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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
BiCMOS LOW POWER CURRENT MODE PWM CONTROLLER
FEATURES DESCRIPTION
UCC38C4x family is a high-performance currentmode PWM controller. It is an enhanced BiCMOS version with pin-for-pin compatibility to the industry standard UC384xA family and UC384x family of PWM controllers. In addition, lower startup voltage versions of 7 V are offered as UCC38C40 and UCC38C41. Providing necessary features to control fixed frequency, peak current-mode power supplies, this family offers the following performance advantages. The device offers high-frequency operation up to 1 MHz with low start-up and operating currents, thus minimizing start-up loss and low operating power consumption for improved efficiency. The device also features a very fast current-sense-to-output delay time of 35 ns and a 1 A peak output current capability with improved rise and fall times for driving large external MOSFETs directly. The UCC38C4x family is offered in 8-pin packages, MSOP (DGK), SOIC (D) and PDIP (P).
D Enhanced Replacement for UC3842A Family D D D D D D D D D D
With Pin-to-Pin Compatibility 1-MHz Operation 50-A Standby Current, 100-A Maximum Low Operating Current of 2.3 mA at 52 kHz Fast 35-ns Cycle-by-Cycle Overcurrent Limiting 1-A Peak Output Current Rail-to-Rail Output Swings with 25-ns Rise and 20-ns Fall Times 1% Initial Trimmed 2.5-V Error Amplifier Reference Trimmed Oscillator Discharge Current New Under Voltage Lockout Versions MSOP-8 Package Minimizes Board Space
APPLICATIONS
D Switch-Mode Power Supplies D dc-to-dc Converters D Board Mount Power Modules
FUNCTIONAL BLOCK DIAGRAM
5.0 V VREF 8 VREF UVLO + + VREF GOOD LOGIC 5 GND 7 VDD
RT/CT
4
OSC (NOTE) 2.5 V + ERROR AMP 2R T S R 1V R Q Q 6 OUT
FB
2
COMP
1
CS
3 Note: Toggle flip-flop used only in UCC38C41, UCC38C44, and UCC38C45. UDG-99139
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.
Copyright 2003, Texas Instruments Incorporated
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
recommended operating conditions
MIN Input voltage, VDD Output voltage range, VOUT Average output current, IOUTW Reference output current, IOUT(ref)W Operating junction temperature, TJW -55 MAX 18 18 200 -20 150 UNIT V V mA mA C
It is not recommended that the device operate under conditions beyond those specified in this table for extended periods of time.
absolute maximum ratings over operating free-air temperature (unless otherwise noted)}w
Supply voltage (VDD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 V (MAX ICC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 mA Output current, IOUT peak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 A Output energy, capacitive load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 J Voltage rating (COMP, CS, FB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to 6.3 V (OUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to 20 V (RT/CT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to 6.3 V (VREF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V Error amplifier output sink current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mA Total Power Dissipation at TA = 25C: D package (jc = 22 C/W, ja = 40 - 70 C/W) . . . . . . . . . . 650 mW DGK package (jc = 41 C/W, ja = 238 - 269 C/W . . . . . . 350 mW P package (jc = 50 C/W, ja = 110 C/W . . . . . . . . . . . . . . 850 mW Operating junction temperature range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55C to 150C Storage temperature range Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65C to 150C Lead Temperature (Soldering, 10 seconds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300C
Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltages are with respect to ground. Currents are positive into and negative out of the specified terminals. Consult the Packaging Section of the Databook for thermal limitations and considerations of the package. AVAILABLE OPTIONS TA MAXIMUM DUTY CYCLE UVLO ON/OFF 14.5V / 9.0V 100% -40C to 105C 50% 8.4V / 7.6V 7.0V / 6.6V 14.5V / 9.0V 8.4V / 7.6V 7.0V / 6.6V 14.5V / 9.0V 100% 0 C 70C 0C to 70 C 50% 8.4V / 7.6V 7.0V / 6.6V 14.5V / 9.0V 8.4V / 7.6V SOIC-8 SMALL OUTLINE (D){ UCC28C42D UCC28C43D UCC28C40D UCC28C44D UCC28C45D UCC28C41D UCC38C42D UCC38C43D UCC38C40D UCC38C44D UCC38C45D PDIP-8 PLASTIC DIP (P) UCC28C42P UCC28C43P UCC28C40P UCC28C44P UCC28C45P UCC28C41P UCC38C42P UCC38C43P UCC38C40P UCC38C44P UCC38C45P MSOP-8 SMALL OUTLINE (DGK){ UCC28C42DGK UCC28C43DGK UCC28C40DGK UCC28C44DGK UCC28C45DGK UCC28C41DGK UCC38C42DGK UCC38C43DGK UCC38C40DGK UCC38C44DGK UCC38C45DGK
7.0V / 6.6V UCC38C41D UCC38C41P UCC38C41DGK D (SOIC-8) and DGK (MSOP-8) packages are available taped and reeled. Add R suffix to device type (e.g. UCC28C42DR) to order quantities of 2500 devices per reel. Tube quantities are 75 for D packages (SOIC-8) and 80 for DGK package (MSOP-8), and 50 for P package (PDIP-8).
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
electrical characteristics VDD = 15 V (See Note 1), RT = 10 k, CT = 3.3 nF, CVDD = 0.1F and no load on the outputs, TA = -40C to 105C for the UCC28C4x and TA = 0C to 70C for the UCC38C4x, TA = TJ (unless otherwise noted)
PARAMETER Reference Section Output voltage, initial accuracy Line regulation Load regulation Temperature stability Total output variation Output noise voltage Long term stability Output short circuit Oscillator Section Initial accuracy Voltage stability Temperature stability Amplitude Discharge current Error Amplifier Section Feedback input voltage, initial accuracy Feedback input voltage, total variation Input bias current Open-loop voltage gain (AVOL) Unity gain bandwidth Power supply rejection ratio (PSRR) Output sink current Output source current High-level output voltage (VOH) Low-level output voltage (VOL) Current Sense Section Gain Maximum input signal Power supply rejection ratio (PSRR) Input bias current CS to output delay COMP to CS offset 1. 2. 3. 4. 5. NOTE: NOTE: NOTE: NOTE: NOTE: See Note 5, 6 VFB < 2.4 V VDD = 12 V to 18 V, See Note 2, 5 2.85 0.9 3.00 1.0 70 -0.1 35 -2.0 70 3.15 1.1 V/V V dB A ns V VCOMP = 2.5 V, VCOMP = 2.5 V, VFB = 5.0 V VOUT = 2 V to 4 V See Note 2 VDD = 12 V to 18 V VFB = 2.7 V, VCOMP = 1.1 V VFB = 2.3 V, VFB = 2.7 V, VFB = 2.7 V, VCOMP = 5V RLOAD = 15 k to GND RLOAD = 15 k to VREF TA = 25C 2.475 2.45 65 1.0 60 2 -0.5 5 14 -1.0 6.8 0.1 1.1 2.500 2.50 -0.1 90 1.5 2.525 2.55 -2.0 V V A dB MHz dB mA mA V V TA = 25C, See Note 3 VDD = 12 V to 18 V TMIN to TMAX, See Note 2 RT/CT Pin peak-to-peak TA = 25C, RT/CT = 2 V, RT/CT = 2 V, See Note 4 See Note 4 7.7 7.2 50.5 53 0.2% 1% 1.9 8.4 8.4 9.0 9.5 55 1.0% 2.5% V mA mA kHz TA = 25C IOUT = 1mA VDD = 12 V to 18 V 1mA to 20mA See Note 2 See Note 2 10 Hz to 10 kHz, 1000 hours, TA = 25C, TA = 125C, See Note 2 See Note 2 -30 4.82 50 5 -45 25 -55 4.9 5.0 0.2 3 0.2 5.1 20 25 0.4 5.18 V mV mV mV/C V V mV mA TEST CONDITIONS MIN TYP MAX UNITS
VCS = 0 V 1.15 Adjust VDD above the start threshold before setting at 15 V. Ensured by design. Not production tested. Output frequencies of the UCC38C41, UCC38C44 and the UCC38C45 are half the oscillator frequency. Oscillator discharge current is measured with RT = 10 k to VREF. Parameter measured at trip point of latch with VFB = 0 V. DV COM , 0V V 900mV NOTE: 6. Gain is defined as ACS + CS DV CS
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
electrical characteristics VDD = 15 V (See Note 1), RT = 10 k, CT = 3.3 nF, CVDD = 0.1F and no load on the outputs, TA = -40C to 105C for the UCC28C4x and TA = 0C to 70C for the UCC38C4x, TA = TJ (unless otherwise noted)
PARAMETER Output Section VOUT low (RDS(on) pull-down) VOUThigh (RDS(on) pull-up) Rise tIme Fall time Undervoltage Lockout Section UCC38C42, UCC38C44 Start threshold UCC38C43, UCC38C45 UCC38C40, UCC38C41 UCC38C42, UCC38C44 Minimum operating voltage PWM Section Maximum duty cycle Minimum duty cycle Current Supply Section Start-up current (ISTART-UP) Operating supply current (IDD) NOTE 1: VDD = Undervoltage lockout start threshold (-0.5 V) VFB = VCS = 0 V 50 2.3 100 3.0 A mA UCC38C42, UCC38C43, UCC38C40, VFB < 2.4 V UCC38C44, UCC38C45, UCC38C41, VFB < 2.4 V VFB > 2.6 V 94% 47% 96% 48% 0% UCC38C43, UCC38C45 UCC38C40, UCC38C41 13.5 7.8 6.5 8 7.0 6.1 14.5 8.4 7.0 9 7.6 6.6 15.5 9.0 7.5 10 8.2 7.1 V ISINK = 200 mA ISOURCE = 200 mA TA = 25C, TA = 25C, CLOAD = 1 nF CLOAD = 1 nF 5.5 10 25 20 15 25 50 40 ns TEST CONDITIONS MIN TYP MAX UNITS
Adjust VDD above the start threshold before setting at 15 V. PDIP (P) or SOIC (D) PACKAGE (TOP VIEW) MSOP (DGK) PACKAGE (TOP VIEW)
COMP FB CS RT/CT
1 2 3 4
8 7 6 5
VREF VDD OUT GND
COMP FB CS RT/CT
1 2 3 4
8 7 6 5
VREF VDD OUT GND
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
pin assignments
COMP: This pin provides the output of the error amplifier for compensation. In addition, the COMP pin is frequently used as a control port by utilizing a secondary-side error amplifier to send an error signal across the secondary-primary isolation boundary through an opto-isolator. CS: The current sense pin is the non-inverting input to the PWM comparator. This is compared to a signal proportional to the error amplifier output voltage. A voltage ramp can be applied to this pin to run the device with a voltage mode control configuration. FB: This pin is the inverting input to the error amplifier. The non-inverting input to the error amplifier is internally trimmed to 2.5 V 1%. GND: Ground return pin for the output driver stage and the logic level controller section. OUT: The output of the on-chip drive stage. OUT is intended to directly drive a MOSFET. The OUT pin in the UCC38C40, UCC38C42 and UCC38C43 is the same frequency as the oscillator, and can operate near 100% duty cycle. In the UCC38C41, UCC38C44 and the UCC38C45, the frequency of OUT is one-half that of the oscillator due to an internal T flipflop. This limits the maximum duty cycle to < 50%. RT/CT: Timing resistor and timing capacitor. The timing capacitor should be connected to the device ground using minimal trace length. VDD: Power supply pin for the device. This pin should be bypassed with a 0.1-F capacitor with minimal trace lengths. Additional capacitance may be needed to provide hold up power to the device during startup. VREF: 5-V reference. For stability, the reference should be bypassed with a 0.1-F capacitor to ground using the minimal trace length possible.
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
APPLICATION INFORMATION
This device is a pin-for-pin replacement of the bipolar UC3842 family of controllers, the industry standard PWM controller for single-ended converters. Familiarity with this controller family is assumed. The UCC28C4x/UCC38C4x series is an enhanced replacement with pin-to-pin compatibility to the bipolar UC284x/UC384x and UC284xA/UC384xA families. The new series offers improved performance when compared to older bipolar devices and other competitive BiCMOS devices with similar functionality. Note that these improvements discussed below generally consist of tighter specification limits that are a subset of the older product ratings, maintaining drop-in capability. In new designs these improvements can be utilized to reduce the component count or enhance circuit performance when compared to the previously available devices.
advantages
This device increases the total circuit efficiency whether operating off-line or in dc input circuits. In off-line applications the low start-up current of this device reduces steady state power dissipation in the startup resistor, and the low operating current maximizes efficiency while running. The low running current also provides an efficiency boost in battery operated supplies. low voltage operation Two members of the UCC38C4x family are intended for applications that require a lower start-up voltage than the original family members. The UCC38C40 and UCC38C41 have a turn-on voltage of 7.0 V typical and exhibit hysteresis of 0.4 V for a turn-off voltage of 6.6 V. This reduced start-up voltage enables use in systems with lower voltages, such as 12-V battery systems which are nearly discharged. high speed operation The BiCMOS design allows operation at high frequencies that were not feasible in the predecessor bipolar devices. First, the output stage has been redesigned to drive the external power switch in approximately half the time of the earlier devices. Second, the internal oscillator is more robust with less variation as frequency increases. In addition, the current sense to output delay has been reduced by a factor of three, to 45ns typical. These features combine to provide a device capable of reliable high frequency operation. The UCC38C4x family oscillator is true to the curves of the original bipolar devices at lower frequencies yet extends the frequency programmability range to at least 1MHz. This allows the device to offer pin to pin capability where required yet capable of extending the operational range to the higher frequencies typical of latest applications. When the original UC3842 was released in 1984 most switching supplies operated between 20kHz and 100kHz. Today, the UCC38C4x can be used in designs cover a span roughly ten times higher than those numbers. start/run current improvements The start-up current is only 60 A typical, a significant reduction from the bipolar device's ratings of 300uA (UC384xA). For operation over the temperature range of -40 to 85C the UCC28C4x devices offer a maximum startup current of 100 A, an improvement over competitive BiCMOS devices. This allows the power supply designer to further optimize the selection of the startup resistor value to provide a more efficient design. In applications where low component cost overrides maximum efficiency the low run current of 2.3 mA, typical, may allow the control device to run directly through the single resistor to (+) rail, rather than needing a bootstrap winding on the power transformer, along with a rectifier. The start/run resistor for this case must also pass enough current to allow driving the primary switching MOSFET, which may be a few milliamps in small devices.
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
APPLICATION INFORMATION
1% initial reference voltage The BiCMOS internal reference of 2.5 V has an enhanced design and utilizes production trim to allow initial accuracy of 1% at room temperature and 2% over the full temperature range. This can be used to eliminate an external reference in applications that do not require the extreme accuracy afforded by the additional device. This is very useful for nonisolated dc-to-dc applications where the control device is referenced to the same common as the output. It is also applicable in offline designs that regulate on the primary side of the isolation boundary by looking at a primary bias winding, or perhaps from a winding on the output inductor of a buck-derived circuit. reduced discharge current variation The original UC3842 oscillator did not have trimmed discharged current, and the parameter was not specified on the datasheet. Since many customers attempted to use the discharge current to set a crude deadtime limit the UC3842A family was released with a trimmed discharge current specified at 25C. The UCC28C4x/UCC38C4x series now offers even tighter control of this parameter, with approximately 3% accuracy at 25C, and less than 10% variation over temperature using the UCC28C4x devices. This level of accuracy can enable a meaningful limit to be programmed, a feature not currently seen in competitive BiCMOS devices. The improved oscillator and reference also contribute to decreased variation in the peak to peak variation in the oscillator waveform, which is often used as the basis for slope compensation for the complete power system. soft-start The following diagram provides a typical soft-start circuit for use with the UCC38C42. The values of R and C should be selected to bring the COMP pin up at a controlled rate, limiting the peak current supplied by the power stage. After the soft-start interval is complete the capacitor continues to charge to VREF, effectively removing the PNP transistor from circuit considerations. The optional diode in parallel with the resistor forces a soft-start each time the PWM goes through UVLO and the reference (VREF) goes low. Without the diode,the capacitor otherwise remains charged during a brief loss of supply or brown-out, and no soft-start is enabled upon reapplication of VIN.
VREF 8 UCC38C42 COMP 1
GND 5
Figure 1
UDG-01072
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
APPLICATION INFORMATION
oscillator synchronization The UCC38C4x oscillator has the same synchronization characteristics as the original bipolar devices. Thus, the information in the Application Note U-100A, UC3842/3/4/5 Provides Low-Cost Current-Mode Control, (TI Literature No. SLUA143) still applies. The application note describes how a small resistor from the timing capacitor-to-ground can offer an insertion point for synchronization to an external clock, (see Figures 2 and 3). Figure 2 shows how the UCC38C42 can be synchronized to an external clock source. This allows precise control of frequency and dead time with a digital pulse train.
8 RT SYNCHRONIZATION CIRCUIT INPUT CT 4
VREF
RT / CT
24 W
UCC38C42 PWM
UDG-01069
Figure 2. Oscillator Synchronization Circuit
CLOCK INPUT
UPPER THRESHOLD LOW HIGH LOW LOWER THRESHOLD
PWM OUT
ON .
OFF .
ON .
OUTPUT A
VCT (ANALOG)
UPPER THRESHOLD VCT
VSYNC (DIGITAL)
LOWER THRESHOLD COMBINED
UDG-01070
Figure 3. Synchronization to an External Clock
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
APPLICATION INFORMATION
precautions The absolute maximum supply voltage is 20 V, including any transients that may be present. If this voltage is exceeded, device damage is likely. This is in contrast to the predecessor bipolar devices, which could survive up to 30 V. Thus, the supply pin should be decoupled as close to the ground pin as possible. Also, since no clamp is included in the device, the supply pin should be protected from external sources which could exceed the 20 V level. Careful layout of the printed board has always been a necessity for high frequency power supplies. As the device switching speeds and operating frequencies increase the layout of the converter becomes increasingly important. This 8-pin device has only a single ground for the logic and power connections. This forces the gate drive current pulses to flow through the same ground that the control circuit uses for reference. Thus, the interconnect inductance should be minimized as much as possible. One implication is to place the device (gate driver) circuitry close to the MOSFET it is driving. Note that this can conflict with the need for the error amplifier and the feedback path to be away from the noise generating components. circuit applications Figure 4 shows a typical off-line application.
F1 T1 R10 AC INPUT 100 Vac - 240 Vac EMI FILTER REQUIRED RT1 + C12 BR1 R11 C1A C18 R12 C53 D6 C5 SEC COMMON R6 1 2 3 4 UCC38C44 COMP FB CS RT/CT REF 8 VCC 7 OUT GND 6 5 K IC3 A R R54 UDG-01071 C13 R16 Q1 IC2 C50 R50 C51 R52 R53 R50 C54 R55 D2 D51 C3 C52 R56 L50 5V OUT C55 D50 12 V OUT
IC2
Figure 4. Typical Off-Line Application Figure 5 shows the forward converter with synchronous rectification. This application provides 48 V to 3.3 V at 10 A with over 85% efficiency and uses the UCC38C42 as the secondary-side controller and UCC3961 as the primary-side startup control device.
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10
L1 4.7uH 3r3V C2 C18 T1 4700pF + Q4 + 0.1uF R21 10 Q3 PWRGND R1 32.4k C25 R27 0.047uF R26 4.7 4.7 D1 R2 1.2k Q1 R4 1.5k D5 76.8k BAR74 R3 2.4k R28 100 1 2 3 Q2 St 12 R10 1k R16 C23 C9 0.1uF C8 1uF 680pF 1 R17 6 Ref 8 R15 C6 50k C7 470pF R24 C12 20k 3300pF R14 20k 40% T2 1 R12 200 R13 2 4 300 C10 2.7nF 3 R25 20k 7.5k C11 1500pF R18 100pF 4 Rt/Ct GND 5 3 CS CS 9 20k C16 5.6nF 0.22uF 2 FB UCC38C4x OUT 6 C14 1uF D6 + C15 1uF BZX84C15LT1 Vcc 7 U2 COMP REF 8 R22 100 C13 21.5k 13 402 R6 4.7 C22 4.7nF R23 4 R5 R19 20 + C1 470uF 470uF C19 470uF C20 C17 4700pF C21 1nF R7 10k D2 R20 10
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
VinP
VinN D3 R8 R9 0.33 5.1k U1 1 OVS ucc3961 2 SD UVS 10nF 14 BAR74
U4 TPS2832 IN BOOT PGND DT Vcc HIDR BTLO LODR
8 7 6 5 C26 2uF
APPLICATION INFORMATION
UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
Figure 5. Forward Converter with Synchronous Rectification Using the UCC38C42 as the Secondary-Side Controller
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3 SS 11 Vdd 4 FB 10 Out 5 Rt PGnd 7 AGnd Vs
C3
C4
0.22uF
C24 0.1uF
R11
46.4k
C5
0.1uF
UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
TYPICAL CHARACTERISTICS
OSCILLATOR FREQUENCY vs TIMING RESISTANCE AND CAPACITANCE
10 M IDISCH - Oscillator Discharge Current - mA CT = 220 pF CT = 470 pF 1M CT = 1 nF 100 k 9.5
OSCILLATOR DISCHARGE CURRENT vs TEMPERATURE
9.0
f - Frequency - Hz
8.5
8.0
10 k CT = 4.7 nF CT = 2.2 nF 1k 1k 10 k RT - Timing Resistance - W 100 k
7.5
7.0 -50 -25 0 25 50 75 100 125 TJ - Temperature - C
Figure 6
ERROR AMPLIFIER FREQUENCY RESPONSE
100 90 80 GAIN 70 60 Gain - (dB) 50 40 30 20 10 0 1 10 100 1k 10 k 100 k 1M f - Frequency - Hz PHASE MARGIN Phase Margin - () 140 120 100 80 60 40 20 0 10 M 200 180 160 VREF - Offset Voltage - V 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 -50
Figure 7
COMP to CS OFFSET VOLTAGE vs TEMPERATURE
-25
0
25
50
75
100
125
TJ - Temperature - C
Figure 8
Figure 9
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
TYPICAL CHARACTERISTICS
REFERENCE VOLTAGE vs TEMPERATURE
VEAREF - Error Amplifier Reference Voltage - V 5.05 5.04 VREF - Reference Voltage - V 5.03 5.02 5.01 5.00 4.99 4.98 4.97 4.96 4.95 -50 2.55 2.54 2.53 2.52 2.51 2.50 2.49 2.48 2.47 2.46 2.45 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 TJ - Temperature - C TJ - Temperature - C
ERROR AMPLIFIER REFERENCE VOLTAGE vs TEMPERATURE
Figure 10
REFERENCE SHORT-CIRCUIT CURRENT vs TEMPERATURE
-35 ISC - Reference Short Circuit Current - mA -37 -39 -41 -43 -45 -47 -49 -51 -53 -55 -50 IBIAS - Error Amplifier Input Bias Current - nA 200 150 100 50 0 -50 -100 -150 -200 -25 0 25 50 75 TJ - Temperature - C 100 125 -50 -25 0
Figure 11
ERROR AMPLIFIER INPUT BIAS CURRENT vs TEMPERATURE
25 50 75 TJ - Temperature - C
100
125
Figure 12
Figure 13
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
TYPICAL CHARACTERISTICS
UNDERVOLTAGE LOCKOUT vs TEMPERATURE (UCC38C42 & UCC38C44)
16 15 VUVLO - UVLO Voltage - V 14 13 12 11 10 9 8 7 6 -50 UVLO OFF UVLO ON VUVLO - UVLO Voltage - V 9.0 8.8 8.6 8.4 8.2 8.0 7.8 7.6 7.4 7.2 7.0 -50 UVLO OFF -25 0 25 50 75 TJ - Temperature - C Figure 15 100 125 UVLO ON
UNDERVOLTAGE LOCKOUT vs TEMPERATURE (UCC38C43 & UCC38C45)
-25
0
25
50
75
100
125
TJ - Temperature - C
Figure 14
UNDERVOLTAGE LOCKOUT vs TEMPERATURE (UCC38C40 & UCC38C41)
7.3 7.2 7.1 VUVLO - UVLO Voltage - V 7.0 6.9 6.8 6.7 6.6 6.5 6.4 6.3 -50 UVLO OFF UVLO ON
-25
0
25
50
75
100
125
TJ - Temperature - C Figure 16
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13
UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
TYPICAL CHARACTERISTICS
SUPPLY CURRENT vs OSCILLATOR FREQUENCY
25 3.0 2.9 IDD - Supply Current - mA 20 1-nF LOAD IDD - Supply Current - mA 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 0 0k 200 k 400 k 600 k f - Frequency - Hz 800 k 1M 2.0 -50 NO LOAD
SUPPLY CURRENT vs TEMPERATURE
15
10 NO LOAD
5
-25
0
25
50
75
100
125
TJ - Temperature - C
Figure 17
OUTPUT RISE TIME AND FALL TIME vs TEMPERATURE
100 10% to 90% VDD = 12 V
Figure 18
MAXIMUM DUTY CYCLE vs OSCILLATOR FREQUENCY
40
35 Output Rise and Fall TIme - ns
CT = 220 pF tr (1 nF) 90
30 Duty Cycle - % tf (1 nF) 25 80
70 CT = 1 nF
20
15
60
10 -50
-25
0
25
50
75
100
125
50
0
500
1000
1500
2000
2500
TJ - Temperature - C
f - Frequency - kHz
Figure 19
Figure 20
14
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
TYPICAL CHARACTERISTICS
MAXIMUM DUTY CYCLE vs TEMPERATURE
100 UCC38C40 UCC38C42 UCC38C43 98 Maximum Duty Cycle - % 50 UCC38C41 UCC38C44 UCC38C45 49
MAXIMUM DUTY CYCLE vs TEMPERATURE
96
Output Rise and Fall TIme - ns 0 25 50 75 100 125
48
94
47
92
46
90 -50
-25
45 -50
-25
0
25
50
75
100
125
TJ - Temperature - C
TJ - Temperature - C
Figure 21
CURRENT SENSE THRESHOLD VOLTAGE vs TEMPERATURE
70 65 tD - CD to OUT Delay Time - ns 1.05 60 55 50 45 40 35 0.90 -50 30 -50 -25
Figure 22
CS TO OUT DELAY TIME vs TEMPERATURE
1.10 VCS_th - Current Sense Threshold - V
1.00
0.95
-25
0
25
50
75
100
125
0
25
50
75
100
125
TJ - Temperature - C
TJ - Temperature - C
Figure 23
Figure 24
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15
UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
MECHANICAL DATA
D (SOIC) Note: UCC38C4x is offered in an 8-pin package ONLY.
14 PINS SHOWN
PLASTIC SMALL-OUTLINE PACKAGE
0.050 (1,27) 0.020 (0,51) 0.014 (0,35) 14 8 0.008 (0,20) NOM 0.244 (6,20) 0.228 (5,80) 0.157 (4,00) 0.150 (3,81) 0.010 (0,25) M
Gage Plane
0.010 (0,25) 1 A 7 0-8 0.044 (1,12) 0.016 (0,40)
Seating Plane 0.069 (1,75) MAX 0.010 (0,25) 0.004 (0,10) 0.004 (0,10)
PINS ** DIM A MAX
8 0.197 (5,00) 0.189 (4,80)
14 0.344 (8,75) 0.337 (8,55)
16 0.394 (10,00) 0.386 (9,80) 4040047 / D 10/96
A MIN
NOTES: A. B. C. D.
All linear dimensions are in inches (millimeters). This drawing is subject to change without notice. Body dimensions do not include mold flash or protrusion, not to exceed 0.006 (0,15). Falls within JEDEC MS-012
16
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UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
MECHANICAL DATA
DGK (R-PDSO-G8)
0,38 0,25 8 5
PLASTIC SMALL-OUTLINE PACKAGE
0,65
0,25 M
0,15 NOM 3,05 2,95 4,98 4,78
Gage Plane 0,25 1 3,05 2,95 4 0-6 0,69 0,41
Seating Plane 1,07 MAX 0,15 0,05 0,10
4073329/B 04/98 NOTES: A. B. C. D. All linear dimensions are in millimeters. This drawing is subject to change without notice. Body dimensions do not include mold flash or protrusion. Falls within JEDEC MO-187
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17
UCC28C40, UCC28C41, UCC28C42, UCC28C43, UCC28C44, UCC28C45 UCC38C40, UCC38C41, UCC38C42, UCC38C43, UCC38C44, UCC38C45
SLUS458C - AUGUST 2001 - REVISED SEPTEMBER 2003
MECHANICAL DATA
P (PDIP)
0.400 (10,60) 0.355 (9,02) 8 5
PLASTIC DUAL-IN-LINE
0.260 (6,60) 0.240 (6,10)
1
4 0.070 (1,78) MAX 0.325 (8,26) 0.300 (7,62) 0.015 (0,38) 0.200 (5,08) MAX Seating Plane 0.125 (3,18) MIN 0.010 (0,25) NOM Gage Plane
0.020 (0,51) MIN
0.100 (2,54) 0.021 (0,53) 0.015 (0,38) 0.010 (0,25) M
0.430 (10,92) MAX
4040082/D 05/98 NOTES: A. All linear dimensions are in inches (millimeters). B. This drawing is subject to change without notice. C. Falls within JEDEC MS-001
18
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