P9222-R/RN Datasheet

© 2019-2022 Renesas Electronics Corporation

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May 5, 2022

8.3 VRECT Pin

The efficiency of the full-bridge rectifier in the P9222-R/RN is increased by implementing it as a synchronous rectifier.

The rectifier comprises four self-driven switches that work in a full synchronous mode of operation when the load is higher than 150mA. Below

that threshold, the rectifier works in half-synchronous rectification mode. At power-up, when the voltage is below the UVLO threshold, the

rectifier works by using the body diodes associated with the NMOS transistors. The BST capacitors are used to provide power to drive the gates

of high-side NMOS switches.

8.4 Enable Pin

The P9222-R/RN offers an active LOW enable function that allows the host AP to control when wireless power will be enabled. The /EN enable

pin (C4) must be actively pulled-up or pulled-down using the AP to drive the pin directly, or by using an external resistor to passively control the

default state. The /EN pin is a push-pull general purpose input/output (GPIO) type input and will consume current when driven HIGH while the

P9222-R/RN is not powered. It is recommended that one of the circuits shown in Figure 27 be followed.

The /EN pin can be actively controlled (AP I/O directly connected to /EN pin) or passively controlled depending on system requirements. Since

the AP must be used to control the P9222-R/RN enable pin, power will be consumed by the biasing resistor when the state is changed from the

default if using a passive control scheme – this may be needed to support AP sleep modes. Typical systems will use the P9222-R/RN set up to

be enabled by default in order to save the most power, and will disable wireless charging when wired charging is used or some other function

is being performed that requires wireless charging to remain disabled. One of the diagrams in Figure 27 must be used to set the default /EN pin

state for the P9222-R/RN.

Figure 27. P9222-R/RN Recommended Enable Default State Configurations

When using the “active enable control,” it is important to always force the /EN pin into a known state, and the /EN pin should never be left

floating. For example, in some applications when the battery is dead or when the AP is in sleep mode, the AP may not be actively driving the

/EN pin. In order to prevent the /EN pin from floating in such cases, a pull-down resistor should be added.

8.5

Transient Voltage Suppressor Diodes (TVS)

Transient Voltage Suppressor diodes can be added to the design from the AC1 and AC2 nodes to GND, or from AC1 to AC2 (D10, D2, D3, as

shown in the reference schematic). This component is useful to rapidly limit incoming ESD surges, or situations when the Tx incoming power

exceeds the expected power and Vrect voltage rises above target and over 15V in less than 10µs to aid in voltage limiting the incoming AC

waveforms. A balance in Reverse Standoff Voltage (VRWM), Clamping Voltage (VCL), Break-down Voltage (VBR) relative to the expected Vrect

operating voltage Vrect (be sure minimum VBR is less than maximum operating Vrect value and that VCL is less than Vrect Absolute maximum

voltage) should be reached. The following guidance should be used for the P9222-R/RN when selecting TVS diodes:



VRWM = 12V maximum



VBR = 14.6 V minimum at 5mA



VCL = 22 V maximum at 1App

When TVS diodes are used, it is recommended to place them as close to the coil on the respective nodes as possible to shunt high voltages

away from the P9222-R/RN. Zener diodes can also be used to limit voltage levels, and the Zener voltage should be above the working voltage

of the node and below the absolute maximum voltage of the pin connected to the node.