InnoSwitch-CP ICs For Improved Charging Performance of Smart Mobile Devices

InnoSwitch-CP ICs For Improved Charging Performance of Smart Mobile Devices

Faster Charging: The Innoswitch-CP devices incorporate a constant power output profile which, when paired with an adaptive-voltage protocol such as Qualcomm Quick Charge 3.0 or USB-PD, permits smart mobile device makers to optimize charging time across a range of products. Developers employing adaptive charging technology achieve dramatically faster charge times, improved charging efficiency and backward compatibility with the popular 5 V USB BC 1.2 specification, all while minimizing overall thermal management and battery charging system cost.

InnoSwitch-CP ICs use Power Integrations’ innovative FluxLink technology (Fig. 1) which enables high-performance secondary-side control to be implemented with the simplicity and low component count usually associated with primary-side regulation. It also optimizes the effectiveness of output synchronous rectification, resulting in extremely high efficiency across the full load range. For example, no-load consumption at 230 VAC is less than 10 mW, while full-load efficiency exceeds 90%. InnoSwitch-CP devices easily meet all global energy efficiency regulations. 

Figure 1: FluxLink: Magneto-Inductive Coupling

InnoSwitch-CP ICs incorporate a comprehensive suite of advanced protection features including: OVP; output OCP with 3 V auto restart; hysteretic thermal shutdown and line input overvoltage protection with accurate brown-in/brown-out thresholds. Devices are fully compliant with safety and regulatory standards, including: 100% production HIPOT compliance testing equivalent to 6 kV DC/1 sec; reinforced insulation; and isolation voltage testing to above 3,500 VAC. They are UL1577 and TUV (EN60950) safety approved and EN61000-4-8 (100 A/m) and EN61000-4-9 (1000 A/m) compliant.

The InnoSwitch™-CP family of ICs dramatically simplify the development and manufacturing of low-voltage, high current power supplies, particularly those in compact enclosures or with high efficiency require¬ments. The InnoSwitch-CP architecture is revolutionary in that the devices incorporate both primary and secondary controllers, with sense elements and a safety-rated feedback mechanism into a single IC. 

InnoSwitch-CP Operation 

InnoSwitch-CP devices operate in the current limit mode. When enabled, the oscillator turns the power MOSFET on at the beginning of each cycle. The MOSFET is turned off when the current ramps up to the current limit or when the DCMAX limit is reached. Since the highest current limit level and frequency of a InnoSwitch-CP design are constant, the power delivered to the load is proportional to the primary inductance of the transformer and peak primary current squared. Hence, designing the supply involves calculating the primary inductance of the transformer for the maximum output power required. If the InnoSwitch-CP is appropriately chosen for the power level, the current in the calculated inductance will ramp up to current limit before the DCMAX limit is reached. 

InnoSwitch-CP senses the output voltage on the FEEDBACK pin using a resistive voltage divider to determine whether or not to proceed with the next switching cycle. The sequence of cycles is used to determine the current limit. Once a cycle is started, it always completes the cycle. This operation results in a power supply in which the output voltage ripple is determined by the output capacitor, and the amount of energy per switch cycle. 

ON/OFF Operation with Current Limit State Machine 

The response time of the ON/OFF control scheme is very fast compared to PWM control. This provides accurate regulation and excellent transient response. The internal clock of the InnoSwitch-CP runs all the time. At the beginning of each clock cycle, the voltage comparator on the FEEDBACK pin decides whether or not to implement a switch cycle, and based on the sequence of samples over multiple cycles, it determines the appropriate current limit. At high loads, the state machine sets the current limit to its highest value. At lighter loads, the state machine sets the current limit to reduced values. 

At near maximum load, InnoSwitch-CP will conduct during nearly all of its clock cycles. At slightly lower load, it will "skip" additional cycles in order to maintain voltage regulation at the power supply output. At medium loads, cycles will be skipped and the current limit will be reduced. At very light loads, the current limit will be reduced even further. Only a small percentage of cycles will occur to satisfy the power consumption of the power supply. 

Availability and Price

The INN2214K IC delivers 15 W output power for universal voltage chargers and adapters, while the larger INN2215K part delivers up to 22 W for similar applications. InnoSwitch-CP samples are available now. Devices are priced at $0.90 in 10,000-piece quantities. 

More information: Power Integrations