RTQ2115a-qa is a multi-function IC authenticated by AEC-Q100 Grade 1, which integrates a synchronous BUCK converter and USB 2.0 high-speed data line switch output for the charging port controller, 3V ~ 36V input / 3A, and USB 2.0 high-speed data line switches. Weld-WQFN-32L 5x5 packages in good welding performance are ideal for car electronics to add USB charging downlink ports.
Let's take a look at the internal circuit block of RTQ2115a-QA:
It is probably like this to design a typical circuit diagram in the design:
The data in the figure tells us that this is a 5V3A output design circuit. The text in the upper left corner indicates that it has the pressure drop compensation capability of the output cable, which is particularly important to ensure long-term transmission of the USB cable, ensuring that the device connected thereof The resulting voltage does not become insufficient due to the load current. If you need to select a Buck converter's working mode, you can get a high level of the MODE side to get the mandatory PWM mode of operation, and the low level can be switched between PWM mode and energy-saving PSM mode. The BCM can be connected to a high level, low or floating to CDP, SDP, or DCP, and the definition of these abbreviations can be seen in the later content.
Let's first talk about the contents related to USB2.0 high-speed data line switches:
USB2.0 interface supports data transfer up to 480Mbps, which is two-line half-duplex, and the system designer needs to add a controllable bidirectional drive between the host's USB controller and the USB connector to complete the signal transmission. And receive work. If you need to set multiple USB interfaces under a single USB controller, you need to join the USB signal switching switch to achieve minute-time connection with each interface, and the USB 2.0 high-speed data line switch integrated by RTQ2115A-QA is used for this Objective, the DH + / DH-DH + / DH-in the above figure needs to connect to the USB controller's data cable, while DS + / DS- is directly connected to the USB port connector.
There are many factors that choose the USB switch to consider, which relate to the on-impedance, insertion capacitance, bandwidth, isolation, delay, etc., RTQ2115A-QA specification lists the following data, the designer can be used when selecting Use.
About the charging port controller, the following knowledge may be the most basic:
Early USB interface design did not take into account the power supply or charging of large currents, but the development of portable equipment has changed this situation, and various manufacturers have used D + / D- to identify their equipment in this interface. USB-IF has a specification that is specifically responsible for charging applications USB Battery Charging Specification. It is the most commonly mentioned that its 1.2 revision is USB BC1.2, and its purpose is to exceed USB 2.0 Specification. Defined currents get energy from dedicated chargers, hosts, hubs, and charging downlink ports or charging license devices to define detection, control, and reporting mechanisms. Why don't it do this? Because when a PD (ie Portable device, portable device) is connected to a USB host or hub, the current of the USB 2.0 specification requires PD to absorb the current smaller than:
Average 2.5mA, if the bus is in a suspended state.
100mA, if the bus does not hang, and is not configured.
500mA, if the bus does not hang, and configured to 500mA.
When this PD is connected to a charging port (such as CDP, DCP, ACA-Dock OR ACA), there is no need to be configured or obeyed to absorb sufficient large current. In order to make PD determine how much current it can draw from a Upstream USB port, a mechanism requires a mechanism that allows PD to distinguish between Standard DownStream Port and Charging Port.
The text started from BC1.2 from BC1.2 is extracted from my BC1.2 reading notes. Let's continue to excerpt several nouns to meet readers who have demand for this, and RTQ2115A-QA can also Support these port modes.
CDP: Charging DownStream Port, Charging Downlink is a downlink port that meets USB 2.0 defined in the host or hub device, which has a CDP feature defined in this specification.
When the CDP is not connected to a peripheral, if the voltage on the D + is found above the VDAT_REF but below the VLGC, the voltage equal to VDM_SRC is output on the D-on. Once the connection to the peripherals is found, the CDP no longer outputs the VDM_SRC voltage until the external disconnection is disconnected.
DCP: Dedicated Charging Port, dedicated charging port, is a downlink port on a device, which outputs power through a USB connector, but does not have enumeration (this word should be "the" relatively reasonable) device. A DCP should be able to give current IDCP average voltage VCHG. DCP D + and D- are in a short-circuit state.
SDP: Standard DownStream Port, the standard downlink port refers to the downlink port on a device that meets the definition of USB 2.0 to the host or hub. One SDP wants to have a downstream device that is not connected or in a suspended state; one complete connection but not configured, less than 100mA of the downstream device without hangs; has been configured Ok, the current without the undouked downstream device is not more than 500mA. A downstream device can be enumerated after connecting to SDP. A SDP pulls D + and D- low to the ground level by two 15kΩ resistors. An SDP can have such an capability that when the PD drives D + to the VDP_SRC, it can detect and manage its power status later. Pd needs to drive D + to VDP_SRC when the current consumption has been accepted but not connected, and the D + is driven to the VDP_SRC, see the Dead Battery Provision.
(Note: These content is a note, translated from USB BC1.2, and now look a bit wrong, so add a little annotation. In order to avoid misleading of my understanding, please rigorous readers to view the original text.)
The detection of ports of course is of course a matter that requires the supplier and the need to work together. Therefore, USB BC1.2 also specifies the way port detection, and the IC designer can design these mechanisms into IC in the specific implementation. When you understand this, you will see the RTQ2115a-qa's specifications or introduce it, see it saying that you have a charging port controller, you know how it works. In fact, RTQ2115A-QA also supports YD / T1591-2009, which is the interface standard of universal mobile phone charger, which defines the standard charger D +, D- is a short circuit together, and the support for this standard is placed in the DCP interface Under the mode.
Finally, the BUCK converter section of the RTQ2115a-QA is, after it has it, the VBUS power supply problem connected to the USB port is resolved, and the power supply range it adapted is very wide, can be at 3V ~ Opening within the 36V input voltage range, of course, this does not indicate that the input voltage is 3V, and it can provide normal 5V output. This situation is very easy to happen on the vehicle, and the large load occurs when the engine is started. The voltage pulls the very low extent, Buck can work at a very low voltage to ensure that its load can operate normally, but the normal system is allowed to be temporarily not working in this situation, just like we start When the vehicle saws a lot of equipment lights, it is the same as it is suspended.
The load capacity of the BUCK converter contained in RTQ2115A-QA is 3A, even if it makes it powers to external power through the USB C type interface. It compensates for IR pressure drop that the load current may be formed through long-term transmission to ensure that the voltage supply obtained by the final load is stable, and there is no major change due to changes in the load current.
The Buck converter is working in switch mode, and the resulting switching noise is particularly afraid of some electronic devices, and the car radio part is particularly sensitive. RTQ2115A-QA BUCK converters can work within 300kHz to 2.1MHz, and support the operating mode of the spectrum extension mode, the noise of the switch work can be assigned to a relatively wide frequency range, avoiding the radio energy concentration in which it is emitted. In a single frequency, this can reduce interference of the radio system to the lowest degree.
If the application emphasizes energy saving, it is necessary to increase the conversion efficiency as possible, which can enter the energy-saving working mode in the light-saving situation to improve efficiency. In addition to this, it is still better to work in force PWM mode. At this time, the output ripple will be relatively low, and some applications are relatively appropriate.
Since RTQ2115A-QA is targeted by the USB port with power supply, charging function, it is necessary to use different modes when connecting different loads. The operation of its Buck converter is associated with mode switching. Whenever the state of the BCM terminal is changed to implement mode switching, it will be interrupt and reset, start, and the switching time between different modes can be seen, and the specific details can be found in the product specification.
RTQ2115a-qa as a USB port solution for a vehicle electronic device, which is more considered to be more than ordinary power management devices, for example, it has adjacent pin short circuit protection functions, even because it is short-circuited. I burned yourself or not to cause smoke, burning. Its data line terminal has ± 8kV HBM electrostatic tolerance. Its package is different from WET-WQFN of general QFN, and the infiltration performance in the welding is better, and it is not easy to produce the noble welding problem.
Reprinted from Richtektechnology.
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