For the consumer handheld devices, the historic two AA (alkaline or Ni-MH battery) power is the most commonly used Panasonic Nv-gs11 Battery solutions, especially in the GPS navigation devices, digital cameras and MP3 players. AA batteries easy to buy, low cost and high power density. In these portable devices, many have adopted the plug-in AC adapter, and provides a USB bus (for data transfer) as a supplement battery power. USB bus power can also be used. The question is how these three different power supply (two AA batteries, AC adapter and USB) to seamlessly switch between. LTC3456 is a suitable solution.
LTC3456 is a complete system power supply IC, AC adapter can be achieved, USB and two AA Dell Lite-On PA-1131-02D Adapter batteries power flux between the seamless management and comply with USB power standards, all of these functions are integrated in a 4mm x 4mm QFN within the package (Figure 1). The device generates two separate power rails: a 3.3V (fixed) main power supply and a 1.8V (adjustable) core power supply. In addition, LTC3456 also includes a fully functional USB power manager, used to store a hot plug power supply (Hot Swap) output and is suitable for low-battery comparator or LDO controller gain independent parts. The device also generates an always-running VMAX output, the output is suitable for such real-time clock for the shutdown period also necessary even in the working state of the key components in power transmission.
LTC3456 contains four high efficiency up to 92% of the 1MHz fixed-frequency switching regulators. Figure 2 shows a typical LTC3456 application. Used in portable applications, most processors require dual-supply voltage. The voltage can be 3.3V (for I / O circuits) and 1.5V or 1.8V (for the processor core). In addition, the processor may also require the power to start in a specific order to prevent blocking or error processor start. Typically, the core power to the I / O power supply before the rise.
Figure 2 is based LTC3456 complete power solutions, including a 1.8V output (for the processor core), a 3.3V output (for I / O), a hot-plug power supply 3.3V (used to store plug-in) and a VMAX output (for RTC)
LTC3456 has a main output for the kernel and built-in power sequencing function. On power, VINT output (a fixed 3.3V power supply) on the implementation of the first power-on operation. It is responsible for most of the internal circuitry. Response to the external load on the output size is limited. Adjustable from 0.8V to 1.8V core output then increased, followed by VMAIN output. VMAIN output (a fixed 3.3V power supply) into the regulation state in the kernel output after delay 0.8ms (typical) power. VMAIN output by the VINT output through an internal 0.4Ω (typ) PMOS switch and produce, and can be used to I / O circuitry. 0.8ms delay processor power in the external circuit to complete the system clock on the stability and load internal registers provide a sufficient time.
LTC3456 generates an adjustable 0.8V to 1.8V core output, the output for the new low-voltage processors (ARM, etc.) power supply. LTC3456 output control circuit allows the kernel to work 100% duty cycle. When the kernel output from the ACER TravelMate 527 Laptop AC Adapter batteries to power, it provides low dropout operation, extending battery life. When the battery-powered, the main converter and core converters offer a burst mode operation (MODE pin can be used to select), so in light load conditions to achieve high efficiency. In the case of battery-powered, the kernel has more than 92% converter efficiency. When the USB / wall power supply to power, the Burst Mode operation is disabled. When powered from the USB to the main converter up to 90% efficiency.
LTC3456 suitable for flash memory card with a built-in hot swap power supply output. The hot-plug output with short circuit and reverse voltage isolation. It allows plug-in system stored on the hot plug. It has a suitable power supply to the flash memory card, 120mA (typical) Built-in current limit.
LTC3456 provides the core for the main output and output short circuit protection. It also provides all of the output (VMAX output excluded) provides output disconnect. In shutdown mode, the core output, main output, and outputs are discharged to ground hot. In VBATT, VINT, VEXT and USB voltage, VMAX output is the highest. The output can be used to provide the maximum output current of 1mA. Even if the IC is in shutdown mode in the case, VMAX output will remain running, and thus suitable for real-time clock to the critical system components such as power supply.
Table 1 LTC3456 PowerPath summary of the work patterns and characteristics
PowerPath control
LTC3456 includes a proprietary PowerPath control circuitry to achieve seamless handover between system power (from two AA NOKIA 9210 PDA battery to USB / wall power, or vice versa). Figure 3 shows a simplified block diagram of an internal power supply path. AC adapter and the USB bus through the VEXT pin to the switching regulator power supply. LTC3456 includes a full-featured USB Power Manager to take advantage of USBHP and SUSPEND pin to control the state of the power flux from the USB pin. USB pin current is flowing through the precise limit of 100mA or 500mA (depending USBHP pin on the state). By SUSPEND pin pulled high to disable all USB functions.
When must raise two AA Panasonic Lumix Dmc-fx30 Battery voltage (1.8 V to 3.2 V) to generate 3.3 V output, and USB/the wall must be the power (4 V to 5.5 V) to produce the same antihypertensive operation voltage, DC-DC changeover will be a particularly challenging job. LTC3456 through the BOOST and BUCK2 converter finished this task. This is a generated 3.3 V power rail the most efficient way. When the battery or USB/communication from adapter to generate 3.3 V output, LTC3456 realizes the higher than 90% efficiency. The kernel output (1.8 V) is through the BUCK1 (by USB/the wall power to power supply) and BUCK3 (by the Canon Eos-300d Battery to power supply) converter to generate. The unique LTC3456 topological structure of a single inductor available to generate 1.8 V power rail, which saves the cost and space. When from the battery to generate 1.8 V output, it achieved more than 92% efficiency. Table 1 LTC3456 lists the different work model.
Portable devices need to realize from battery power to USB or the wall seamless switching power supply (and vice versa) to ensure the smooth operation of the system. For example, a user is a USB cable to connect the portable MP3 music played on board. If the USB cable is suddenly pulled off from the equipment, the user should be able to continue to listen to music, and won't aware of any interruption phenomenon. LTC3456 through the realization of switching power supply system and make the desire of seamless become possible. When SUSPEND pin was low electricity from PingLa to high electricity at ordinary times, not with USB power supply. The main output and the kernel when switching output in both showed less than? % of total deviation, and thus realizes the processor core and periphery circuit to the seamless switch.
Portable devices need to realize from battery power to USB or the wall seamless switching power supply (and vice versa) to ensure the smooth operation of the system. For example, a user is a USB cable to connect the portable MP3 music played on board. If the USB cable is suddenly pulled off from the equipment, the user should be able to continue to listen to music, and won't aware of any interruption phenomenon. LTC3456 through the realization of switching power supply system and make the desire of seamless become possible. When SUSPEND pin was low electricity from PingLa to high electricity at ordinary times, not with USB power supply. The main output and the kernel when switching output in both showed less than? % of total deviation, and thus realizes the processor core and periphery circuit to the seamless switch.
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source from blog: http://batteru.blogspot.com/
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