Digital Imaging

The ADP5350, a power management IC (PMIC), combines one high performance buck regulator for single Li-Ion/Li-Ion polymer battery charging, a fuel gauge, a highly programmable boost regulator for LED backlight illumination, and three 150 mA LDO regulators.

The ADP5350 operates in trickle charge mode and in constant current (CC) and constant voltage (CV) fast charge mode. It features an internal field effect transistor (FET) that permits battery isolation on the system power side.

The ADP5350 fuel gauge is a space-saving and low current consuming solution. It is optimal for rechargeable Li-Ion battery-powered devices, and features a voltage-based, battery SOC measurement function.

The ADP5350 boost regulator operates at a 1.5 MHz switching frequency. It can be operated as a constant voltage regulator or as a supplemental constant current regulator for multiple LED backlight drivers.

The ADP5350 LED drivers can support a wide range of LED backlight configurations, either multiple LEDs in parallel or in series.

The ADP5350 low dropout (LDO) regulators are optimized to operate at low shutdown current and quiescent current to extend battery life. The device also operates as a load switch that can be fully turned off or on.

The I²C-compatible interface enables the programmability of all parameters, including status bit readback for operation monitoring and safety control.

The ADP5350 operates over the −40°C to +125°C junction temperature range and is available in a 32-lead, 5 mm × 5 mm LFCSP package and a 32-ball, 3 mm × 3 mm WLCSP package.

Applications

• Rechargeable Li-Ion and Li-Ion polymer battery-powered devices
• Portable consumer devices
• Portable medical devices
• Portable instrumentation devices
• Wearable devices

The universal serial bus (USB) is rapidly becoming the standard interface for most PC peripherals. It is displacing RS-232 and the parallel printer port because of superior speed, flexibility, and support of device hot swap. There has been a strong desire on the part of industrial and medical equipment manufacturers to use the bus as well, but adoption has been slow because there has not been a good way to provide the isolation required for connections to machines that control dangerous voltages or low leakage defibrillation proof connections in medical applications.

The ADuM4160 is designed primarily as an isolation element for a peripheral USB device. However, there are occasions when it is useful to isolate a host device. Several issues must be addressed to use the ADuM4160 for this application. Whereas the buffers on the upstream and downstream sides of the ADuM4160 are the same and capable of driving a USB cable, the downstream buffers must be capable of adjusting speed to a full or low speed peripheral that is connected to it.

Unlike the case of building a dedicated peripheral interface where the speed is known and not changed, host applications must adapt. The ADuM4160 is intended to be hardwired to a single speed via pins; therefore, it works when the peripheral plugged into its downstream side is the correct speed, but it fails when the wrong speed peripheral is attached. The best way to address this is to combine the ADuM4160 with a hub controller.

The upstream side of a hub controller can be thought of as a standard fixed speed peripheral port that can be easily isolated with the ADuM4160, whereas the speed of the downstream ports is handled by the hub controller. The hub controller converts peripherals of different speeds to match the upstream port speed. The circuit shown in Figure 1 shows how a two-port hub chip can be used to isolate two downstream host ports in a design that can be made fully compliant with the USB specification.

The ADuM4160 provides an inexpensive and easy to implement isolation buffer for medical and industrial peripherals. The challenge that must be met is to use this to create a fully com-pliant host port by pairing the ADuM4160 with a hub chip. As with isolating any peripheral device, the services that the ADuM4160 and hub provide are as follows:

1. Directly isolates, in the upstream, the USB D+ and D− lines of a hub chip, allowing the hub to manage the downstream host port activity.
2. Implements an automatic scheme for data flow of control that does not require external control lines.
3. Provides medical grade isolation.
4. Allows creation of one or more host ports that meet the USB-IF certification standards.
5. Supports full speed signaling rates.
6. Supports flexible power configurations.

The goal of the application circuit is to isolate a hub as if it were a full speed peripheral device. The hub or host function requires that 2.5 W of power be available to each downstream port. Power to run the downstream side of the isolator and power the hub and ports is provided as part of the solution. The application circuit is typical of many medical and industrial applications.

The universal serial bus (USB) is rapidly becoming the standard interface for most PC peripherals. It is displacing RS-232 and the parallel printer port because of superior speed, flexibility, and support of device hot swap. There has been a strong desire on the part of industrial and medical equipment manufacturers to use this bus as well, but adoption has been slow because there has not been a good way to provide the isolation required for connections to machines that control dangerous voltages or low leakage defibrillation proof connections in medical applications.

The ADuM4160 provides an inexpensive and easy to implement isolation buffer for medical and industrial peripherals. The challenges that need to be met are:

1. Isolate directly in the USB D+ and D− lines allowing the use of existing USB infrastructure in microprocessors.
2. Implement an automatic scheme for data flow of control that does not require external control lines.
3. Provide medical grade isolation.
4. Allow a complete peripheral to meet the USB-IF certifi-cation standards.
5. Support full speed (12 Mbps) and low speed (1.5 Mbps) signaling rates.
6. Support flexible power configurations.

The circuit shown in Figure 1 isolates a peripheral device that already supports a USB interface. Because the peripheral is not explicitly defined in this circuit, power to run the secondary side of the isolator has been provided as part of the solution. If the circuit is built onto the PCB of a peripheral design, power could be sourced from the peripheral’s off line supply, a battery, or the USB cable bus power, depending on the needs of the application.

The application circuit shown is typical of many medical and industrial applications.

The universal serial bus (USB) is rapidly becoming the standard interface for most PC peripherals. It is displacing RS-232 and the parallel printer port because of superior speed flexibility and support of device hot swap. There has been a strong desire on the part of industrial and medical equipment manufacturers to use the bus as well, but adoption has been slow because there has not been a good way to provide the isolation required for connections to machines that control dangerous voltages or low leakage defibrillation proof connections in medical applications.

The ADuM4160 is designed primarily as an isolation element for a peripheral USB device. However, there are occasions when it is useful to create an isolated cable function. Several issues must be addressed to use the ADuM4160 for this application. Whereas the buffers on the upstream and downstream sides of the ADuM4160 are the same and capable of driving a USB cable, the downstream buffers must be capable of adjusting speed to a full or low speed peripheral that is connected to it. The upstream connection must act like a peripheral, and the downstream connection must behave like a host.

Unlike the case of building a dedicated peripheral interface where the speed is known and not changed, host applications must adapt to detect whether a low or full speed device has been connected. The ADuM4160 is intended to be hardwired to a single speed via pins; therefore, it works when the peripheral plugged into its downstream side is the correct speed, but it fails when the wrong speed peripheral is attached. The best way to address this is to combine the ADuM4160 with a hub controller.

The upstream side of a hub controller can be thought of as a standard fixed speed peripheral port that can be easily isolated with the ADuM4160, whereas the downstream ports are all handled by the hub controller. However, in many cases, while it is not certifiable as fully USB compliant, a single speed cable is acceptable from a practical standpoint, especially if custom connectors are used so that it cannot be confused with a compliant device. The hub chip can be eliminated, and the design becomes very small and simple.

The ADuM4160 provides an inexpensive and easy way to implement an isolation buffer for medical and industrial peripherals. The challenge that must be met is to use this to create a bus-powered cable isolator by pairing the ADuM4160 with a small isolated dc-to-dc converter such as the ADuM5000. As with isolating any device, the services that the ADuM4160 provides are as follows:

1. Directly isolates, in the upstream, the USB D+ and D− lines of a cable.
2. Implements an automatic scheme for data flow of control that does not require external control lines.
3. Provides medical grade isolation.
4. Supports full speed or low speed signaling rates.
5. Supports isolated power delivery through the cable.

The goal of the application circuit shown in Figure 1 is to isolate a peripheral device that already implements a USB interface. It is not possible to make a fully compliant bus-powered cable because there are no 100% efficient power converters to transfer the bus voltage across the barrier. In addition, the quiescent current of the converter does not comply with the standby current requirements of the USB standard. This is all in addition to the speed detection limitations of the ADuM4160. What can be achieved is a fixed speed or switch-controlled speed cable that can supply a modest power to the downstream peripheral. However, it is a custom application that is not completely compliant with the USB standard.

The circuit shown in Figure 1 connects an ADAU1701 codec with an integrated SigmaDSP^® core to an SSM2306 2 W stereo Class-D amplifier and an ADP3336 low dropout regulator. The ADAU1701 has two ADCs and four DACs; therefore, it can process a stereo audio signal and output discretely processed signals to both a line-level output and an amplified output. This allows the line and amplified outputs to be processed in the SigmaDSP core with different signal processing, such as custom EQ, compressors tailored to the clip level of the specific output, or spatialization effects tuned to the specific speaker configurations. The ADP3336 generates the 3.3 V supply for the ADAU1701. The SSM2306 is a stereo 2 W Class-D amplifier with ultralow idle current and high efficiency. The amplifier does not require bulky external inductors, but it does require minimal external components and has a small system footprint. The amplifier’s voltage is not supplied from the regulator but rather directly from the 5 V system supply. This system can provide an audio signal processing path output to a low power efficient amplifier for systems such as radios, multimedia docks, or PC speakers.