InnoSwitch5-ProInnoSwitch5-Pro Functional Description pin voltage fal s below this threshold, it must rise to V to re-enable SHUNT turn-on of the power switch. The InnoSwitch5-Pro combines a high-voltage power switch, along with both primary-side and secondary-side control ers in one device. Primary BYPASS Pin Overvoltage Function The PRIMARY BYPASS pin has an optional latching OV protection The architecture incorporates a novel inductive coupling feedback feature. A Zener diode in paral el with the resistor in series with the scheme (FluxLink) using the package lead frame and bond wires to PRIMARY BYPASS pin capacitor is typical y used to detect an provide a safe, reliable, and cost-effective means to transmit overvoltage on the primary bias winding and activate the protection accurate, output voltage and current information from the secondary mechanism. In the event that the current into the PRIMARY BYPASS control er to the primary control er. pin exceeds I , the device will latch-off or disable the power switch SD The InnoSwitch5-Pro secondary control er consists of a transmitter switching for a time t , after which time the control er will restart AR(OFF) circuit that is magnetical y coupled to the primary receiver, an I2C and attempt to return to regulation. interface to control power supply parameters and telemetry functions, VOUT OV protection is also included as an integrated feature on the a 4.5 V regulator on the SECONDARY BYPASS pin, synchronous secondary controller (see Output Voltage Protection). rectifier FET driver, oscillator and timing functions, and a host of integrated protection features. Over-Temperature Protection The thermal shutdown circuitry senses the primary switch die The primary control er on lnnoSwitch5-Pro is a Quasi-Resonant (QR) temperature. The threshold is set to T with either a hysteretic or flyback control er that has the ability to operate in continuous SD latch-off response. conduction mode (CCM). The control er uses both variable frequency and variable current limit control schemes. The primary control er Hysteretic response: If the die temperature rises above the threshold, consists of a frequency jitter oscillator; a receiver circuit magnetical y the power switch is disabled and remains disabled until the die coupled to the secondary control er, a current limit control er, 5 V temperature fal s by T at which point switching is re-enabled. A SD(H) regulator on the PRIMARY BYPASS pin, bypass overvoltage detection large amount of hysteresis is provided to prevent over-heating of the circuit, a lossless input line sensing circuit, current limit selection PCB due to a continuous fault condition. circuitry, over-temperature protection and leading edge blanking. Latch-off response: If the die temperature rises above the threshold Figure 3 and Figure 4 show the functional block diagrams of the the power switch is disabled. The latching condition is reset by primary and secondary control er with the most important features. bringing the PRIMARY BYPASS pin below V or by going below BPP(RESET) the UNDER/OVER INPUT VOLTAGE pin UV (I ) threshold. Primary Controller UV- InnoSwitch5-Pro is a variable frequency control er al owing CCM/CrM/ 1.05 DCM operation for enhanced efficiency and extended output power capability. ) 1.00 PRIMARY BYPASS Pin Regulator(A -9094-121019 PI The PRIMARY BYPASS pin has an internal regulator that charges the 0.95 PRIMARY BYPASS pin capacitor to V by drawing current from the LIM BPP DRAIN pin whenever the power switch is off. The PRIMARY BYPASS 0.90 pin is the internal supply voltage node. When the power switch is on, the device operates from the energy stored in the PRIMARY BYPASS pin capacitor. 0.85 ormalized I In addition, a shunt regulator clamps the PRIMARY BYPASS pin N 0.80 voltage to V when current is provided to the PRIMARY BYPASS SHUNT pin through an external resistor. This al ows the InnoSwitch5-Pro to be powered external y through a bias winding, decreasing the no-load 0.75 consumption to less than 30 mW in a 5 V output design. 30 50 70 90 110 130 150 Primary Bypass ILIM ProgrammingSteady-State Switching Frequency (kHz) InnoSwitch5-Pro ICs al ows the user to adjust current limit (ILIM) settings through the selection of the PRIMARY BYPASS pin capacitor Figure 6. Normalized Primary Current vs. Frequency. value. A ceramic capacitor can be used. Current Limit Operation There are 2 selectable capacitor sizes – 0.47 mF and 4.7 mF for setting The primary-side control er has a current limit threshold ramp that is standard and increased ILIM settings respectively. inversely proportional to the time from the end of the previous primary switching cycle (i.e. from the time the primary switch turns Primary Bypass Undervoltage Threshold off at the end of a switching cycle). The PRIMARY BYPASS pin undervoltage circuitry disables the power switch when the PRIMARY BYPASS pin voltage drops below ~4.5 V This characteristic produces a primary current limit that increases as (V ‒ V ) in steady-state operation. Once the PRIMARY BYPASS the switching frequency (load) increases (Figure 6). BPP BP(H) 4 Rev. C 01/24 www.power.com
