MAX881R 19-1372 Rev 2 1/04 Low-Noise Bias Supply in MAX with Power-OK for GaAsFET PA General Description The MAX881R low-noise, inverting power supply is Features designed for biasing GaAsFET power amplifiers in portable wireless applications. This device is a charge- Small MAX Package pump inverter followed by a negative linear regulator. 1mVp-p Output Voltage Ripple and Noise The input voltage range is 2.5V to 5.5V. The output is Power-OK Signal to Control GaAsFET Drain preset at -2.0V or can be set, using two resistors, to any voltage from -0.5V to (-V + 0.6V). It can deliver up to IN Switch 4mA. The internal linear regulator also filters the output 0.05A Logic-Controlled Shutdown to 1mVp-p ripple and noise. 1ms Guaranteed Startup Other features include a power-OK (POK) output that sig- nals when the negative voltage is within 7.5% of its set 2.5V to 5.5V Input point. It protects the GaAsFET by not allowing power to -0.5V to (-V + 0.6V) Output at up to 4mA IN be applied to the GaAsFETs drain until it is properly biased. The signal can be routed either to a microcon- Operates with One 4.7F and Three 0.22F troller or directly to a switch at the GaAsFET drain. The Capacitors (no inductors needed) MAX881R is available in a 10-pin MAX package. Applications Ordering Information Cell Phones Wireless Modems PART TEMP RANGE PIN-PACKAGE PCS Phones Two-Way Pagers MAX881REUB -40C to +85C 10 MAX PHS Phones Mobile Radios Wireless Handsets Wireless Computers Pin Configuration Typical Operating Circuit OUTPUT TOP VIEW -2V (OR ADJ) INPUT 4mA, 1mVp-p 2.5V TO 5.5V RIPPLE IN OUT C1+ 1 10 IN MAX881R C1- 2 9 N.C. ON MAX881R SHDN NEGOUT 3 8 GND OFF C1+ POK 4 7 OUT CONTROLS POK GaAsFET PAs SHDN 5 6 FB DRAIN SWITCH C1- MAX NEGOUT FB GND N.C. = NOT INTERNALLY CONNECTED Maxim Integrated Products 1 For pricing delivery, and ordering information please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLELow-Noise Bias Supply in MAX with Power-OK for GaAsFET PA ABSOLUTE MAXIMUM RATINGS IN to GND.................................................................-0.3V to +6V Operating Temperature Range ...........................-40C to +85C SHDN to GND...........................................................-0.3V to +6V Junction Temperature......................................................+150C POK to GND ...........................................................-0.3V to +12V Storage Temperature Range .............................-65C to +165C C1+ to GND.................................................-0.3V to (V + 0.3V) Lead Temperature (soldering, 10s) .................................+300C IN C1-, NEGOUT, OUT, FB to GND ....................-6V to (V + 0.3V) IN Continuous Power Dissipation (T = +70C) A 10-Pin MAX (derate 5.6mW/C above +70C) ...........444mW Note 1: The output may be shorted to NEGOUT or GND if the package power dissipation is not exceeded. Typical short-circuit current is 35mA. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (Circuit of Figure 3, V = +3.6V, FB = GND, R = , SHDN = IN, T = -40C to +85C, unless otherwise noted. Typical values are at IN L A T = +25C.) (Note 2) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage Range V 2.5 5.5 V IN Preset Output Voltage V V 2.7V, I = 0 to 4mA -2.1 -2.0 -1.9 V OUT IN OUT Adjustable Output Voltage V V 2.5V, I = 0 to 4mA -(V - 0.6) -0.5 V OUT IN OUT IN Range T = +25C -0.515 -0.5 -0.485 A V 2.5V, IN FB Voltage V T = 0C to +85C -0.525 -0.475 V FB A I = 0 to 4mA OUT T = -40C to +85C -0.535 -0.465 A FB Input Current V = -0.5V -10 -100 nA FB Supply Current (Note 3) I 500 950 A Q Shutdown Supply Current I SHDN = GND 0.05 1 A SHUT Output Load Regulation V 2.7V, I = 0 to 4mA 26 mV/mA IN OUT Output Ripple I = 4mA, circuit of Figure 3b 1 mVp-p OUT Oscillator Frequency f 80 100 120 kHz OSC % of FB = OUT 90 92.5 95 POK Threshold V OUT POK Output Level V 2.5V, sinking 1mA 100 mV IN V = 11V 1 A POK Off Leakage Current POK SHDN Input High Voltage V V = 5.5V 2.2 V IH IN SHDN Input Low Voltage V V = 2.5V 0.35 V IL IN I Connected to IN or GND 1 A SHDN Input Current SHDN SHDN Input Capacitance C 10 pF IN V = 3V, R = 500 , V = 0 to V , IN L SHDN IN Startup Time t 1 ms START POK goes low Note 2: Specifications to -40C are guaranteed by design, not production tested. Note 3: MAX881R may draw high supply current during startup, up to the minimum operating supply voltage. To guarantee proper startup, the input supply must be capable of delivering 90mA more than the maximum load current. 2 MAX881R