TPS60204DGSR

The TPS6020x step-up, regulated charge pumps generate a 3.3–V ±4% output voltage from a 1.8-V to 3.6-V input voltage. The devices are typically powered by two Alkaline, NiCd, or NiMH battery cells and operate down to a minimum supply voltage of 1.6 V. Continuous output current is a minimum of 100 mA from a 2-V input. Only four external capacitors are needed to build a complete low-ripple dc/dc converter. The push-pull operating mode of two single-ended charge pumps assures the low output voltage ripple, as current is continuously transferred to the output. The devices operate in the newly developed LinSkip mode. In this operating mode, the device switches seamlessly from the power saving pulse-skip mode at light loads to the low-noise constant-frequency, linear-regulation mode once the output current exceeds the LinSkip threshold of about 7 mA. Even in pulse-skip mode, the output ripple is maintained at a very low level because the output resistance of the charge pump is still regulated. Three operating modes can be programmed using the EN pin. EN = low disables the device, shuts down all internal circuits, and disconnects the output from the input. EN = high enables the device and programs it to run from the internal oscillator. The devices operate synchronized to an external clock signal if EN is clocked; thus, switching harmonics can be controlled and minimized. The devices include a low-battery detector that issues a warning if the battery voltage drops below a user-defined threshold voltage, or a power-good detector that goes active when the output voltage reaches about 90% of its nominal value. Device options with either a low-battery or power good detector are available. This dc/dc converter requires no inductors, therefore, EMI of the system is reduced to a minimum. It is available in the small 10-pin MSOP package (DGS). The TPS6020x charge pumps provide a regulated 3.3-V output from a 1.8-V to 3.6-V input. They deliver up to 100 mA load current while maintaining the output at 3.3 V ±4%. Designed specifically for space critical battery powered applications, the complete converter requires only four external capacitors. The device is using the push-pull topology to achieve lowest output voltage ripple. The converter is also optimized for smallest board space. It makes use of small sized capacitors, with the highest output current rating per output capacitance and package size. The TPS6020x circuits consist of an oscillator, a 1.18-V voltage reference, an internal resistive feedback circuit, an error amplifier, two charge pump power stages with high current MOSFET switches, a shutdown/start-up circuit, and a control circuit. The two single-ended charge pump power stages operate in the so-called push-pull operating mode, i.e., they operate with a 180° phase shift. Each single-ended charge pump transfers charge into its transfer capacitor (C1 or C2) in one half of the period. During the other half of the period (transfer phase), the transfer capacitor is placed in series with the input to transfer its charge to C0. While one single-ended charge pump is in the charge phase, the other one is in the transfer phase. This operation assures an almost constant output current which ensures a low output ripple. If the clock were to run continuously, this process would eventually generate an output voltage equal to two times the input voltage (hence the name voltage doubler). In order to provide a regulated fixed output voltage of 3.3 V, the TPS6020x devices use either pulse-skip or constant-frequency linear-regulation control mode. The mode is automatically selected based on the output current. If the load current is below the LinSkip current threshold, it switches into the power-saving pulse-skip mode to boost efficiency at low output power.

Applications

• Replaces DC/DC Converters With Inductors in Battery Powered Applications
• Two Battery Cells to 3.3-V Conversion
• MP3 Portable Audio Players
• Battery-Powered Microprocessor Systems
• Backup-Battery Boost Converters
• PDA’s, Organizers, and Cordless Phones
• Handheld Instrumentation
• Glucose Meters and Other Medical Instruments

Key features

• Regulated 3.3-V Output Voltage With up to 100-mA Output Current From a 1.8-V to 3.6-V Input Voltage
• Less Than 5-mV(PP) Output Voltage Ripple Achieved With Push-Pull Topology
• Integrated Low-Battery and Power-Good Detector
• Switching Frequency Can Be Synchronized to External Clock Signal
• Extends Battery Usage With up to 90% Efficiency and 35-μA Quiescent Supply Current
• Easy-to-Design, Low Cost, Low EMI Power Supply Since No Inductors Are Used
• 0.05-μA Shutdown Current, Battery is Isolated From Load in Shutdown Mode
• Compact Converter Solution in UltraSmall 10-pin MSOP With Only Four External Capacitors Required
• Evaluation Module Available (TPS60200EVM-145)