InnoSwitch3-ProInnoSwitch3-Pro Functional DescriptionPrimary Bypass Undervoltage Threshold The PRIMARY BYPASS
pin undervoltage circuitry disables the power The InnoSwitch3-Pro combines a high-voltage power switch, along switch when the PRIMARY BYPASS
pin voltage drops below ~4.5 V with both primary-side and secondary-side control ers in one device. (V - V ) in steady-state operation. Once the PRIMARY BYPASS
BPP BP(H) The architecture incorporates a novel inductive coupling feedback pin voltage fal s below this threshold, it must rise to V to re-enable BP scheme using the package lead frame and bond wires to provide a turn-on of the power switch. safe, reliable, and low-cost means to communicate accurate direct Primary Bypass Output Overvoltage Function sensing of the output voltage and output current on the secondary IC The PRIMARY BYPASS pin has a OV protection feature. A Zener diode to the primary IC. in paral el with the resistor in series with the PRIMARY BYPASS pin capacitor is typical y used to detect an overvoltage on the primary The primary control er on InnoSwitch3-Pro is a Quasi-Resonant (QR) bias winding and activate the protection mechanism. In the event flyback control er that has the ability to operate in continuous that the current into the PRIMARY BYPASS pin exceeds ISD, the conduction mode (CCM). The control er uses both variable frequency device will latch-off or auto-restart depending on the H-code. and variable current control schemes. The primary control er consists of a frequency jitter oscillator; a receiver circuit magnetical y coupled to VOUT OV protection is also included as an integrated feature on the the secondary control er, a current limit control er, 5 V regulator on secondary controller. the PRIMARY BYPASS pin, audible noise reduction engine for light load operation, bypass overvoltage detection circuit, a lossless input Over-Temperature Protection line sensing circuit, current limit selection circuitry, over-temperature The thermal shutdown circuitry senses the primary switch die protection and leading edge blanking. temperature. The threshold is set to T with either a hysteretic or SD latch-off response depending on the H-code. The InnoSwitch3-Pro secondary control er consists of a transmitter circuit that is magnetical y coupled to the primary receiver, an I Hysteretic response: If the die temperature rises above the threshold, 2C interface to control power supply parameters and telemetry functions, the power switch is disabled and remains disabled until the die a 4.4 V regulator on the SECONDARY BYPASS
pin, synchronous temperature fal s by T at which point switching is re-enabled. A SD(H) rectifier FET driver, QR mode circuit, oscillator and timing functions, large amount of hysteresis is provided to prevent over-heating of the and a host of integrated protection features. PCB due to a continuous fault condition. Figure 3 and Figure 4 show the functional block diagrams of the Latch-off response: If the die temperature rises above the threshold primary and secondary control er with the most important features. the power switch is disabled. The latching condition is reset by bringing the PRIMARY BYPASS pin below V or by going below BPP(RESET) Primary Controller the UNDER/OVER INPUT VOLTAGE pin UV (I ) threshold. UV- InnoSwitch3-Pro has variable frequency QR control er plus CCM/CrM/ DCM operation for enhanced efficiency and extended output power capability. 1.05 PRIMARY BYPASS Pin Regulator The PRIMARY BYPASS pin has an internal regulator that charges the 1.0 PRIMARY BYPASS pin capacitor to V by drawing current from the ) BPP -8205-120516 DRAIN pin whenever the power switch is off. The PRIMARY BYPASS (A PI pin is the internal supply voltage node. When the power switch is on, 0.95 LIM the device operates from the energy stored in the PRIMARY BYPASS pin capacitor. 0.9 In addition, a shunt regulator clamps the PRIMARY BYPASS
pin voltage to V when current is provided to the PRIMARY BYPASS
SHUNT 0.85 pin through an external resistor. This al ows the InnoSwitch3-Pro to ormalized I be powered external y through a bias winding, decreasing the no-load N consumption to less than 30 mW in a 5 V output design. 0.8 Primary Bypass ILIM Programming 0.75 InnoSwitch3-Pro ICs al ows the user to adjust current limit (ILIM) settings through the selection of the PRIMARY BYPASS
pin capacitor 30 40 50 60 70 80 90 100 value. A ceramic capacitor can be used. Steady-State Switching Frequency (kHz) There are 2 selectable capacitor sizes - 0.47 mF and 4.7 mF for setting Figure 6. Normalized Primary Current vs. Frequency. standard and increased ILIM settings respectively. 4 Rev. G 07/19 www.power.com Document Outline Product Highlights Description Output Power Table Pin Functional Description InnoSwitch3-Pro Functional Description Primary Controller Secondary Controller Register Definition Command Registers Telemetry (Read-back) Registers I2C Connection I2C Example Waveforms Applications Example Key application Considerations Selection of Components Components for InnoSwitch3-Pro IC Primary-Side Circuit Components for InnoSwitch3-PRO Secondary-Side Circuit Recommendations for Circuit Board Layout Layout Example Recommendations for Transformer Design Application Considerations for INN3379C and INN3370C Only Quick Design Checklist Theremal Resistance Test Conditions for INN3379C and INN3370C Absolute Maximum Ratings Thermal Resistance Key Electrical Characteristics Typical Performance Curves InSOP-24D Package Drawing Part Ordering Table MSL Table ESD and Latch-Up Table Part Ordering Information
