Innovative Solutions for Li-ion Battery-Powered Applications

Applications powered by Li-ion batteries are hugely popular in the market today. Whether it be a piece of wearable tech, a new IoT device or a tablet computer, Li-Ion batteries provide the power for many of the products we use every day.

The system requirements and size of battery will vary, but the principals of any Li-Ion design remain the same. Designers will always need small, efficient solutions that can operate with low power consumption to maximise battery life.

Torex offers a variety of different power management solutions for single cell Li-Ion based systems, solutions for when a Li-ion battery is used to power a simple system and also solutions for when a Li-ion Battery is used to power a system with multiple higher current rails. This article looks at both cases and shows how Torex’s low power IC can be implemented to provide solutions for both.

Using a Single Li-ion Battery to Power a Simple System

Key System Requirements:

1. Implement discharge prevention during shipment and have an effective countermeasure for a system freeze.
2. Ensure highest efficiency with ultra-low power consumption for the main power circuitry.
3. Must have low noise output from the LDO for the RF and sensor rails.

Torex offers several solutions for such applications, solutions that meet these requirements, and below we illustrate a typical power architecture and show how our products can be used:

Battery Charger IC

(1) The XC6803 & XC6808 are Constant-Voltage (CV) and Constant-Current (CC) type charging IC for linear charging of single-cell Li-ion and Li-polymer batteries. Operating voltage is between 4.5 V~6.0 V and with the XC6803, CV is 4.2 V and CC is set externally within a range of 40~280mA. With the XC6808, users can select one of three different Charge Voltage thresholds (4.20 V, 4.35 V or 4.40 V) and the Charge Current is adjusted from 5mA to 40mA with an external resistor.

Push Button Load Switch with built-in Ship-Mode Function

(2) The XC6194 is a simple solution for disconnecting the system during shipment (ship-mode).?It can also be used to RESET the whole system in the event of a software freeze event. Operating voltage is between 1.8 V~6.0 V and quiescent current is only 0.13μA. Four turn-on & turn-off delay time options are available, and the IC is in a space saving USP-8B06 package measuring only 2.0 x 2.0 x 0.33mm!

Ultra-Low Power/Low EMI Buck DC/DC & Micro DC/DC for MCU

(3) Ultra-low quiescent current DC/DC are ideal for this application.?Our XCL232 and XC9276 offer very low Iq (200nA typ.) and the XC9276 has an additional VSET function which allows the designer to select a lower VOUT for when the MCU is sleeping. The XCL232 is a Micro DC/DC so the inductor is integrated, perfect for space constrained applications. Both the XC9276 & XCL232 operate between 1.8 V~6.0 V and support output currents of up to 150mA. Output voltages between 0.5 V~3.6 V are selectable and as mentioned, with the XC9276, the output voltage select function (VSET) enables two separate voltages to be pre-selected from within this range.

To further reduce the EMI our XCL202 Micro DC/DC provides a compact solution, with a lower 1.2MHz switching frequency, which is ideal for noise sensitive supply rails required for sensors and RF circuits. The XCL202 operates to 6.0 V and supports up to 400mA output current. Output voltage is fixed between 0.8 V~4.0 V.

Green Operation LDO for RF/Sensor

(4) The XC6241’s Green Operation (GO) circuit automatically reduces quiescent current at low output loads down to only 0.xn--6a-99b (typ, whilst offering extremely fast ripple rejection (60dB @ 1kHz) and low dropout voltage (130mV @ 100mA) in high-speed mode (HS). The XC6241 operates between 1.6 V~6.0 V and supports up to 150mA output current. The output range is 1.2 V~5.0 V which can be selected in 50 mV increments.

With this GO LDO, you can extend the life of an internal battery to in excess of 10 years. Perfect for small devices where the battery drain can be decreased and therefore potentially reducing the size of the battery or extending its life.

Ultra-Low Power RESET IC

(5) The XC6136 series is an ultra-low power voltage detector that can detect voltages down to 1.2V. Operating voltage is from 1.1 V ~ 6.0 V and with a quiescent current of only 88nA, the XC6136 can extend the operating time of devices with small batteries such as IoT devices, wearable devices, and smart meters. Both CMOS & Open Drain are available and the XC6136 has RESETB (Active Low) & RESET (Active High) output logic options.

Using a Single Li-ion Battery to Power a System with Multiple Higher Current Rails

Key System Requirements:

1. Ensure highest efficiency with ultra-low power consumption for the main power circuitry.
2. Minimise EMI with careful selection of small highly integrated solutions.
3. Allow for automatic switching between the main 5V supply and the Li-ion battery when 5V removed.
4. Implement discharge prevention during shipment and have an effective countermeasure for a system freeze.

Battery Charger IC

(6) The XC6804 is a Constant-Voltage (CV) and Constant-Current (CC) type charging IC for linear charging of single-cell Li-ion and Li-polymer batteries. Operating voltage is between 4.5 V~6.0 V, CV is 4.2 V and CC is set externally within a range of 200~800mA. Available in a small USP-6EL package measuring 2.0 x 1.8 x 0.4mm.

Load Switch with Ideal Diode Function

(7) The circuit above automatically switches between the main 5V input rail and the Li battery output using the XC8110/11 ideal diode in an OR circuit configuration. The XC8110/11 is perfect for OR circuits because of its low VF and 0 μA VIN Iq when Reverse biased. The XC8110 supports an output current of 500mA whereas the XC8111 can support up to 1A. Both versions have a quiescent current of only 3.6μA and a stand-by current of 0.65μA. The series is IEC62368-1 Certified.

Adding an additional Nch FET will implement a shipping-mode function, whereby the system can be disconnected from the battery when the product is shipped from the factory to the end user.?The system can be reconnected when the user pushes the power button.

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Buck DC/DC & Micro DC/DC for MCU / Memory / FPGA at Point of Load (POL)

(8) Stable operation with small size and low EMI can be realised by placing a Micro DC/DC with integrated coil close to the POL. Torex has a range of step-down Micro DC/DC to support different levels of load current from 400mA with the XCL201/XCL202, 600mA with the XCL205/XCL206 and 2A with the XCL211/XCL212. All operate to 6.0 V and are space saving solutions because the inductor is integrated.

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Push Button Reboot Controller

(9) The XC6190 is a low power push button reboot IC that can reboot the system by pressing and holding an external switch as a countermeasure for system freeze. The switch can also be shared with the MCU for other functions. The XC6190 operates within a range of 1.75 V~6.0 V. With the XC6190A the reboot delay time (TDL) can be set as desired by changing the external resistance RT within the range 5s to 20s. The XC6190B has the TDL fixed internally with a choice of two settings. When the TS pin is set to “H” level, the delay time is 12.5s. When the TS pin is set to “L” level, the delay time is 7.5s.

Further Reading:

This article is also available on our website and is accessible using the link below.?From the webpage you can link to all the featured products to get more details and download data sheets:

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