isl6755 Intersil Corporation, isl6755 Datasheet
isl6755
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isl6755 Summary of contents
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... Data Sheet ZVS Full-Bridge PWM Controller with Average Current Limit The ISL6755 is a high-performance extension of the Intersil family of full-bridge ZVS controllers. Like the ISL6753, it achieves ZVS operation by driving the upper bridge FETs at a fixed 50% duty cycle while the lower bridge FETS are trailing-edge modulated with adjustable resonant switching delays ...
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Functional Block Diagram VDD VREF UVLO OVER- TEMPERATURE PROTECTION GND VREF RESDEL IOUT 4X OSCILLATOR CT RTD CTBUF SS 50% PWM STEERING LOGIC PWM SAMPLE + AND HOLD - 1.00V OVER CURRENT COMPARATOR PWM COMPARATOR 80mV VREF + - 0.33 ...
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... Q6B Q4 VIN- T2 CR1 R10 VDD BIAS CR3 T3 Q2 R20 Q5A Q5B C11 Q10A C10 Q9A Q9B Q10B Q3 Q7A Q7B U1 R11 ISL6755 VERR VREF 2 CTBUF SS 19 R19 3 RTD VDD RESDEL OUTLL OUTLR 6 FB2 OUTUL 15 7 FB1 OUTUR 14 ...
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... Latchup (Note Class II, Level B @ +85°C Operating Conditions Temperature Range ISL6755AAxx . . . . . . . . . . . . . . . . . . . . . . . . . .-40°C to +105°C Supply Voltage Range (Typical 9VDC to 16VDC CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and result in failures not covered by warranty ...
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... Frequency Variation with VDD Temperature Stability Charge Current Discharge Current Gain CT Valley Voltage CT Peak Voltage CT Pk-Pk Voltage RTD Voltage RESDEL Voltage Range CTBUF Gain ( CTBUFP-P CTP-P 5 ISL6755 < 20V, RTD = 10.0kΩ 470pF TEST CONDITIONS V = 1.1V RAMP T = +25° 0.3V RAMP VERR < 0.6V VERR = 4 ...
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... This is the maximum duty cycle achievable using the specified values of RTD and CT. Larger or smaller maximum duty cycles may be obtained using other values for these components. See Equations 1 through 5. 6. Adjust V below the UVLO stop threshold prior to setting at 7V ISL6755 < 20V, RTD = 10.0kΩ 470pF TEST CONDITIONS ...
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... RTD. RTD - This is the oscillator timing capacitor discharge current control pin. The current flowing in a resistor connected between this pin and GND determines the 7 ISL6755 110 FIGURE 2. CT DISCHARGE CURRENT GAIN vs RTD CURRENT ...
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... It may be used for slope compensation. Functional Description Features The ISL6755 PWM is an excellent choice for low cost ZVS full-bridge applications employing conventional output rectification. If synchronous rectification is required, please consider the ISL6752 or ISL6551 products. With the ISL6755’s many protection and control features, a highly flexible design with minimal external components is possible ...
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... D – Soft-Start Operation The ISL6755 features a soft-start using an external capacitor in conjunction with an internal current source. Soft-start reduces component stresses and surge currents during start-up. Upon start-up, the soft-start circuitry limits the error voltage input (VERR value equal to the soft-start voltage. The output pulse width increases as the soft-start capacitor voltage increases ...
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... ISL6755 The EA available on the ISL6755 may also be used as the voltage EA for the voltage feedback control loop rather than the current EA as described above. An external op-amp may be used as either the current or voltage EA providing the circuit is not allowed to source current into VERR ...
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... Slope compensation may be accomplished by summing an external ramp with the current feedback signal or by subtracting the external ramp from the ISL6755 RAMP 13 GND 12 GND 11 ⎞ ...
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... Ve, then Equation 19 is still valid for the CS value (EQ. 16) by the external ramp must be reduced by ΔV Adding slope compensation is accomplished in the ISL6755 is the CT using the CTBUF signal. CTBUF is an amplified representation of the sawtooth signal that appears on the CT pin offset from ground by 0.4V and is 2x the peak-to- peak amplitude of CT (0.4V to 4.4V). A typical application ⋅ ...
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... Equations 23 and 24 require modification. Equation 23 becomes: ΔV V – using Equation 19 91mV , R’ , using Equation 25 RAMP ⋅ --------------------- - VREF 19 ISL6755 GND 12 GND 11 (EQ. 26) FN6442.1 September 29, 2008 ...
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... CT and will reduce the oscillator frequency. ZVS Full-Bridge Operation The ISL6755 is a full-bridge zero-voltage switching (ZVS) PWM controller that behaves much like a traditional hard-switched topology controller. Rather than drive the diagonal bridge switches simultaneously, the upper switches ...
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... VIN- FIGURE 16. UPPER SWITCH TOGGLE AND RESONANT TRANSITION 15 ISL6755 The second power transfer period commences when switch LL closes. With switches UR and LL on, the primary and secondary currents flow as indicated in Figure 17. VIN VIN- The power transfer period terminates when switch LL turns off as determined by the PWM ...
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... ZVS resonant transition is load dependent. If the leakage inductance is not able to store sufficient energy for ZVS, a discrete inductor may be added in series with the transformer primary. 16 ISL6755 Fault Conditions A fault condition occurs if VREF or VDD fall below their I S undervoltage lockout (UVLO) thresholds or if the thermal VOUT+ protection is triggered ...
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... However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see www.intersil.com 17 ISL6755 M20. ...