Texas Instruments' TPS63020 device provides a power supply solution for products powered by either a two- or three-cell alkaline, NiCd, or NiMH battery or a one-cell Li-Ion or Li-polymer battery. Output currents can go as high as 3 A while using a single-cell Li-Ion or Li-Polymer battery and discharge it down to 2.5 V or lower. This buck-boost converter is based on a fixed frequency, pulse-width-modulation (PWM) controller using synchronous rectification to obtain maximum efficiency. At low load currents, the converter enters a Power Save mode to maintain high efficiency over a wide load current range. The Power Save mode can be disabled, forcing the converter to operate at a fixed switching frequency. The maximum average current in the switches is limited to a typical value of 4 A. The output voltage is programmable using an external resistor divider or is fixed internally on the chip. This converter can be disabled to minimize battery drain. During shutdown, the load is disconnected from the battery. The device is packaged in a 14-pin QFN PowerPAD™ package measuring 3 mm × 4 mm (DSJ).
The average inductor current is limited internally in the IC. At nominal operating conditions, the current limit is constant. If the input power source becomes weak – such as when batteries are almost discharged and increase the output impedance or there is an overload condition due to an additional heavy pulse load connected to the battery – the supply voltage at VIN may drop below 2.3 V. If this occurs, the TPS63020 automatically reduces the current limit
Limiting the input current prevents the battery from going into hard undervoltage lockout and it gives the battery time to recover and return to higher voltage levels. If recovery is not possible, the device will slowly go into an undervoltage lockout condition.
When there is an excess of current demanded by the system, the dynamic input current limit is activated and the Power Good signal goes low. The Power Good signal is triggered at the earliest possible time, notifying the rest of the system of a potential unregulated output voltage. If the overload condition is only sporadic and goes away, the battery voltage recovers and the TPS63020 returns to normal operating conditions. The dynamic input current limit is then disabled and the Smart Power Good goes high again.
If the temperature of the device increases above the recommended temperature, the Smart Power Good signal will also go low and will notify the rest of the system of a potential overtemperature shutdown. Under these conditions, the input current limit is activated, reducing the current flow through the device and allowing the temperature to return to lower levels. If the temperature continues to increase, the device will eventually go in shutdown mode, after the over temperature protection has been activated.
Smart Power Good and Dynamic Input Current Limit give the TPS63020 a 'touch' of intelligence, which eases system design. These features, together with high efficiency (up to 96%) and a small total solution size of less than 100 mm2, make the TPS63020 a great device for designers who want the latest features available in the market in battery driven applications.
- Up to 96% efficiency
- 3 A output current at 3.3 V in step down mode
- (VIN = 3.6 V to 5.5 V)
- More than 2 A Output Current at 3.3 V in Boost Mode (VIN > 2.5 V)
- Automatic transition between step down and boost mode
- Dynamic input current limit
- Device quiescent current less than 50 µA
- Input voltage range: 1.8 V to 5.5 V
- Fixed and adjustable output voltage options from 1.2 V to 5.5 V
- Power save mode for improved efficiency at low output power
- Forced fixed frequency operation at 2.4 MHz and synchronization possible
- Smart Power Good Output
- Load disconnect during shutdown
- Overtemperature protection
- Overvoltage protection
- Available in a 3 mm × 4 mm, QFN-14 package
- All two-cell and three-cell alkaline, NiCd or NiMH or single-cell Li battery powered products
- Ultra mobile PC's and mobile internet devices
- Digital media players
- DSC's and camcorders
- Cellular phones and smartphones
- Personal medical products
- Industrial metering equipment
- High power LED's