19-0238; Rev 2; 4/96 NUAL KIT MA ATION U EET L H A S V A E T WS DA FOLLO Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaAsFET Bias ____________________________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: 1µA Max Over Temperature (MAX850/MAX852/MAX853) ♦ Low Cost, 8-Pin SO Package ______________Ordering Information ________________________Applications Cellular Phones Negative Regulated Power Supplies Personal Communicators, PDAs Wireless Data Loggers Continuously Adjustable GaAsFET Bias LCD-Bias Contrast Control __________Typical Operating Circuit PART MAX850C/D TEMP. RANGE 0°C to +70°C PIN-PACKAGE Dice* MAX850ISA MAX850ESA MAX851C/D MAX851ISA MAX851ESA MAX852C/D -25°C to +85°C -40°C to +850°C 0°C to +70°C -25°C to +85°C -40°C to +85°C 0°C to +70°C 8 SO 8 SO Dice* 8 SO 8 SO Dice* MAX852ISA -25°C to +85°C MAX852ESA -40°C to +85°C MAX853C/D 0°C to +70°C MAX853ISA -25°C to +85°C MAX853ESA -40°C to +85°C * Dice are specified at TA = +25°C only. 8 SO 8 SO Dice* 8 SO 8 SO ise* VIN = 4.5V to 10.0V (4 CELLS) C3 __________________Pin Configuration IN C1+ C1 C1- MAX850 MAX851 MAX852 VOUT = -4.1V (VGG of GaAsFET) TOP VIEW OUT C4 NEGOUT C2 C1+ 1 C1- 2 NEGOUT 3 SHDN* SHDN OSC FB GND SHDN* 4 (MAX850/853) MAX850 MAX851 MAX852 MAX853 8 IN 7 GND 6 OUT 5 FB** (MAX850–852) SO * MAX850: SHDN MAX851: SHDN MAX852: OSC * SHDN (MAX851) OSC (MAX852) ** CONT (MAX853) ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX850–MAX853 _______________General Description The MAX850–MAX853 low-noise, inverting, chargepump 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 current is 5mA. An internal 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 1µA max over temperature (5µA max for MAX851). MAX850–MAX853 Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaAsFET Bias ABSOLUTE MAXIMUM RATINGS Supply Voltage, VIN to GND ..................................-0.3V to 10.5V VNEGOUT to GND ...................................................-10.5V to 0.3V VIN to VNEGOUT .........................................................-0.3V to 21V VOUT to GND (Note 1) ........................................VNEGOUT to 0.3V SHDN or OSC (pin 4) Voltage to GND.........-0.3V to (VIN + 0.3V) Continuous Power Dissipation (TA = +70°C) SO (derate 5.88mW/°C above +70°C) ........................471mW Operating Temperature Ranges MAX85_ISA ......................................................-25°C to +85°C MAX85_ESA.....................................................-40°C to +85°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C 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 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 (+5V ≤ VIN ≤ +10V, GND = 0V, VOUT = -4.1V, RL = ∞, 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 Supply Voltage Range (Note 2) VIN Output Voltage VOUT CONDITIONS MIN MAX850–MAX852, VFB = 0V, RL = ∞ or 820Ω, Figure 2a -4.3 MAX853, VCTRL = 4.1V, RL = ∞ or 820Ω, Figure 2c -4.2 Supply Current UNITS 10 V -4.1 -3.9 -4.0 -0.5 to -(VIN - 1) VFBset MAX850–MAX852, no load, Figure 2b -1.32 IQ MAX850/MAX853, VIN = 10V, SHDN = 0V Shutdown Supply Current MAX V Output Voltage Range Set Voltage TYP 5 ISHUT MAX851, SHDN = 2V V -1.28 -1.24 V 2.0 3.0 mA 0.002 1 2 5 MAX852, OSC low MAX850–MAX852, VFB = 0V, RL = ∞ or 820Ω, Figure 2a 4 8 MAX853, VCTRL = 4.1V, RL = ∞ or 820Ω, Figure 2c 3 8 MAX850–MAX852 2 MAX853 1 VOUT Load Regulation mV/mA VOUT Ripple Oscillator Frequency (Note 3) µA 1 fOSC 100 mVp-p MAX850/MAX851/MAX853, TA = +25°C 80 Input High Voltage VIH Pin 4 2.0 120 kHz Input Low Voltage VIL Pin 4 0.5 V Input Current IIN Pin 4 ±1 µA Input Capacitance CIN Pin 4 V 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 250kHz square wave of 40% to 60% duty cycle. For best performance, use an 80kHz to 120kHz square wave with 50% duty cycle. 2 _____________________________________________________________________________________ Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaAsFET Bias OUTPUT VOLTAGE vs. INPUT VOLTAGE OVER TEMPERATURE -4.14 -4.13 -4.12 -4.11 TA = +25°C -4.10 TA = -40°C -4.09 TA = +85°C -4.08 -4.11 -4.07 -4.10 -4.06 60 MAX850-TOC3 MAX850-TOC2 IOUT = 2.5mA -4.12 OUTPUT VOLTAGE (V) -4.15 OUTPUT VOLTAGE (V) -4.13 MAX850-TOC1 -4.16 MAXIMUM OUTPUT CURRENT vs. INPUT VOLTAGE MAXIMUM OUTPUT CURRENT (mA) OUTPUT VOLTAGE vs. OUTPUT CURRENT 50 40 30 20 10 4.0 6.0 8.0 7.0 8.0 9.0 10.0 5.0 7.0 8.0 9.0 INPUT VOLTAGE (V) NO-LOAD SUPPLY CURRENT vs. INPUT VOLTAGE SUPPLY CURRENT vs. TEMPERATURE START-UP TIME vs. INPUT VOLTAGE 1.60 1.40 1.20 1.00 VIN = 10.0V 1.60 2.3 2.2 2.1 2.0 1.9 1.8 1.40 1.20 1.00 0.80 0.60 1.7 0.40 0.60 1.6 0.20 7.0 8.0 9.0 -40 10.0 IOUT = 5mA 1.80 0.80 -20 0 20 40 60 80 100 TEMPERATURE (°C) INPUT VOLTAGE (V) 5.0 6.0 7.0 8.0 9.0 10.0 INPUT VOLTAGE (V) VIN = 5.0V 70 MAX850-TOC7 EFFICIENCY vs. LOAD CURRENT 80 EFFICIENCY (%) 6.0 10.0 2.00 START-UP TIME (ms) MAX850-TOC4 2.5 2.4 SUPPLY CURRENT (mA) 1.80 5.0 6.0 INPUT VOLTAGE (V) 2.00 NO-LOAD SUPPLY CURRENT (mA) 6.0 5.0 10.0 OUTPUT CURRENT (mA) MAX850-TOC6 2.0 MAX850-TOC5 0 VIN = 6.0V 60 50 40 VIN = 10.0V 30 20 10 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 LOAD CURRENT (mA) _______________________________________________________________________________________ 3 MAX850–MAX853 __________________________________________Typical Operating Characteristics (Circuit of Figure 2a, VIN = 6V, TA = +25°C, unless otherwise noted.) _____________________________Typical Operating Characteristics (continued) (Circuit of Figure 2a, VIN = 6V, TA = +25°C, unless otherwise noted.) MAX850–MAX852 OUTPUT NOISE AND RIPPLE MAX853 OUTPUT NOISE AND RIPPLE VOUT 500µV/div VOUT 500µV/div 10µs/div VIN = 6.0V, VOUT = -4.1V, IOUT = 5mA, AC COUPLED 10µs/div VIN = 6.0V, VOUT = -4.1V, IOUT = 5mA, AC COUPLED MAX853 NOISE SPECTRUM MAX850–MAX852 NOISE SPECTRUM 70 70 60 60 50 50 40 40 NOISE (dBµV) NOISE (dBµV) MAX850–MAX853 Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaAsFET Bias 30 20 10 30 20 10 0 0 -10 -10 -20 -20 -30 0.1 1.0 10 100 1000 -30 0.1 1.0 10 100 FREQUENCY (kHz) FREQUENCY (kHz) NOTE: dBµV = 20 log VOUT 1µV 4 ______________________________________________________________________________________ 1000 Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaAsFET Bias MAX850/MAX851/MAX853 START-UP FROM SHUTDOWN MAX852 START-UP FROM SHUTDOWN VOUT 2V/div VOUT 2V/div VOSC 5V/div VSHDN 5V/div 200µs/div CIRCUIT OF FIGURE 2a, VIN = 6.0V, VOUT = -4.1V, IOUT = 5mA SHUTDOWN OCCURS WHEN 100kHz EXTERNAL CLOCK IS GATED OFF 200µs/div CIRCUIT OF FIGURE 2a, VIN = 6.0V, VOUT = -4.1V, IOUT = 5mA LINE-TRANSIENT RESPONSE LOAD-TRANSIENT RESPONSE 0.01mA IOUT VOUT 20mV/div 5mA VOUT 50mV/div 6.0V V IN 5.5V 2ms/div VOUT = -4.08V, IOUT = 5mA, AC COUPLED 1ms/div VOUT = -4.0V, AC COUPLED _______________________________________________________________________________________ 5 MAX850–MAX853 _____________________________Typical Operating Characteristics (continued) (Circuit of Figure 2a, VIN = 6V, TA = +25°C, unless otherwise noted.) MAX850–MAX853 Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaAsFET Bias ______________________________________________________________Pin Description PIN NAME FUNCTION MAX850 MAX851 MAX852 MAX853 1 1 1 1 C1+ Positive terminal for C1 2 2 2 2 C1- Negative terminal for C1 3 3 3 3 NEGOUT 4 – – 4 SHDN Active-low TTL logic level Shutdown Input – 4 – – SHDN Active-high TTL logic level Shutdown Input – – 4 – OSC 5 5 5 – FB – – – 5 CONT 6 6 6 6 OUT Output Voltage 7 7 7 7 GND Ground 8 8 8 8 IN Negative Output Voltage (unregulated), VNEGOUT = VIN + 0.2V External Clock Input Dual-Mode Feedback Input. When FB is grounded, the output is preset to -4.1V. To select other output voltages, connect FB to an external resistor divider. See Figure 2b. Control Voltage Input. To set VOUT, connect a resistor divider between OUT and a positive control voltage between 0V and 10V. See Figure 2c. Positive Power-Supply Input (4.5V to 10V) _______________Detailed Description The MAX850–MAX853 are low-noise, inverting, regulated 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- C1+ C1- ear regulator, and appears at OUT (Figure 1). The minimum (most negative) output voltage (VOUT) 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–MAX852. In addition, the excellent AC rejection of the linear regulator attenuates noise on the incoming supply. Up to 5mA is available at OUT. IN CHARGE PUMP C1+ MAX850 MAX851 MAX852 NEGOUT N C1- MAX853 OUT NEGOUT SHDN (MAX850) SHDN (MAX851) OSC (MAX852) IN CHARGE PUMP OUT N FB CONNECT TO GND TO SET VOUT = -4.1V SHDN -1.28V REF CONT CONTROL VOLTAGE GND Figure 1a. MAX850–MAX852 Block Diagram 6 GND Figure 1b. MAX853 Block Diagram ______________________________________________________________________________________ Low-Noise, Regulated, Negative Charge-Pump Power Supplies for GaAsFET Bias VIN Setting 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 alternate output voltage, connect FB to the midpoint of a resistor voltage divider from OUT to GND (Figure 2b). VIN must be 1.0V above the absolute value of VOUT to allow proper regulation. The output voltage is calculated from the formula below. Choose R2 to be between 100kΩ to 400kΩ. R2 VOUT = -1.28 1 + R1 ( ) MAX850–MAX853 __________Applications Information C1 1µF VOUT = -0.5V to -9V @ 5mA C1- C2 1µF C3 1µF IN C1+ MAX853 OUT NEGOUT C4 10µF R2 100k SHDN CONT R1 100k GND VCTRL (0V TO 10V) VIN Figure 2c. MAX853 Standard Application Circuit C3 1µF IN C1 1µF C1+ C1- C2 1µF MAX850 MAX851 MAX852 OUT R2 VOUT = - VCTRL R1 C4 10µF NEGOUT SHDN* SHDN OSC For the MAX853, set the output voltage, VOUT, by connecting a resistor voltage divider between OUT and a positive control voltage, VCTRL (Figure 2c.) VOUT = -4.1V (VGG of GaAsFET) FB GND *MAX850: SHDN MAX851: SHDN MAX852: OSC Figure 2a. MAX850/MAX851/MAX852 Standard Application Circuit VIN C3 1µF IN C1 1µF C1+ C1- C2 1µF MAX850 MAX851 MAX852 OUT VOUT = (-1.28V) 1+ R2 R1 ( C4 10µF NEGOUT R2 100k SHDN* SHDN OSC FB GND Shutdown The MAX850–MAX853 feature a shutdown mode that reduces the supply current to 1µA max over temperature (5µA 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. R1 100k ) Capacitors Use capacitors with low effective series resistance (ESR) to maintain a low dropout voltage (VIN - |VOUT|). The overall dropout voltage is a function of the charge pump’s output resistance and the voltage drop across the linear regulator (N-channel pass transistor). At the 100kHz switching frequency, the charge-pump output resistance is a function of C1 and C2’s ESR. Therefore, minimizing the ESR of the charge-pump capacitors minimizes the dropout voltage. 1µF, 0.8Ω ESR capacitors are recommended for C1, C2, and C3. C4 should be 10µF, 0.2Ω 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 *MAX850: SHDN MAX851: SHDN MAX852: OSC Figure 2b. MAX850/MAX851/MAX852 Adjustable Configuration Use the MAX852 to minimize system interference caused by conflicting clock frequencies. An external oscillator can set the charge-pump frequency and reduce clock frequency _______________________________________________________________________________________ 7 MAX850–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 frequency is 250kHz, and the minimum frequency is 50kHz. ___________________Chip Topography IN C1+ Layout and Grounding Good layout is important, primarily for good noise performance. 1) Mount all components as close together as possible. 2) Keep traces short to minimize parasitic inductance and capacitance. This includes connections to FB. C1- GND 0.127" (3.226mm) NEGOUT 3) Use a ground plane. Noise and Ripple Measurement Accurately measuring the output noise and ripple is a challenge. Brief differences in ground potential between the MAX850–MAX853 circuit and the oscilloscope (which result from the charge pump’s switching action) cause ground currents in the probe’s wires, inducing sharp voltage spikes. For best results, measure directly across the output capacitor (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 ripple measurement. OUT FB (MAX850–852) CONT (MAX853) SHDN (MAX850/853) SHDN (MAX851) OSC (MAX852) 0.085" (2.159mm) TRANSISTOR COUNT: 164 SUBSTRATE CONNECTED TO IN ________________________________________________________Package Information DIM E A A1 B C D E e H h L α H INCHES MAX MIN 0.069 0.053 0.010 0.004 0.019 0.014 0.010 0.007 0.197 0.189 0.157 0.150 0.050 BSC 0.244 0.228 0.020 0.010 0.050 0.016 8˚ 0˚ MILLIMETERS MIN MAX 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 4.80 5.00 3.80 4.00 1.27 BSC 5.80 6.20 0.25 0.50 0.40 1.27 0˚ 8˚ 21-325A h x 45˚ D α A 0.127mm 0.004in. e A1 C L 8-PIN PLASTIC SMALL-OUTLINE PACKAGE B 8 ______________________________________________________________________________________