19-0238: Rev 2: 4/96 MAXKILM Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaAsFET Bias General Description The MAX850MAX853 low-noise, inverting, charge- pump power supplies are ideal for biasing GaAsFETs in cellular telephone transmitter amplifiers. The MAX850-MAX852 offer both preset (-4.1V) and adjustable (-0.5V to -9.0V) output voltages. The MAX853 uses an external positive control voltage to set the negative output voltage. Input voltage range for all four devices is 4.5V to 10V. Output currentis 5mA. An intemal linear regulator reduces the output voltage ripple to 2mVp-p. With a well-filtered control voltage (VCTRL), the MAX853 achieves typical output ripple of less than 1mVp-p. Supply current is 3mA max, and shutdown current is less than 1A max over temperature (BLA max for MAX851). Features Fixed -4.1V or Adjustable -0.5V to -9V Output at 5mA 4.5V to 10V Input Voltage Range # 2mVp-p Output Voltage Ripple (MAX850-MAX852) 1mVp-p Output Voltage Ripple (MAX853) 100kHz Charge-Pump Switching Frequency (MAX850/MAX851/MAX853) External Synchronizing Clock Input (MAX852) Logic-Level Shutdown Mode: 1A Max Over Temperature (MAX850/MAX852/MAX853) + Low Cost, &Pin SO Package Ordering Information PART TEMP. RANGE PIN-PACKAGE Applications MAX850C/D 0% to +70 Dice Cellular Ph MAX850ISA -25C to +85C 8 SO eumar mnones MAX850ESA 40C to +850C 850 Negative Regulated Power Supplies MAXB51C/D 0c tos70% Dice* Personal Communicators, PDAs MAX851ISA -25C to +85C 8so Wireless Data Loggers MAX851ESA -40C to +85C 8 S0 Continuously Adjustable GaAsFET Bias MAX852C/D O to +70C Dice* LCD-Bias Contrast Control MAX852ISA 25C to +85C 8 SO MAX852ESA -40%C to +85C 850 MAX853C/D 0 to+70 Dice* Typical O . Ci . MAX853ISA -25C to +85C 8 SO ypical Operating Circuit MAX853ESA -40C to +85C 8 SO * Dice are specilied at Ta = +25C only. Vin = 4.5 to 10.0 (4 CELLS) + TS Pin Configuration IN = Ct+ ~ +L | Axim Yout=-4.1 TOP VIEW a (Vag of GaASFET) Ld ct MAKE uy MAXESi ~.* MAXG52 cA : Co NT * cL Aaxnan El @ = c+ [2] mass = G] ao +L Mast = | Shon Neca [3] ayggo [a] our | SHDN rB SHON [a] MAX853 il FBY* Ost (MAX850/853) (MAX850-B52) GND so *MAX850, SHDN |__, MAXB51 SHDN * SHDN (MAXB51} ** CONT (MAXE53} MAXBE2 OSC. = CSC (MAXBE2} MAXI Maxim integrated Products 1 For free samples & the iatest literature: http:/;www.maxim-ic.com, or phone 1-800-998-8800 ESEXVNW-OSEXVWMAX850-MAX853 Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaASFET Bias ABSOLUTE MAXIMUM RATINGS Supply Voltage, Vin to GND .0.3 to 10.5V VNEGoUT to GND........... VIN to VNEGOUT ..-..-- Voutto GND (Note 1)........ o SHDN or OSC (pin 4) Voltage to GND.........-0.3V to (VIN + 0. yy Continuous Power Dissipation (Ta = +70 C) SO (derate 5.88mMW/C above +70) oo... ee 471mWw Operating Tem perature Ranges MAX85_ISA.. 25C to +85C MAX85_ESA.... 40 to 485C Storage Temperature Range ben 65C to +160C Lead Temperature (soldering, 10sec} .... +300 Note 1: The output may be shorted to NEGOUT or GND if the package power dissipation is not exceeded. Typical short-circuit current to GND is 50mA. Stresses Deyond those listed under Absolute Maximum Ratings" may cause permanent damage io the device. These are siress 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 ito absolute maximum rating conditions jor exiended periods may affect device reliability. ELECTRICAL CHARACTERISTICS G5V < Vins +10V, GND = OV, Vout = 4.1, AL = , Ta = TMIN to TMAX, Unless otherwise noted. A 100kHz, 50% duty cycle square wave between GND and Vin is applied to OSC on the MAX852.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX | UNITS Supply Voltage Range (Note 2) VIN 5 10 Vv MAX8504MAX852, Vpp = OV, RL = or 8200, Figure 2a 43 4 3.9 Output Voltage Vout Vv MAX853, VoTAL = 4.1, 42 4.0 RAL = or 8200, Figure 2c . Output Voltage Range -0.5 to -(Vin - 1) Vv Set Voltage VEFBset MAX850-MAX852, no load, Figure 2b -1.32 -1.28 -1.24 Vv Supply Current la 2.0 3.0 mA MAX850/MAX853, Vin = 10V, SHDN = OV 0.002 1 Shutdown Supply Current ISHUT MAX851, SHDN = 2V 2 5 pA MAX852, OSC low 1 MAX850-MAX852, Vp = OV, 4 8 RL = ~ or 8200, Figure 2a Vout Load Regulation m/mA MAX853, VoTAL = 4.1V, 3 8 RL = ~ or 8209, Figure 2c Riopl MAxX8504MAX852 2 y fouT Ripple mvp - PP MAX853 1 PP Oscillator Frequency (Note 3) fosc MAX850/MAX85 1/MAX853, Ta = +25C 80 100 120 kHz Input High Voltage VIH Pin 4. 2.0 Vv Input Low Voltage VIL Pin 4 0.5 Vv Input Current lin Pin 4 +1 HA Input Capacitance CIN Pin 4 10 pF Note 2: The supply voltage can drop to 4.5V, but the output may no longer sink 5mA at -4.1V. Note 3: The MAX852 will operate with a 50kHz to 250kKHz square wave of 40% to 60% duty cycle. For best performance, use an 80kHz to 120kHz square wave with 50% duty cycle. MAAXIAALow-Noise, Regulated, Negative Charge-Pump Power Supplies for GaAsFET Bias (Circuit of Figure 2a, VIN = 6V, Ta = +25C, unless otherwise noted.) OUTPUT VOLTAGE vs, OUTPUT CURRENT # & + > on oa OUTPUT VOLTAGE () a a t so Att 4410 a 20 40 60 80 OUTPUT CURRENT (mA) NO-LOAD SUPPLY CURRENT vs, INPUT VOLTAGE NO-LCAD SUPPLY CURRENT (mA) se = @ es S$ 8 6 8 8 8 a oo o a @ o 50 60 70 ao INPUT VOLTAGE (} MAAXLIA 90 100 1M aNa50-TOCA 100 OUTPUT VOLTAGE [) SUPPLY CURRENT (mA} EFFICIENCY (%} 25 24 23 22 214 20 1g 18 80 40 60 50 40 30 20 OUTPUT VOLTAGE vs. INPUT VOLTAGE CVER TEM PERATURE lout = 2 SrA Manas0-T0G2 Ta = 425C Ta=-40C Ta = +85C 50 60 70 80 90 100 INPUT VOLTAGE () SUPPLY CURRENT vs, TEMPERATURE Vin= 10 0V 40-2000 0 20 4006600 BO 100 TEMPERATURE (C) EFFICIENCY vs. LOAD CURRENT Vin= 5 OV MAMS0-T0C? Viy= 6 OV Vin = 10 OV 10 15 20 25 30 35 40 45 50 LOAD CURRENT {ma} MAXIMUM OUTPUT CURRENT (mAj 200 180 160 hRoo- oe o START-UP TIME (ms) o- eo = 6 o a a 040 020 50 50 MAXIMUM OUTPUT CURRENT vs, INPUT VOLTAGE 60 60 70 80 INPUT GLTAGE (} START-UP TIME vs. INPUT VOLTAGE 90 Typical Operating Characteristics 100 lout = SimA 70 ao INPUT OLTAGE (} 90 100 ESEXVN-OSEXVWMAX850-MAX853 Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaASFET Bias NOISE (Bu) MAX850-M AX852 OUTPUT NOISE AND RIPPLE Vout SOOUW/dIy 10pis/div Vin= 6 OV, Vout =-4 14, Icut=5mA, AC COUPLED MAX850-M AX852 NOISE SPECTRUM of 10 10 400 4000 FREQUENCY (KHz) NOISE (dByaV) Typical Operating Characteristics (continued) (Circuit of Figure 2a, VIN = 6V, Ta = +25C, unless otherwise noted.) MAX853 OUTPUT NOISE AND RIPPLE 10usidiv Vin =6 OV, Vogt = -4 1, [our =5mA, AC COUPLED MAX853 NOISE SPECTRUM a Pa NR NOTE: dBuV = 20 log SMAAKLow-Noise, Regulated, Negative Charge-Pump Power Supplies for GaASFET Bias MAX850/M AX851/MAX853 START-UP FROM SHUTDOWN 200usidiv CIRCUIT OF AGURE2Za, Vin =6 OV, Vou =-4 1, lour=5mnA LINE- TRANSIENT RESPONSE 2mefdiv Vout =-4 08, louT=5rn, AC COUPLED SAAXIAA Typical Operating Characteristics (continued) (Circuit of Figure 2a, VIN = 6V, Ta = +25C, unless otherwise noted.) MAX852 START-UP FROM SHUTDOWN Vout id Ves Svidiv 200usidiv CIRCUIT OF AGURE 2a, Vin =6 OV, VouT=-4 1M, lour=5inA SHUTDOWN CCCURS WHEN 100kHz EXTERNAL CLOCK IS GATED OFF LOAD- TRANSIENT RESPONSE a O1mA louT 5mA Vout Som civ Vour=-4 OV, AC. COUPLED 5 ESEXVN-OSEXVWMAX850-MAX853 Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaASFET Bias Pin Description PIN MAX850 | MAX851 | MAX852 | MAX853 NAME FUNCTION 1 1 1 Ci+ Positive terminal tor C1 2 2 2 C1- Negative terminal for C1 3 3 3 NEGOUT | Negative Gutput Voltage (unregulated), VwEGouT = Vin + 0.2 4 - 4 SHDN | Active-low TTL logic level Shutdown Input - - - SHDN Active-high TTL logic level Shutdown Input - 4 - osc External Clock Input Dual-Mode Feedback Input. When FB is grounded, the output is preset to 5 5 - Fe -4.1V. To select other output voltages, connect FB to an external resistor divider. See Figure 2b. _ _ 5 CONT Control Voltage Input, To set VOUT, connect a resistor divider between GUT and a positive control voltage between OV and 10V. See Figure 2c. 6 6 6 OUT Qutput Voltage 7 7 7 GND Ground 8 8 8 IN Positive Power-Supply Input (4.5V to 10) Detailed Description The MAX850-MAX853 are low-ncise, inverting, regulat- ed charge-pump power supplies designed for biasing GaAsFET devices, such as power-amplifier modules in cellular handsets. The applied input voltage (VIN) is first inverted to a negative voltage at NEGOUT by a capacitive charge pump. This voltage is then regulated by an internal lin- ear regulator, and appears at OUT (Figure 1). The mini- mum (most negative) output voltage (VouUT) achievable is the inverted positive voltage, plus the 1.0V required by the post-regulator. The ripple noise induced by the charge-pump inverter is reduced by the linear regulator to 2mVp-p at VouT for the MAX850-VMAX852. In addi- tion, the excellent AC rejection of the linear regulator attenuates noise on the incoming supply. Up to 5mA is available at OUT. Git EF lt "Tot Tc NEGCUT QUT a a mc + SHDN (MAX850) B SHON (MAX851) OBC (MAXBED| CONNECT TO GND TO SET Vour=-41 GND Ct mcs hae + Tice maxim Tt a MANXB53 - NEGQUT N UT ~L Le E TE SHDN A CONT CONTROL VOLTAGE Figure ta. MAX850-MAX852 Block Diagram Figure 1b, MAX853 Block Diagram SMAAKLow-Noise, Regulated, Negative Charge-Pump Power Supplies for GaAsFET Bias Applications Information Seiting the Output Voltage For the MAX850-MAX852, select either a fixed or an adjustable output voltage. Connect FB directly to GND to select the fixed -4.1V output (Figure 2a). To select an alter- nate cutput voltage, connect FB to the midpoint of a resis- tor voltage divider from OUT to GND (Figure 2b). Vn must be 1.0V above the absolute value of VouT to allow proper regulation. The output voltage is calculated from the formu- la below. Choose R2 to be between 100k to 400kQ. R2 VouT = (-1.28) (1. Vin | + ca IN lL tpF ct Cit WAAXLAA Vout=-4.1 1 a MANaSO (Vgq of GaAsFET) Cl Axes OUT m MAX852 uF ce [| UT TF wa ~ = SHON ] SHDN B osc GND *MAX850 SHDN MAXe51 SHDN L_,_ MAXe52 OSC a5 Figure 2a. MAX850/MAX85 T/MAX852 Standard Application Circuit Vin ? + c3 IN iF Ci+ c+ | AALADCLAA tur Vour = (-1.28) (+) MAX850 Ri Cl MAxgst OUT MAXAS2 a ce [| Nau Wee = SHDN* ] son OSC GND *MAXes0. SHON MAX851 SHDN MAXes2 OSC. = Figure 2b. MAX850/MAX851/MAX852 Adjustable Configuration SAAXIAA Vin ? + G3 che IN <tnF MAXLA THF TI Cl. MANB53 = OUT ce LE NEGOUT Vout = -0.5 to-SV @ 5mA SHON CONT He Vere (OVO 10) Figure 2c. MAX853 Slandard Application Circuit For the MAX853, set the output voltage, VOUT, by con- necting a resistor voltage divider between OUT and a positive control voltage, VCTRL (Figure 2c.) R2 Vout = - Votre (= Shutdown The MAX850-MAX853 feature a shutdown mode that reduces the supply current to 1WA max over temperature (5uA max for the MAX851). The MAX850 and MAX853 have an active-low TTL logic level SHDN input, whereas the MAX851 has an active-high SHDN input. To shut down the MAX852, set the OCSC input to a logic-low level. The device is powered up by the resumption of the clock signal. Capacitors Use capacitors with low effective series resistance (ESR) to maintain a low dropout voltage (VIN - [YouT|). The overall dropout voltage is a function of the charge pumps output resistance and the voltage drop across the linear regulator (N-channel pass transistor). At the 100kHz switching fre- quency, the charge-pump output resistance is a function of C1 and Cs ESR. Therefore, minimizing the ESR of the charge-pump capacitors minimizes the dropout voliage. IHF, 0.80 ESR capacitors are recommended for C1, C2, and C3. C4 should be 10UF, 0.20 ESR. All capacitors should be either surface-mount chip tantalum or chip ceramic types. External capacitor values may be adjusted to optimize size and cost. Switching-Frequency Control! Use the MAX852 to minimize system interference caused by conflicting clock frequencies. An extemal oscillator can set the charge-pump frequency and reduce clock frequency 7 ESEXVN-OSEXVWMAX850-MAX853 Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaASFET Bias sensitivity and interference. The clock must be a square wave between 40% and 60% duty cycle. The maximum clock fre- quency is 250kHz, and the minimum frequency is 50kHz. Layout and Grounding Good layout is important, primarily for good neise perfor- mance. 1) Mount all components as close together as possible. 2) Keep traces short to minimize parasitic inductance and capacitance. This includes connections to FB. 3) Use aground plane. Noise and Ripple Measurement Accurately measuring the output noise and tipple is a chal- lenge. Brief differences in ground potential between the MAX850-VMAX853 circuit and the oscilloscope (which result from the charge pumps switching action) cause ground currents in the probe's wires, inducing sharp voltage spikes. For best results, measure directly across the output capaci- tor (C4). Do not use the ground lead of the oscilloscope probe; instead, remove the probe's tip cover and touch the ground ring on the probe directly to C4's ground terminal. You can also use a Tektronix chassis mount test jack (part no. 131-0258) to connect your scope probe directly. This direct connection gives the most accurate noise and rip- ple measurement. Chip Topography GND 0.127" {3.226mm) FB (MAK850-852} CONT (MAXa5 3) SHDN (MAX850/853) SHDN (MAX851} osc (MAKE52) 0.085" (2.159mm) TRANSISTOR COUNT: 164 SUBSTRATE CONNECTED TO IN Package Information Wont 4 Al Nt ocain =, [otzemm c DIM INCHES MILLIMETERS MIN MAX MIN MAX A_| 0.053 | 0.069 1.35 1.75 A1_| 0.004 | 0.010 0.10 0.25 B | 0.014 | 0.019 0.35 0.49 Cc | 0.007 | 0.010 0.19 0.25 D_ | 0.189 | 0.197 4.80 5.00 E | 0.150 | 0.157 3.80 4.00 e 0.050 BSC 1.27 BSC H | 0.228 | 0.244 5.80 6.20 A 0.010 | 0.020 0.25 0.50 L_| 0.016 | 0.050 0.40 1.27 aw O 8 O e 2BA-325A I-11 8-PIN PLASTIC 4 SMALL-OUTLINE PACKAGE SMAAK