UC1860 UC2860 UC3860 Resonant Mode Power Supply Controller FEATURES DESCRIPTION • 3MHz VFO Linear over 100:1 Range • 5MHz Error Amplifier with Controlled Output Swing • The UC1860 family of control ICs is a versatile system for resonant mode power supply control. This device easily implements frequency modulated fixed-on-time control schemes as well as a number of other power supply control schemes with its various dedicated and programmable features. Programmable One Shot Timer— Down to 100ns • Precision 5V Reference • Dual 2A Peak Totem Pole Outputs • Programmable Output Sequence • Programmable Under Voltage Lockout • Very Low Start Up Current • Programmable Fault Management & Restart Delay • Uncommitted Comparator The UC1860 includes a precision voltage reference, a wide-bandwidth error amplifier, a variable frequency oscillator operable to beyond 3MHz, an oscillator-triggered one-shot, dual high-current totem-pole output drivers, and a programmable toggle flip-flop. The output mode is easily programmed for various sequences such as A, off, B, off; A & B, off; or A, B, off. The error amplifier contains precision output clamps that allow programming of minimum and maximum frequency. The device also contains an uncommitted comparator, a fast comparator for fault sensing, programmable soft start circuitry, and a programmable restart delay. Hic-up style response to faults is easily achieved. In addition, the UC1860 contains programmable under voltage lockout circuitry that forces the output stages low and minimizes supply current during start-up conditions. ABSOLUTE MAXIMUM RATINGS Supply Voltage (pin 19) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20V Output Current, Source or Sink (pins 17 & 20) DC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8A Pulse (0.5µs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0A Power Ground Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±0.2V Inputs (pins 1, 2, 3, 4, 8, 9, 11, 12, 13, 14, 21, 22, 23 & 24) . . . . . . . . . . . . . . . . . . . . . . -0.4 to 6V Error Amp Output Current, Source or Sink (pin 5) . . . . . . . . 2mA IVFO Current (pin 7). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2mA Comparator Output Current (pin 15) . . . . . . . . . . . . . . . . . . 5mA BLOCK DIAGRAM 10/93 Comparator Output Voltage (pin 15) . . . . . . . . . . . . . . . . . . 15V Soft Start or Restart Delay Sink Current (pins 22 & 23) . . . 5mA Power Dissipation at TA = 50°C (DIP) . . . . . . . . . . . . . . . 1.25W Power Dissipation at TA = 50°C (PLCC) . . . . . . . . . . . . . . . . 1W Lead Temperature (Soldering, 10 seconds) . . . . . . . . . . . 300°C Note: All voltages are with respect to signal ground and all currents are positive into the specified terminal. Pin numbers refer to the DIP. Refer to Packaging Section of Databook for thermal limitations and considerations of packages. UC1860 UC2860 UC3860 CONNECTION DIAGRAM PLCC-28, LCC-28 (TOP VIEW) Q or L Package DIL - 24 (TOP VIEW) J or N Package PIN PACKAGE FUNCTION FUNCTION PIN S GND 1 IVFO 2 CVFO 3 RC 4 VREF 5 CMP IN (-) 6 CMP IN (+) 7 TRIG 8 OSC DSBL 9 CMP OUT 10 N/C 11, 12 OUT A 13 PGND 14 N/C 15 VCC 16 OUT B 17 N/C 18, 19 MODE 20 SFT STRT 21 RST DLY 22 UVLO 23 FLT (-) 24 FLT (+) 25 EA IN (+) 26 EA IN (-) 27 EA OUT 28 ELECTRICAL CHARACTERISTICS: Unless otherwise stated, all specifications apply for -55°C ≤ TA ≤ 125°C for the UC1860, -25°C ≤ TA ≤ 85°C for the UC2860, 0 ≤ TA ≤ 70°C for the UC3860, VCC = 12V, CVFO = 330pF, IVFO = 0.5mA, C = 330pF, and R = 2.7k, TA = TJ. PARAMETER Reference Section Output Voltage CONDITIONS TA = 25°C, IO = 0 IO = 0, Over Temp 10 ≤ VCC ≤ 20V 0≤ IO ≤ 10mA 10Hz ≤ f ≤ 10kHz VREF = 0V Line Regulation Load Regulation Output Noise Voltage* Short Circuit Current Error Amplifier Section Input Offset Voltage 2.8 ≤ VCM ≤ 4.5V Input Bias Current Open Loop Gain dVO = 1.5V PSRR 10 ≤ VCC ≤ 20V Output Low (VO-VIVFO) -0.1 ≤ IO ≤ 0.1mA Output High (VO-VIVFO) -0.5 ≤ IO ≤ 0.5mA Unity Gain Bandwidth* RIN = 2k Oscillator Section Nominal Frequency* dF/dIOSC* 100 ≤ IVFO ≤ 500µA *Guaranteed by design but not 100% tested. MIN TYP MAX UNITS 4.95 4.93 5.00 5.05 5.07 15 25 V V mV mV µVRMS mA 2 2 50 -150 2 -15 8 500 60 70 -8 1.9 4 1 50 80 100 0 2 5 1.0 2 1.5 3 2.0 4 8 2.1 mV nA dB dB mV V MHz MHz GHz/A UC1860 UC2860 UC3860 ELECTRICAL CHARACTERISTICS: Unless otherwise stated, all specifications apply for -55°C ≤ TA ≤ 125°C for the UC1860, -25° ≤ TA ≤ 85°C for the UC2860, 0 ≤ TA ≤ 70°C for the UC3860, VCC = 12V, CVFO = 330pF, IVFO = 0.5mA, C = 330pF, and R = 2.7k, TA = TJ. PARAMETER Oscillator Section (cont’d) Trig in Threshold Trig in Open Circuit Voltage Trig in Delta (VTH-VOC) Trig in Input Resistance Minimum Trig in Pulse Width* Osc. Disable Threshold One Shot Timer On Time* Clamp Frequency* Dead Time* Output Stage Output Low Saturation Output High Saturation Rise/Fall Time* UVLO Low Saturation Output Mode Low Input Output Mode High Input Under Voltage Lockout Section VCC Comparator Threshold UVLO Comparator Threshold UVLO Input Resistance VREF Comparator Threshold Supply Current ICC ISTART CONDITIONS dV TRIG = VOC to VTH IVFO = 1.5mA IVFO =1.5mA MIN TYP MAX UNITS 1.0 0.7 0.3 5 1.0 1.4 0.9 0.5 12 3 1.4 1.8 1.1 0.7 25 10 1.8 V V V kΩ ns V 150 2.8 35 200 3.7 70 250 4.6 100 ns MHz ns 0.2 0.5 1.5 1.7 15 0.8 0.4 2.2 2.0 2.5 30 1.5 0.4 V V V V ns V V V 17.3 10.5 4.2 0.4 23 4.5 18.5 12 4.8 0.6 50 4.9 V V V V kΩ V 30 0.3 40 0.5 mA mA 2 100 10 100 10 200 30 150 mV µA µA ns 2 100 10 0.3 50 10 200 30 0.5 100 mV µA µA V ns 0.2 5 3.0 0.5 10 3.2 V µA V 20mA 200mA -20mA -200mA CLOAD = 1nF 20mA 2.0 On Off On Hysteresis UVLO = 4/VCC = 8 VCC = UVLO = VREF 16 9.5 3.6 0.2 10 VCC = 12V, VOSC DSBL = 3V UVLO pin open VCC = VCC (on) -0.3V Fault Comparator Input Offset Voltage −0.3 ≤ VCM ≤ 3V Input Bias Current VCM = 0V Input Offset Current VCM = 0V Propagation Delay To Output* ±50mV input Uncommitted Comparator Input Offset Voltage -0.3 ≤ VCM ≤ 3V Input Bias Current VCM = 0V Input Offset Current VCM = 0V Output Low Voltage IO = 2mA Propagation Delay To Sat* ±50mV input, 2.5k load to 5V Soft Start/Restart Control Section Saturation Voltage (2 pins) ISINK = 100µA Charge Current (2 pins) Restart Delay Threshold *Guaranteed by design but not 100% tested. 3 2 2.8 UC1860 UC2860 UC3860 ERROR AMPLIFIER The error amplifier is a high gain, low offset, high bandwidth design with precise limits on its output swing. The bandwidth of the amplifier is externally determined by the resistance seen at the inverting input. Unity gain bandwidth is approximately: Frequency (0dB) = 1/(2π * RIN (-) * CCOMP) The input common mode range of the amplifier is from 2.8 to 4.5V. As long as one pin is within this range, the other can go as low as zero. The output swing with respect to the lVFO pin is limited from zero to 2V. Note that pulling Sft Strt (soft start) low will lower the reference of the upper clamp. The lower clamp, however, will dominate should the upper clamp reference drop below the lower reference. The VCC comparator is used for off-line applications by leaving the UVLO pin open. In this application the supply current is typically less than 0.3mA during start-up. UNDER VOLTAGE LOCKOUT SECTION The under voltage lockout consists of three comparators that monitor VCC, UVLO and VREF. The VREF comparator makes sure that the reference voltage is sufficiently high before operation begins. When the UVLO comparator is low, the outputs are driven low, the fault latch is reset, the soft start pin is discharged, and the toggle flip-flop is loaded for output A. The UVLO comparator is used for DC to DC applications or to gate the chip on and off. To utilize its hysteretic threshold by an external resistive divider, the internal impedance of the pin must be accounted for. To run from a 5V external supply, UVLO, VCC, and VREF are tied together. ICC vs VCC 4 UC1860 UC2860 UC3860 Normally low trigger pulses are used to synchronize the oscillator to a faster clock. Normally high trigger pulses can also be used to synchronize to a slower clock. VARIABLE FREQUENCY OSCILLATOR The VFO block is controlled through 4 pins: CVFO, lVFO, Osc Dsbl (oscillator disable), and Trig (trigger input). Oscillator frequency is approximately: ONE SHOT TIMER Frequency = IVFO/(CVFO * 1V) The one shot timer performs three functions and is programmed by the RC pin. The first function is to control output driver pulse width. Secondly, it clocks the toggle flip-flop. Thirdly, it establishes the maximum allowable frequency for the VFO. One shot operation is initiated at the beginning of each oscillator cycle. The RC pin, programmed by an external resistor and capacitor to ground, is charged to approximately 4.3V and then allowed to discharge. The lower threshold is approximately 80% of the peak. On time is approximately: With a fixed capacitor and low voltage applied to Trig and Osc Dsbl, frequency is linearly modulated by varying the current into the lVFO pin. The Trig and Osc Dsbl inputs are used to modify VFO operation. If Osc Dsbl is held high, the oscillator will complete the current cycle but wait until Osc Dsbl is returned low to initiate a new cycle. If a pulse is applied to Trig during a cycle, the oscillator will immediately initiate a new cycle. Osc Dsbl has priority over Trig, but if a trigger pulse is received while Osc Dsbl is high, the VFO will remember the trigger pulse and start a new cycle as soon as Osc Dsbl goes low. Maximum Frequency vs R t(on) = 0.2 * R * C. After crossing the lower threshold, the resistor continues to discharge the capacitor to approximately 3V, where it waits for the next oscillator cycle. On Time vs R 5 VFO Frequency vs IVFO UC1860 UC2860 UC3860 3.0V. As long as one of the inputs is within this range, the other can be as high as 5V. FAULT MANAGEMENT SECTION During UVLO, the fault management section is initialized. The latch is reset, and both Sft Strt (soft start) and Rst Dly (restart delay) are pulled low. When Sft Strt is low, it lowers the upper clamp of the error amplifier. As Sft Strt increases in voltage, the upper clamp increases from a value equal to the lower clamp until it is 2V more positive. A capacitor to ground from the Sft Strt pin will control the start rate. The high speed fault comparator will work over the input common mode range of -0.3 to 3.0V. When a fault is sensed, the one shot is immediately terminated, Sft Strt is pulled low, and Rst Dly is allowed to go high. Three modes of fault disposition can easily be implemented. If Rst Dly is externally held low, then a detected fault will shut the chip down permanently. If the Rst Dly pin is left open, a fault will simply cause an interruption of operation. If a capacitor is connected from Rst Dly to ground, then hic-up operation is implemented. The hic-up time is: UNCOMMITTED COMPARATOR The uncommitted comparator, biased from the reference voltage, operates independently from the rest of the chip. The open collector output is capable of sinking 2mA. The inputs are valid in the common mode range of -0.3 to t (off) = 600 kohm * C(Rst Dly). Input Bias Current Input Voltage 6 UC1860 UC2860 UC3860 OPEN LOOP LABORATORY TEST FIXTURE may be applied. When the switch is set to the resistive divider, the chip will operate in consecutive mode (ie: A,B, off,...) The open loop laboratory test fixture is designed to allow familiarization with the operating characteristics of the UC3860. Note the pin numbers apply to the DlP. S3 allows input of an external logic signal to disable the oscillator. To get started, preset all the options as follows: S4 demonstrates the uncommitted comparator. When set to output A, the comparator will accelerate the discharge of pin 9, shortening the output pulse. Adjust the error amplifier variable resistor pot (R1) so the wiper is at a high potential. Open the lVFO resistor switch (S1). S5 shorted to ground will disable the chip and the outputs will be low. If the switch is open, the VCC start and stop thresholds are 17 and 10V. Switched to the resistive divider, the thresholds are approximately 12 and 10V. Throw the Trig switch (S2) to ground. Throw the Osc Dsbl switch (S3) to ground. Throw the uncommitted comparator switch (S4) to ground. S6 sets the mode of the toggle flip-flop. When grounded, the outputs operate alternately. Switched to 5V, the outputs switch in unison. (Note: If S6 and S2 are set for unison operation and triggered consecutive outputs, the chip will free run at the maximum frequency determined by the one shot.) Throw the UVLO switch (S5) to the resistive divider. Throw the Out Mode switch (S6) to ground. Open the restart delay switch (S7). Throw the fault switch (S8)to ground. In this configuration, the chip will operate for Vcc greater than 12V. Adjustment of the following controls allows examination of specific features. S7 open allows the chip to restart immediately after a fault sense has been removed. When grounded, it causes the chip to latch off indefinitely. This state can be reset by UVLO, VCC, or opening the switch. Connected to IµF programs a hic-up delay time of 600 ms. R1 adjusts the output of the error amp. Notice the voltage at pin 5 is limited from 0 to 2V above the voltage at pin 7. S1 changes the error amp output to VFO gain. With S1 open, the maximum frequency is determined by the error amp output. With S1 closed, the one shot will set the maximum frequency. S8 allows the simulation of a fault state. When flipped to the RC network, the comparator monitors scaled average voltage of output B. Adjusting frequency will cause the comparator to sense a ’fault’ and the chip will enter fault sequence. S2 demonstrates the trigger. An external trigger signal 7 UC1860 UC2860 UC3860 OUTPUT STAGE BYPASS NOTE The two totem pole output stages can be programmed by Mode to operate alternately or in unison. When Mode is low the outputs alternate. During UVLO, the outputs are low. The reference should be bypassed with a 0.1µF ceramic capacitor from the VREF pin directly to the ground plane near the Signal Ground pin. The timing capacitors on CVFO and RC should be treated likewise. VCC, however, should be bypassed with a ceramic capacitor from the VCC pin to the section of ground plane that is connected to Power Ground. Any required bulk reservoir capacitor should parallel this one. The two ground plane sections can then be joined at a single point to optimize noise rejection and minimize DC drops. Extreme care needs to be exercised in the application of these outputs. Each output can source and sink transient currents of 2A or more and is designed for high values of dl/dt. This dictates the use of a ground plane, shielded interconnect cables, Schottky diode clamps from the output pins to Pwr Gnd (power ground), and some series resistance to provide damping. Pwr Gnd should not exceed ±0.2V from signal ground. Output Saturation Voltage vs Load Current Output Rise & Fall Time vs Load Capacitance Output Saturation Voltage vs Load Current UNITRODE INTEGRATED CIRCUITS 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. 603-424-2410 • FAX 603-424-3460 8 PACKAGE OPTION ADDENDUM www.ti.com 18-Sep-2008 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty Lead/Ball Finish MSL Peak Temp (3) UC1860J OBSOLETE CDIP J 24 TBD Call TI Call TI UC1860J883B OBSOLETE CDIP J 24 TBD Call TI Call TI UC2860DW OBSOLETE SOIC DW 24 TBD Call TI Call TI UC2860DWTR OBSOLETE SOIC DW 24 TBD Call TI Call TI UC2860N OBSOLETE PDIP N 24 TBD Call TI Call TI UC2860Q OBSOLETE PLCC FN 28 TBD Call TI Call TI UC2860QTR OBSOLETE PLCC FN 28 TBD Call TI Call TI UC3860DW OBSOLETE SOIC DW 24 TBD Call TI Call TI UC3860DWTR OBSOLETE SOIC DW 24 TBD Call TI Call TI UC3860N OBSOLETE PDIP N 24 TBD Call TI Call TI UC3860Q OBSOLETE PLCC FN 28 TBD Call TI Call TI UC3860QTR OBSOLETE PLCC FN 28 TBD Call TI Call TI (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. 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