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19-1174; Rev 0; 12/96
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies
_______________General Description
The MAX768 low-noise, dual-output, regulated charge pump provides a negative output for biasing GaAsFET power amplifiers, and a positive output for powering voltage-controlled oscillators (VCOs) in wireless handsets. The outputs can also be used to power LCDs. Output ripple is less than 2mVp-p. The MAX768 is intended for use in low-voltage systems where a simple charge-pump inverter is inadequate, or where the VCO needs more range to improve its signal-to-noise ratio. The input range is 2.5V to 5.5V, enabling direct power from 1Li+ and 3-cell NiMH/NiCd batteries. The MAX768 includes a voltage-doubler charge pump, followed by an inverting charge pump. This combination produces unregulated outputs that are 2x the input. Two internal low-dropout linear regulators provide the low-noise, regulated positive and negative outputs. Output current is guaranteed to be at least 5mA per output. The linear regulators use CMOS devices, so the quiescent current remains independent of output loading (even in dropout), and the dropout voltage approaches zero with no load current. The MAX768 has two preset switching frequencies (25kHz or 100kHz), or can be synchronized by an external clock from 20kHz to 240kHz. This flexibility permits users to optimize their designs based on noise, capacitor size, and quiescent-supply-current criteria. The device features Dual ModeTM operation: the output voltage is preset to +5V and -5V, or can be adjusted by adding external resistor dividers. Other features include independent shutdowns and a logic output that signals when the negative voltage has risen to within 10% of its regulation setpoint (to protect the power amplifier GaAsFET). The MAX768 is available in a space-saving, 16-pin QSOP, which is the same size as a standard 8-pin SO.
____________________________Features
o Dual Positive/Negative Regulated Outputs: 5VOUT from 3VIN o Output-Ready Indicator to Protect GaAsFET PAs o 2.5V to 5.5V Input Voltage Range o Low-Noise Output Ripple: < 2mVp-p o Synchronizable Switching Frequency o Uses Only Small, Low-Cost Capacitors o 0.1A Independent Shutdown Controls o Adjustable Output Voltages o Small 16-Pin QSOP Package
MAX768
______________Ordering Information
PART MAX768C/D MAX768EEE TEMP. RANGE 0C to +70C -40C to +85C PIN-PACKAGE Dice* 16 QSOP
*Dice are specified at TA = +25C, DC parameters only.
Pin Configuration appears at end of data sheet. Dual Mode is a trademark of Maxim Integrated Products.
__________Typical Operating Circuit
VIN (3.0V TO 5.5V)
C7 IN POUT V+ C3 C5 POSITIVE OUTPUT +5V
SYNC PSHDN NSHDN C1+ C1 C1C2+ C2 C2-
________________________Applications
GaAsFET Power Amp Bias Voltage-Controlled Oscillator (VCO) Supply Tuner Diode Power Supply Positive and Negative LCD Supply Cellular Phone PCS and Cordless Phone Wireless Handsets Wireless Handheld Computers Wireless PCMCIA Cards Modems
MAX768
VNOUT RDY SETN GND SETP
C4 C6 NEGATIVE OUTPUT -5V OUTPUTREADY SIGNAL
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies MAX768
ABSOLUTE MAXIMUM RATINGS
VIN, C1-, SYNC, PSHDN, NSHDN to GND...............-0.3V to +6V V+, C1+, C2+, RDY to GND...................................-0.3V to +12V SETP to GND .......................................................... -0.3V to +3V SETN to GND............................................................-3V to +0.3V V-, C2- to GND ...................................................... -12V to +0.3V OUTP, OUTN Short Circuited to GND .......................Continuous NOUT to V- ........................................................... -0.3V to +12V POUT to V+ ........................................................... -12V to +0.3V Continuous Power Dissipation (TA = +70C) QSOP (derate 8.70mW/C above +70C) ......................696mW Operating Temperature Range MAX768EEE.......................................................-40C to +85C Maximum Junction Temperature .....................................+150C Storage Temperature Range .............................-65C to +165C Lead Temperature (soldering, 10sec) .............................+300C
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
(VIN = +3V, SYNC = IN, SETN = SETP = GND, NSHDN = PSHDN = IN, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C. See Figure 2.) (Note 1) PARAMETER Input Voltage Range Minimum Input Start-Up Voltage Positive Output Voltage Negative Output Voltage Positive Output Voltage Adjustable Range Negative Output Voltage Adjustable Range Maximum POUT, NOUT Output Currents No-Load Supply Current at 100kHz (both regulators active) No-Load Supply Current at 100kHz (negative regulator off) No-Load Supply Current at 25kHz (both regulators active) Dropout Voltage (2 x VIN - |VOUT|) Line Regulation Load Regulation Output Voltage Noise Shutdown/SYNC Logic-Low Input Threshold Shutdown/SYNC Logic-High Input Threshold SHUTDOWN SHDN Input Bias Current Shutdown Supply Current VSHDN = 3V NSHDN = PSHDN = SYNC = GND 0.1 0.1 2 10 A A 2.0 ILOAD = 0 0mA < ILOAD < 5mA, VIN = 3.0V to 5.5V 0mA < ILOAD < 5mA, VIN = 3.0V to 5.5V (Note 2) (Note 3) VIN = 3V, VPOUT 4.81V, VNOUT -4.82V VIN = 3.0V VIN = 5.5V NSHDN = GND VSYNC = GND 2 x VIN - | VOUT | VIN = 3V to 5.5V IPOUT = 0mA to 5mA, INOUT = 0mA to -5mA CPOUT = CNOUT = 10F, 10kHz < f < 1MHz POUT NOUT IPOUT = INOUT = 0.1mA IPOUT = INOUT = 5mA -0.12 4.81 -5.10 1.25 -11 5 0.8 1.5 0.3 0.45 20 420 0.0 0.06 1.2 1.7 0.4 900 0.12 0.12 0.80 1.4 CONDITIONS MIN 3.0 2.5 5.00 -5.00 5.14 -4.82 11 -1.25 TYP MAX 5.5 UNITS V V V V V V mA mA mA mA mV %/V %/mA mVp-p V V
2
_______________________________________________________________________________________
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +3V, SYNC = IN, SETN = SETP = GND, NSHDN = PSHDN = IN, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C. See Figure 2.) (Note 1) PARAMETER SYNC SYNC Frequency Range (external) SYNC Duty Cycle (external) Oscillator Frequency (internal) SYNC Input Leakage Current SET INPUT Positive Set-Reference Voltage Negative Set-Reference Voltage IPOUT = 0.1mA INOUT = 0.1mA VSETP = VSETN = 1.3V Percent of VNOUT, INOUT = 5mA ISINK = 2mA VRDY = 10V 0.01 10 85 TA = +25C TA = -40C to + 85C TA = +25C TA = -40C to + 85C 1.217 1.215 -1.270 -1.275 1.25 1.25 -1.25 -1.25 0.01 94 1.283 1.285 -1.230 -1.225 0.1 98 0.25 2 V V A % V A mA SYNC = GND (divide by 4) VSYNC = 3V 20 40 21.5 85 25 100 0.1 240 60 28.5 115 2 kHz % kHz A CONDITIONS MIN TYP MAX UNITS
MAX768
RDY OUTPUT
SETP, SETN Input Leakage Current RDY Output Threshold Output Low Voltage Output Off Current Maximum Sink Current
Note 1: Parameters to -40C are guaranteed by design, not production tested. Note 2: Maximum output voltage range is from the positive reference voltage to 2 x VIN - dropout voltage. Note 3: Maximum output voltage range is from the negative reference voltage to -2 x VIN + dropout voltage.
__________________________________________Typical Operating Characteristics
(SYNC = IN, TA = +25C, unless otherwise noted.)
mVRMS OUTPUT VOLTAGE vs. OUTPUT CURRENT
MAX768-TOC01
POUT OUTPUT VOLTAGE vs. OUTPUT CURRENT
MAX768-TOC02
NOUT OUTPUT VOLTAGE vs. OUTPUT CURRENT
-4.3 OUTPUT VOLTAGE (V) -4.4 -4.5 IN = 3.0V -4.6 -4.7 -4.8 ONLY NOUT LOADED
MAX768-TOC03
0.30 IN = 3.0V OUTPUT VOLTAGE (mVRMS)
5.2 ONLY POUT LOADED 5.0 OUTPUT VOLTAGE (V) 4.8 IN = 3.0V 4.6 4.4 4.2 IN = 4.0V
-4.2
0.20
NOUT = -5V POUT = +5V
0.10
-4.9 -5.0 0 5 10 15 20 25 30 0 5 10 15 20
IN = 4.0V 25 30
0 0 5 10 15 20 25 OUTPUT CURRENT (mA)
4.0 OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
_______________________________________________________________________________________
3
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies MAX768
____________________________Typical Operating Characteristics (continued)
(SYNC = IN, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SYNC FREQUENCY
MAX768-TOC04
CHARGE-PUMP FREQUENCY vs. SUPPLY VOLTAGE
MAX768-TOC05
CHARGE-PUMP FREQUENCY vs. TEMPERATURE
VIN = 3.3V CHARGE-PUMP FREQUENCY (kHz) 100 80 60 40 SYNC = GND 20 0 SYNC = IN
MAX768-TOC06
4
115 SYNC = IN CHARGE-PUMP FREQUENCY (kHz) 100 85 70 55 40 SYNC = GND 25 10
120
SUPPLY CURRENT (mA)
3 VIN = 5.0V 2
1
VIN = 3.3V
0 0 40 80 120 160 200 240 280 320 SYNC FREQUENCY (kHz)
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
-55 -35 -15
5
25
45
65
85 105 125
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
SHDN SUPPLY CURRENT vs. TEMPERATURE
MAX768-TOC07
SHDN SUPPLY CURRENT vs. TEMPERATURE
MAX768-TOC08
SUPPLY CURRENT vs. SUPPLY VOLTAGE (NO LOAD)
1.6 SUPPLY CURRENT (mA) 1.4 1.2 1.0 0.8 f = 25kHz 0.6 0.4 0.2 f = 100kHz
MAX768-TOC09
20 18 SHDN SUPPLY CURRENT (A) 16 14 12 10 8 6 4 2 0 -40 -15 10 35 60 VIN = 3.3V VIN = 5.0V
0.40 0.35 SHDN SUPPLY CURRENT (A) 0.30 0.25 0.20 0.15 0.10 0.05 0 -0.05 VIN = 3.3V -40 -15 10 35 60 VIN = 4.0V VIN = 5.0V
1.8
0 85 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V)
85
TEMPERATURE (C)
TEMPERATURE (C)
EFFICIENCY vs. LOAD CURRENT (NOUT ONLY LOADED)
MAX768 TOC10
EFFICIENCY vs. OUTPUT CURRENT (POUT ONLY LOADED)
MAX768 TOC11
EFFICIENCY vs. OUTPUT CURRENT LOAD BETWEEN POUT AND NOUT
80 70 EFFICIENCY (%) 60 50 40 30 20 10 0 VIN = 4.0V
MAX768 TOC12
90 80 70 EFFICIENCY (%) 60 50 40 30 20 10 0 0.1 1 10 VIN = 4.0V VIN = 3.0V
90 80 70 EFFICIENCY (%) 60 50 40 30 20 10 0 VIN = 4.0V VIN = 3.0V
90 VIN = 3.0V
100
0.1
1
10
100
0.1
1
10
100
LOAD CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
4
_______________________________________________________________________________________
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies
_____________________________Typical Operating Characteristics (continued)
(SYNC = IN, TA = +25C, unless otherwise noted.)
POUT MAXIMUM OUTPUT CURRENT vs. SUPPLY VOLTAGE
MAX768-TOC13
MAX768
NOUT MAXIMUM OUTPUT CURRENT vs. SUPPLY VOLTAGE
80 70 60 50 40 30 20 10 0 ONLY NOUT LOADED
MAX768-TOC14
140 ONLY POUT LOADED MAXIMUM OUTPUT CURRENT (mA) 120 100 80 60 40 20 0 2.5 3.0 3.5 4.0 4.5
90 MAXIMUM OUTPUT CURRENT (mA)
5.0
2.5
3.0
3.5
4.0
4.5
5.0
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
TIME TO EXIT SHUTDOWN
MAX768-TOC15
+3V, PSHDN = NSHDN +5V, VPOUT
0V
-5V, VNOUT 0V, RDY 1ms/div
POUT OUTPUT NOISE AND RIPPLE
MAX768-TOC16
NOUT OUTPUT NOISE AND RIPPLE
MAX768-TOC17
VPOUT, 500V/div AC COUPLED
VNOUT, 500V/div AC COUPLED
500s/div POUT = +5V AT 5mA IN = 3.0V NOUT = -5V AT 5mA IN = 3.0V
500s/div
_______________________________________________________________________________________
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Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies MAX768
______________________________________________________________Pin Description
PIN 1 2 3 4 5 6 7 8 NAME C1GND C2VNOUT SETN NSHDN PSHDN FUNCTION Negative Terminal of the Doubler Charge-Pump Capacitor. See Table 2 for capacitor selection. Ground Negative Terminal of the Inverter Charge-Pump Capacitor Inverter Charge-Pump Output. See Table 2 for capacitor selection. Negative Regulator Output. See Table 2 for capacitor selection. Set Negative Output Voltage Input. Connect SETN to GND for factory-preset -5V. Connect a resistor divider between NOUT, SETN, and GND for custom output voltage setting. Negative-Supply Shutdown Input. Pull NSHDN low to turn off the inverting charge pump, the negative regulator, and the bias-ready indicator. If PSHDN is also low, the part completely shuts down. Positive-Supply Shutdown Input. Pull PSHDN low to turn off the positive regulator. If NSHDN is also low, the part completely shuts down. Clock Synchronizing Input. Connect an external 20kHz fCLK 240kHz to SYNC to synchronize the MAX768 to that frequency. Connect SYNC to GND to select the internal 25kHz clock, or to IN for the internal 100kHz clock. Output-Ready Indicator. This open-drain output pulls to GND when the negative output voltage (NOUT) is within 10% of the regulation voltage. Set Positive Output Voltage Input. Connect SETP to GND for factory-preset +5V output. Connect a resistor divider between POUT, SETP, and GND for custom output voltage setting. Positive Regulator Output. See Table 2 for capacitor selection. Doubler Charge-Pump Output. See Table 2 for capacitor selection. Positive Terminal of the Doubler Charge-Pump Capacitor. See Table 2 for capacitor selection. Supply (3V to 5.5V). Bypass IN with 4.7F to GND. Positive Terminal of the Inverter Charge-Pump Capacitor. See Table 2 for capacitor selection.
9
SYNC
10 11 12 13 14 15 16
RDY SETP POUT V+ C1+ IN C2+
6
_______________________________________________________________________________________
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies MAX768
IN V+ P POUT
C1+ VOLTAGE DOUBLER C1PSHDN SYNC NSHDN C2+ VOLTAGE INVERTER C2VSHDN +1.25V REF -1.25V
MAX768
SETP CONNECT TO GND TO SET VPOUT = +5V GND
N RDY
SETN CONNECT TO GND TO SET VNOUT = -5V N NOUT
Figure 1. Functional Diagram
_______________Detailed Description
The MAX768 requires only seven external capacitors to implement a regulated voltage doubler/inverter. These can be ceramic or polarized electrolytic capacitors ranging from 2.2F to 47F. Figure 1 is a functional diagram of the MAX768. The applied input voltage (VIN) is first doubled to a value of 2VIN by a capacitor charge pump and then stored in the V+ reservoir capacitor. Next, the voltage at V+ is inverted to -2VIN and stored at the V- reservoir capacitor. The voltages at V+ and V- are then linear regulated and appear at POUT and NOUT, respectively. The ripple noise induced by the doubling and inverting charge pump is reduced by the linear regulators to 1.2mVp-p for POUT and 1.7mVp-p for NOUT. In addition, the linear regulator's excellent AC rejection attenuates noise from the incoming supply. A minimum of 5mA is available at each output. When NOUT is more negative than 90% of the regulated output voltage, the open-drain RDY output pulls to GND. The charge pump operates in three modes: when SYNC = GND, the charge pump operates at 25kHz; when SYNC = IN, it operates at 100kHz, or SYNC can be overdriven with an external clock in the 20kHz to 240kHz range. The clock must have a 40% to 60% duty cycle.
__________Applications Information
Setting the Output Voltage
Connect SETP or SETN directly to GND to select a fixed +5V or -5V output voltage, respectively (Figure 2). Select an alternative voltage for either output by connecting SETP or SETN to the midpoint of a resistor voltage divider from POUT or NOUT, respectively, to GND (Figure 3). (2 x VIN) must be 1.0V above the absolute value of the output voltage to ensure proper regulation. Calculate the output voltage from the formulas below. Choose R1 and R3 at between 100k to 400k. VPOUT R2 = R1 - 1 VPSET REF
()
VNOUT R4 = R3 - 1 VNSET REF
()
where VPSET REF = 1.25V (typical) and VNSET REF = -1.25V (typical).
_______________________________________________________________________________________
7
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies MAX768
Table 1. Shutdown-Control Logic
PSHDN
1 1 0 0
NSHDN
1 0 1 0
POUT STATUS Positive output active Positive output active Positive output inactive Shutdown (low-power mode)
NOUT STATUS Negative output active Negative output inactive Negative output active Shutdown (low-power mode)
SUPPLY CURRENT (mA) 0.8 0.7 0.3 0.0001
Table 2. Charge-Pump Capacitor Selection (Figure 2)
SYNC INPUT GND IN External Clock FREQUENCY (kHz) 25 100 20 to 240 CAPACITORS C1, C2, C3, C4 10F 2.2F C = 220F/f (kHz) 10F 4.7F C5, C6 C7
Shutdown
The MAX768 has two active-low, TTL logic-level shutdown inputs: PSHDN and NSHDN. When both inputs are pulled low, the MAX768 shuts down and the supply current is reduced to 10A max over temperature. Pulling PSHDN low turns off the positive linear regulator; the doubler charge pump remains active. Pulling the NSHDN input low while PSHDN remains high turns off the inverter charge pump, the negative linear regulator, and the output-ready indicator (Table 1).
VIN
C2
C1GND C2-
C2+ IN C1+ C3 V+
C1
Capacitors
The overall dropout voltage is a function of the charge pump's output resistance and the voltage drop across the linear regulator. The charge-pump output resistance is a function of the switching frequency and the capacitor's ESR value. Therefore, minimizing the charge-pump capacitors' ESR minimizes dropout voltage.
RPOUT = 84 + 8(C1ESR ) + (C3ESR ) + RNOUT = 84 + 8(C1ESR ) + 4(C2ESR ) + (C4ESR ) + 2 fOSCC1 + 1 fOSCC2 2 fOSCC1
C4
C7
V-
MAX768
NOUT SETN NSHDN PSHDN POUT SETP C5 RDY SYNC TO VIN C6 -5V +5V
See Table 2 for capacitor selection. All capacitors should be either surface-mount ceramic chip or tantalum. External capacitor values may be adjusted to optimize size, performance, and cost.
8
SEE TABLE 2 FOR CAPACITOR VALUES
Figure 2. MAX768 Standard Application Circuit
_______________________________________________________________________________________
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies MAX768
VPOUT = (1.25) (1+ VIN IN SYNC SETP C1+ R1 C1 C1C2+ C2 C2NSHDN PSHDN VGND C4 R3 V+ C3 POUT R2
R2 ) R1 GND C5
MAX768
MAX768
NOUT
SETN R4 NOUT VNOUT = (-1.25) (1 + RDY
C6
Figure 4. A Schottky diode protects the MAX768 when a large current flows from POUT to NOUT.
R4 ) R3
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 SETP and SETN. 3) Use a ground plane.
Figure 3. MAX768 Adjustable Configuration
Switching-Frequency Control
For applications sensitive to the MAX768's internal switching frequency, connect an external TTL/CMOS (within IN and GND) clock to SYNC. The clock must be a 20kHz to 240kHz square wave between 40% and 60% duty cycle.
Noise and Ripple Measurement
Accurately measuring output noise and ripple can be difficult. Brief differences in ground potential between the 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 output capacitor C3, C4, C5, or C6. Do not use the oscilloscope probe's ground lead; instead, remove the cover's ground lead and touch the ground ring on the probe directly to the ground terminal of C3, C4, C5, or C6. Or, use a Tektronix chassis-mount test jack (part no. 131-0258) to connect your scope probe directly. This direct connection provides the most accurate noise and ripple measurement.
Schottky Diodes
When under heavy loads, where POUT is sourcing into NOUT (i.e., load current flows from POUT to NOUT, rather than from supply to ground), do not allow NOUT to pull above ground. In applications where large currents from POUT to NOUT are likely, use a Schottky diode (1N5817) between GND and NOUT, with the anode connected to GND (Figure 4). Connect a IN5817-type Schottky diode from C2- to Vto assure proper start-up.
_______________________________________________________________________________________
9
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies MAX768
__________________Pin Configuration
TOP VIEW
C1- 1 GND 2 C2- 3 V- 4 NOUT 5 SETN 6 NSHDN 7 PSHDN 8 16 C2+ 15 IN 14 C1+
___________________Chip Information
TRANSISTOR COUNT: 657 SUBSTRATE CONNECTED TO GND
MAX768
13 V+ 12 POUT 11 SETP 10 RDY 9 SYNC
QSOP
10
______________________________________________________________________________________
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies
________________________________________________________Package Information
DIM INCHES MILLIMETERS MAX MIN MIN MAX 0.068 0.061 1.55 1.73 0.004 0.0098 0.127 0.25 0.061 0.055 1.40 1.55 0.012 0.008 0.20 0.31 0.0075 0.0098 0.19 0.25 SEE PIN COUNT VARIATIONS 0.157 0.150 3.81 3.99 0.25 BSC 0.635 BSC 0.244 0.230 5.84 6.20 0.016 0.010 0.25 0.41 0.035 0.016 0.41 0.89 SEE PIN COUNT VARIATIONS SEE PIN COUNT VARIATIONS 8 0 0 8 DIM PINS D S D S D S D S 16 16 20 20 24 24 28 28 INCHES MILLIMETERS MIN MAX MIN MAX 0.189 0.196 4.80 4.98 0.0020 0.0070 0.05 0.18 0.337 0.344 8.56 8.74 0.0500 0.0550 1.27 1.40 0.337 0.344 8.56 8.74 0.0250 0.0300 0.64 0.76 0.386 0.393 9.80 9.98 0.0250 0.0300 0.64 0.76
21-0055A
MAX768
D A e B
A1
S
A A1 A2 B C D E e H h L N S
E
H h x 45 A2
N E C L
QSOP QUARTER SMALL-OUTLINE PACKAGE
______________________________________________________________________________________
11
Low-Noise, Dual-Output, Regulated Charge Pump for GaAsFET, LCD, and VCO Supplies MAX768
NOTES
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 __________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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