6 5.8 6 Figure 2. Error amplifier gain/phase response. 1000 Figure 5. UCC3813-3/-5 VREF vs. VCC; ILOAD = 0.5mA. 1000 Oscillator Freq. (kHz) 10 100 0p F F Oscillator Freq. (kHz) 100 10 20 33 20 33 0p 0p F 0p F 0p F 0p F 1n F 1n 10 10 100 RT (k ) 1000 10 10 F 100 RT (k ) 1000 Figure 3. UCC3813-0/-1/-2/-4 oscillator frequency vs. RT and CT. 100 99.5 Figure 6. UCC3813-3/-5 oscillator frequency vs. RT and CT. 50 49.5 Maximum Duty Cycle (%) 99 98.5 CT CT =1 Maximum Duty Cycle (%) 49 CT CT =1 98 CT 48.5 48 47.5 47 =2 =2 00 pF 00 CT pF 97.5 97 96.5 96 95.5 95 10 00 pF 00 =3 30 =3 30 pF pF pF 46.5 100 Oscillator Frequency (kHz) 1000 10 100 Oscillator Frequency (kHz) 1000 Figure 4. UCC3813-0/-2/-3 max. duty cycle vs. oscillator frequency. 6 Figure 7. UCC3813-1/-4/-5 max. duty cycle vs. oscillator frequency. UCC2813-0/-1/-2/-3/-4/-5 UCC3813-0/-1/-2/-3/-4/-5 APPLICATION INFORMATION (cont.) 16 14 12 10 C VC 8 7 F 1n 6 5 VC C =1 , 0V 0 =1 1 V, nF ICC (mA) 8 VC C n V, 1 =8 ICC (mA) F 4 3 2 1 0 0 V CC =8 1 V, nF 6 4 2 0 0 VC Loa 0V, No C=1 d VCC = 10V, N o Loa d No Load VCC = 8V, , No Loa VCC = 8V d 100 200 300 400 500 600 700 800 900 1000 100 200 300 400 500 600 700 800 900 1000 Oscillator Frequency (kHz) Oscillator Frequency (kHz) Figure 8. UCC3813-0 ICC vs. oscillator frequency. Figure 10. UCC3813-5 ICC vs. oscillator frequency. 500 450 400 UCC1803/5 1.1 1.0 0.9 0.8 0.7 0.6 0 -55-50 Dead Time (ns) 350 300 250 200 150 100 50 0 100 200 300 400 500 600 700 800 900 1000 CT (pF) UCC1800/1/2/4 COMP to CS Offset (Volts) Slope = 1.8mV/°C -25 0 25 50 75 100 125 Temperature (°C) Figure 9. Dead time vs. CT, RT = 100k. Figure 11. COMP to CS offset vs. temperature, CS = 0V. 7 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. 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