Part Number : AAT1171
Function : Voltage-Scaling Step-Down Converter
Manufactures : AAT
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Description :
600mA Voltage-Scaling Step-Down Converter for RF Power Amplifiers with Bypass Switch General Description The AAT1171 SwitchReg, a member of AnalogicTech’s Total Power Management IC™ (TPMIC™) product family, has been specifically designed to dynamically control the operating voltage of a WCDMA or CDMA power amplifier inside single lithium-ion battery-powered systems. The AAT1171 outputs a voltage between 0.6V and 3.6V, thereby optimizing the amplifier efficiency at both low and high transmit levels. AAT1171 Features SwitchReg™ The AAT1171 output voltage is controlled via an • analog signal from the baseband processor. It can • deliver 600mA of continuous load current while • maintaining a low 45µA of no load quiescent current. • The 2MHz switching frequency minimizes the size of • external components while keeping switching losses • low. A low resistance MOSFET, typically 230mΩ, • provides a low dropout voltage as the battery input voltage approaches the programmed output voltage and the converter runs at 100% duty cycle. To further improve system efficiency, an 85mΩ bypass MOSFET transistor is also included to allow the PA Applications to be powered directly from the battery. • WCDMA or CDMA PA in Cellular Phones, The AAT1171 feedback and control method gives Smartphones, Feature Phones, etc. excellent load regulation and transient response • Express Card while maintaining small external components. The • PCMCIA Data Cards output voltage responds in less than 30µs. The converter can be synchronized to an external system clock, forced to operate in Light Load (LL) mode for highest efficiency at light loads, or in Pulse Width Modulation (PWM) mode for low noise operation. The AAT1171 is available in a Pb-free, space-saving TDFN33-12 package and is rated over the -40°C to +85°C temperature range. VIN Range: 2.7V to 5.5V Variable Output Voltage: 0.6V to 3.6V 600mA Output Current DAC Input: 0.2V to 1.2V High Output Accuracy: ±3% 45µA No Load Quiescent Current Internal Soft Start Limits Startup Current and Output Voltage Overshoot Synchronizable to External 19.8MHz System Clock Over-Temperature and Current Limit Protection Integrated 85mΩ Bypass MOSFET 2MHz Operation PWM/LL Control with Override Fast 150µs Start-Up 3x3mm 12-Pin TDFN Package Temperature Range: -40°C to +85°C Typical Application VIN 2.2µH 0.6V – 3.6V 10µF VCC AAT1171 BYPASS LX – MODE/SYNC EN DAC GNDx2 VOUT 4.7µF VCC2 VCONT VREF VCC2 PA DAC Baseband Processor TX RX 1171.2006.06.1.0 1 600mA Voltage-Scaling Step-Down Converter for RF Power Amplifiers with Bypass Switch Pin Descriptions Pin # 1 2, 3 AAT1171 Symbol N/C VOUT Function Not connected. Feedback input pin. This pin is connected to the converter output. It is used to complete the control loop, regulating the output voltage to the desired value. When in bypass mode, a low resistance MOSFET is connected between this pin […]
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