LTC1957-1/LTC1957-2 Single/Dual Band RF Power Controllers with 40dB Dynamic Range FEATURES DESCRIPTIO n Dual Band RF Power Amplifier Control (LTC1957-2) The LTC 1957-2 is a dual band RF power controller for n Internal Schottky Diode Detector with Improved power amplifiers operating in the 850MHz to 2GHz range. Dynamic Range vs the LTC1757A The input voltage range is optimized for operation from n Wide Input Frequency Range: 850MHz to 2GHz a single lithium-ion cell or 3 NiMH. Several functions n Autozero Loop Cancels Offset Errors and required for RF power control and protection are inte- Temperature Dependent Offsets grated in one small 10-pin MSOP package, thereby n Wide V Range: 2.7V to 6V minimizing PCB area. IN n Allows Direct Connection to Battery The LTC1957-1 is a single output RF power controller n RF Output Power Set by External DAC that is identical in performance to the LTC1957-2 except n Fast Acquire After Transmit Enable that one output (V ) is provided. The LTC1957-1 can PCA n Internal Frequency Compensation be used to drive a single RF or dual channel module with n Rail-to-Rail Power Control Outputs integral multiplexer. This part is available in an 8-pin n Power Control Signal Overvoltage Protection MSOP package. n Low Operating Current: 1mA n RF power is controlled by driving the RF amplifier power Very Low Shutdown Current: <1m A n control pins and sensing the resultant RF output power Available in a 8-Pin MSOP Package (LTC1957-1) via a directional coupler. The RF sense voltage is peak and 10-Pin MSOP (LTC1957-2) n detected using an on-chip Schottky diode. This detected Pin Compatible with the LTC1757A-X n voltage is compared to the DAC voltage at the PCTL pin Improved Start Voltage Accuracy and Range n to control the output power. The RF power amplifier is Improved PCTL Input Filtering protected against high supply current and high power U control pin voltages. APPLICATIO S Internal and external offsets are cancelled over tempera- n Single and Dual Band GSM/GPRS Cellular Telephones ture by an autozero control loop, allowing accurate low n PCS Devices power programming. The shutdown feature disables the n Wireless Data Modems part and reduces the supply current to <1m A. n U.S. TDMA Cellular Phones , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO LTC1957-2 Dual Band Cellular Telephone Transmitter 68 LTC1957-2 33pF V IN 1 10 V V IN CC 2 9 DIRECTIONAL Li-Ion RF V PCA COUPLER DIPLEXER 3 8 SHDN SHDN V PCB 900MHz RF PA 4 7 BSEL BSEL TXEN TXEN 5 6 GND PCTL 50 DAC 1.8GHz/1.9GHz RF PA 1957 TA01 1 U ULTC1957-1/LTC1957-2 ABSOLUTE AXI U RATI GS (Note 1) V to GND............................................... 0.3V to 6.5V I , 25% Duty Cycle ...................................... 20mA IN VPCA/B V , V Voltage ..................................... 0.3V to 3V Operating Temperature Range (Note 2) . 30 C to 85 C PCA PCB PCTL Voltage ............................... 0.3V to (V + 0.3V) Storage Temperature Range ................ 65 C to 150 C IN RF Voltage ........................................ (V 2.2V) to 7V Maximum Junction Temperature ........................ 125 C IN I , Continuous ....................................................... 1A Lead Temperature (Soldering, 10 sec)................ 300 C VCC I , 12.5% Duty Cycle.......................................... 2.5A VCC SHDN, TXEN, BSEL Voltage to GND ............................ 0.3V to (V + 0.3V) IN UUW PACKAGE/ORDER I FOR ATIO ORDER PART ORDER PART NUMBER NUMBER TOP VIEW TOP VIEW V 1 10 V IN CC V 1 8 V IN CC RF 2 9 V PCA LTC1957-1EMS8 LTC1957-2EMS RF 2 7 V PCA SHDN 3 8 V PCB SHDN 3 6 TXEN BSEL 4 7 TXEN 5 PCTL GND 4 GND 5 6 PCTL MS8 PACKAGE MS10 PACKAGE MS8 PART MARKING MS10 PART MARKING 8-LEAD PLASTIC MSOP 10-LEAD PLASTIC MSOP T = 125 C, q = 160 C/W T = 125 C, q = 160 C/W JMAX JA JMAX JA LTRH LTRJ Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. V = 3.6V, SHDN = TXEN = HI, unless otherwise noted. A IN PARAMETER CONDITIONS MIN TYP MAX UNITS V Operating Voltage l 2.7 6 V IN I Shutdown Current SHDN = LO, TXEN = LO, BSEL = LO l 1 m A VIN I Autozero Current SHDN = HI, TXEN = LO l 1 1.6 mA VIN I Operating Current SHDN = HI, TXEN = HI, I = I = 0mA, V = HI 1.1 1.7 mA VIN VPCA VPCB PCA/B I Current Limit 2.2 A VCC V to V Resistance SHDN = LO, TXEN = LO 90 150 mW IN CC V V TXEN = HI, Open Loop, PCTL = 100mV l 0 0.1 V PCA/B OL V Dropout Voltage I = 5.5mA, V = 2.7V l V 0.28 V PCA/B LOAD IN IN V Voltage Clamp R = 400W , PCTL = 2V, External Gain = 0.417 l 2.7 2.85 3.0 V PCA/B LOAD V Output Current V = 2.4V, V = 2.7V l 5.5 9 mA PCA/B PCA/B IN V = 2.6V, V = 3V l 6.0 10 mA PCA/B IN V Enable Time V = 2V Step, C = 100pF (Note 5) l 440 650 ns PCA/B PCTL LOAD V Bandwidth C = 100pF, R = 400W (Note 8) l 280 370 500 kHz PCA/B LOAD LOAD V Load Capacitance (Note 6) 100 pF PCA/B V Slew Rate V = 2V Step, C = 100pF (Note 3) l 1.2 2.2 V/m s PCA/B PCTL LOAD V Droop V = 2.7V, V = 2V Step 1 m V/ms PCA/B IN PCTL V TXEN Start Voltage Open Loop, TXEN Low to High, C = 100pF (Note 9) 500 600 700 mV PCA/B LOAD 2 U WWW