View MAX680_1847.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-0896; Rev 1; 7/96
+5V to 10V Voltage Converters
________________General Description
The MAX680/MAX681 are monolithic, CMOS, dual charge-pump voltage converters that provide 10V outputs from a +5V input voltage. The MAX680/MAX681 provide both a positive step-up charge pump to develop +10V from +5V input and an inverting charge pump to generate the -10V output. Both parts have an on-chip, 8kHz oscillator. The MAX681 has the capacitors internal to the package, and the MAX680 requires four external capacitors to produce both positive and negative voltages from a single supply. The output source impedances are typically 150, providing useful output currents up to 10mA. The low quiescent current and high efficiency make this device suitable for a variety of applications that need both positive and negative voltages generated from a single supply. The MAX864/MAX865 are also recommended for new designs. The MAX864 operates at up to 200kHz and uses smaller capacitors. The MAX865 comes in the smaller MAX package.
____________________________Features
o 95% Voltage-Conversion Efficiency o 85% Power-Conversion Efficiency o +2V to +6V Voltage Range o Only Four External Capacitors Required (MAX680) o No Capacitors Required (MAX681) o 500A Supply Current o Monolithic CMOS Design
MAX680/MAX681
_______________Ordering Information
PART MAX680CPA MAX680CSA MAX680C/D MAX680EPA MAX680ESA MAX680MJA MAX681CPD MAX681EPD TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -55C to +125C 0C to +70C -40C to +85C PIN-PACKAGE 8 Plastic DIP 8 Narrow SO Dice 8 Plastic DIP 8 Narrow SO 8 CERDIP 14 Plastic DIP 14 Plastic DIP
________________________Applications
The MAX680/MAX681 can be used wherever a single positive supply is available and where positive and negative voltages are required. Common applications include generating 6V from a 3V battery and generating 10V from the standard +5V logic supply (for use with analog circuitry). Typical applications include: 6V from 3V Lithium Cell Hand-Held Instruments Data-Acquisition Systems Panel Meters 10V from +5V Logic Supply Battery-Operated Equipment Operational Amplifier Power Supplies
_________Typical Operating Circuits
+5V C1+ 4.7F VCC 4.7F +10V
_________________Pin Configurations
TOP VIEW
MAX680 V+ C1C1+
VC2- GND 4.7F
4.7F
C1- 1 C2+ 2 C2- 3 V- 4 8 V+ C1+ VCC GND V+ 1 C1- 2 C1- 3 C2+ 4 C2- 5 C2- 6 V- 7 14 VCC 13 VCC 12 VCC
-10V
GND +5V VCC FOUR PINS REQUIRED (MAX681 ONLY) V+
GND
MAX680
7 6 5
MAX681
11 VCC 10 V+ 9 8 GND GND
+10V
MAX681
GND V-10V GND
DIP/SO
GND +5V to 10V CONVERTER
DIP
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
+5V to 10V Voltage Converters MAX680/MAX681
ABSOLUTE MAXIMUM RATINGS
VCC ................................................................................... +6.2V V+ ...................................................................................... +12V V- ..........................................................................................-12V V- Short-Circuit Duration ...........................................Continuous V+ Current ..........................................................................75mA VCC V/T ..........................................................................1V/s Continuous Power Dissipation (TA = +70C) 8-Pin Plastic DIP (derate 9.09mW/C above +70C) . ....727mW 8-Pin Narrow SO (derate 5.88mW/C above +70C) .....471mW 8-Pin CERDIP (derate 8.00mW/C above +70C) ..........640mW 14-Pin Plastic DIP (derate 10.00mW/C above +70C) ...800mW Storage Temperature Range .............................-65C to +160C 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
(VCC = +5V, test circuit Figure 1, TA = +25C, unless otherwise noted.) PARAMETER CONDITIONS VCC = 3V, TA = +25C, RL = VCC = 5V, TA = +25C, RL = Supply Current VCC = 5V, 0C TA +70C, RL = VCC = 5V, -40C TA +85C, RL = VCC = 5V, -55C TA +125C, RL = Supply-Voltage Range MIN TA MAX, RL = 10k IL+ = 10mA, IL- = 0mA, VCC = 5V, TA = +25C Positive Charge-Pump Output Source Resistance IL+ = 5mA, IL- = 0mA, VCC = 2.8V, TA = +25C IL+ = 10mA, IL- = 0mA, VCC = 5V 0C TA +70C -40C TA +85C -55C TA +125C 90 110 2.0 1.5 to 6.0 150 180 MIN TYP 0.5 1 MAX 1 2 2.5 3 3 6.0 250 300 325 350 400 150 175 200 200 250 4 RL = 10k V+, RL = V-, RL = 95 90 8 85 99 97 kHz % % V mA UNITS
IL- = 10mA, IL+ = 0mA, V+ = 10V, TA = +25C Negative Charge-Pump Output Source Resistance IL- = 5mA, IL+ = 0mA, V+ = 5.6V, TA = +25C IL- = 10mA, IL+ = 0mA, V+ = 10V Oscillator Frequency Power Efficiency Voltage-Conversion Efficiency 0C TA +70C -40C TA +85C -55C TA +125C
2
_______________________________________________________________________________________
+5V to 10V Voltage Converters
__________________________________________Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
MAX680/MAX681
OUTPUT RESISTANCE vs. SUPPLY VOLTAGE
MAX680/681-TOC1
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX680/681-TOC2
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX680/681-TOC3
250 C1-C4 = 10F OUTPUT RESISTANCE () 200 ROUT+ 150
10 9 8 V- vs. IL+ IL- = 0
2.0
SUPPLY CURRENT (mA)
1.5
|VOUT| (V)
7 6 5 4
V+ vs. IL+ IL- = 0 V+ vs. ILIL+ = 0 V- vs. ILIL+ = 0
1.0
100 ROUT50 0 2.0 3.0 V 4.0 (V) 5.0 6.0
RL =
0.5
0 0 5 10 15 20 2.0 3.0 V 4.0 (V) 5.0 6.0 LOAD CURRENT ( A)
OUTPUT VOLTAGE vs. OUTPUT CURRENT (FROM V+ TO V-)
MAX680/681-TOC4
OUTPUT SOURCE RESISTANCE vs. TEMPERATURE
MAX680/681-TOC5
OUTPUT RIPPLE vs. OUTPUT CURRENT (IL+ OR IL-)
VCC = 5V MAX681 OUTPUT RIPPLE (mVp-p) 150 V+ 100 MAX680 C3, C4 = 10F 50 MAX680 C3, C4 = 100F V+ AND V15 20 VV+ VMAX681/681-TOC6
10 MAX680, MAX681 9 8
200 OUTPUT SOURCE RESISTANCE () VCC = 5V 150 ROUT+
200
|VOUT| (V)
7 V+ 6 5 C1-C4 = 10F 4 0 1 2 3 4 5 6 7 8 9 10 OUTPUT CURRENT (mA) V-
100 ROUT50
0 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
0 0 5 10 OUTPUT CURRENT (mA)
_______________________________________________________________________________________
3
+5V to 10V Voltage Converters MAX680/MAX681
_______________Detailed Description
VCC IN
C1 4.7F 1 2 C2 4.7F 3 4 C1C2+ C2V-
MAX680
V+ C1+ VCC GND 8 7 6 5 GND ILC4 10F RLV- OUT C3 10F IL+ R L+ V+ OUT
Figure 1. Test Circuit
The MAX681 contains all circuitry needed to implement a dual charge pump. The MAX680 needs only four capacitors. These may be inexpensive electrolytic capacitors with values in the 1F to 100F range. The MAX681 contains two 1.5F capacitors as C1 and C2, and two 2.2F capacitors as C3 and C4. See Typical Operating Characteristics. Figure 2a shows the idealized operation of the positive voltage converter. The on-chip oscillator generates a 50% duty-cycle clock signal. During the first half of the cycle, switches S2 and S4 are open, S1 and S3 are closed, and capacitor C1 is charged to the input voltage VCC. During the second half-cycle, S1 and S3 are open, S2 and S4 are closed, and C1 is translated upward by VCC volts. Assuming ideal switches and no load on C3, charge is transferred onto C3 from C1 such that the voltage on C3 will be 2VCC, generating the positive supply. Figure 2b shows the negative converter. The switches of the negative converter are out of phase from the positive converter. During the second half of the clock cycle, S6 and S8 are open and S5 and S7 are closed, charging C2 from V+ (pumped up to 2VCC by the positive charge pump) to GND. In the first half of the clock
a)
V+ S1 VCC C1 C3 C1+ S2
b)
V+ S5 C2+ S6 GND I L+ RL+ C2 ILC4 S3 GND C1S4 VCC GND C2S7 S8 VRL-
8kHz
Figure 2. Idealized Voltage Quadrupler: a) Positive Charge Pump; b) Negative Charge Pump
4 _______________________________________________________________________________________
+5V to 10V Voltage Converters
cycle, S5 and S7 are open, S6 and S8 are closed, and the charge on C2 is transferred to C4, generating the negative supply. The eight switches are CMOS power MOSFETs. S1, S2, S4, and S5 are P-channel switches, while S3, S6, S7, and S8 are N-channel switches.
________________________Applications
Positive and Negative Converter
The most common application of the MAX680/MAX681 is as a dual charge-pump voltage converter that provides positive and negative outputs of two times a positive input voltage. For applications where PC board space is at a premium, the MAX681, with its capacitors internal to the package, offers the smallest footprint. The simple circuit shown in Figure 3 performs the same function using the MAX680 with external capacitors C1 and C3 for the positive pump and C2 and C4 for the negative pump. In most applications, all four capacitors are low-cost, 10F or 22F polarized electrolytics. When using the MAX680 for low-current applications, 1F can be used for C1 and C2 charge-pump capacitors, and 4.7F for C3 and C4 reservoir capacitors. C1 and C3 must be rated at 6V or greater, and C2 and C4 must be rated at 12V or greater.
MAX680/MAX681
__________Efficiency Considerations
Theoretically, a charge-pump voltage multiplier can approach 100% efficiency under the following conditions: * The charge-pump switches have virtually no offset and extremely low on-resistance * Minimal power is consumed by the drive circuitry * The impedances of the reservoir and pump capacitors are negligible For the MAX680/MAX681, the energy loss per clock cycle is the sum of the energy loss in the positive and negative converters as below: LOSSTOT = LOSSPOS + LOSSNEG = 12 C1 [(V+)2 - (V+)(VCC)] +
1 2
C2
[(V+)2 - (V-)2]
C1 22F 1 2 C2 22F 3 4 C1C2+ C2V-
There will be a substantial voltage difference between (V+ - V CC ) and V CC for the positive pump, and between V+ and V-, if the impedances of pump capacitors C1 and C2 are high relative to their respective output loads. Larger C3 and C4 reservoir capacitor values reduce output ripple. Larger values of both pump and reservoir capacitors improve efficiency.
MAX680
V+ C1+ VCC GND 8 7 6 5 GND C4 22F V- OUT C3 22F VCC IN V+ OUT
________Maximum Operating Limits
The MAX680/MAX681 have on-chip zener diodes that clamp VCC to approximately 6.2V, V+ to 12.4V, and V- to -12.4V. Never exceed the maximum supply voltage: excessive current may be shunted by these diodes, potentially damaging the chip. The MAX680/ MAX681 operate over the entire operating temperature range with an input voltage of +2V to +6V.
Figure 3. Positive and Negative Converter
_______________________________________________________________________________________
5
+5V to 10V Voltage Converters MAX680/MAX681
22F 1 2 22F 3 4 C2VVCC GND 6 5
22F
MAX680
C1C2+ V+ C1+
8 7 22F
1 2 3 4
MAX680
C1C2+ C2VV+ C1+ VCC GND
8 7 6 5 22F
V+ OUT
VCC IN GND 22F
V- OUT
Figure 4. Paralleling MAX680s For Lower Source Resistance
The MAX680/MAX681 are not voltage regulators: the output source resistance of either charge pump is approximately 150 at room temperature with VCC at 5V. Under light load with an input VCC of 5V, V+ will approach +10V and V- will be at -10V. However both, V+ and V- will droop toward GND as the current drawn from either V+ or V- increases, since the negative converter draws its power from the positive converter's output. To predict output voltages, treat the chips as two separate converters and analyze them separately. First, the droop of the negative supply (VDROP-) equals the current drawn from V- - (IL-) times the source resistance of the negative converter (RS-): VDROP - = IL- x RSLikewise, the positive supply droop (VDROP+) equals the current drawn from the positive supply (IL+) times the positive converter's source resistance (RS+), except that the current drawn from the positive supply is the sum of the current drawn by the load on the positive supply (IL+) plus the current drawn by the negative converter (IL-): (VDROP+) = IL+ x RS+ = (IL+ + IL-) x RS+
The positive output voltage will be: V+ = 2VCC - VDROP+ The negative output voltage will be: V- = (V+ - VDROP) = - (2VCC - VDROP + - VDROP-) The positive and negative charge pumps are tested and specified separately to provide the separate values of output source resistance for use in the above formulas. When the positive charge pump is tested, the negative charge pump is unloaded. When the negative charge pump is tested, the positive supply V+ is from an external source, isolating the negative charge pump. Calculate the ripple voltage on either output by noting that the current drawn from the output is supplied by the reservoir capacitor alone during one half-cycle of the clock. This results in a ripple of: VRIPPLE = 12IOUT (1 fPUMP)(1 CR) For the nominal fPUMP of 8kHz with 10F reservoir capacitors, the ripple will be 30mV with IOUT at 5mA. Remember that in most applications, the positive charge pump's IOUT is the load current plus the current taken by the negative charge pump.
6
_______________________________________________________________________________________
+5V to 10V Voltage Converters
Paralleling Devices
Paralleling multiple MAX680/MAX681s reduces the output resistance of both the positive and negative converters. The effective output resistance is the output resistance of a single device divided by the number of devices. As Figure 4 shows, each MAX680 requires separate pump capacitors C1 and C2, but all can share a single set of reservoir capacitors. no external setting resistors, minimizing part count. The combined quiescent current of the MAX680/MAX681, MAX663, and MAX664 is less than 500A, while the output current capability is 5mA. The MAX680/MAX681 input can vary from 3V to 6V without affecting regulation appreciably. With higher input voltage, more current can be drawn from the MAX680/MAX681 outputs. With 5V at VCC, 10mA can be drawn from both regulated outputs simultaneously. Assuming 150 source resistance for both converters, with (IL+ + IL-) = 20mA, the positive charge pump will droop 3V, providing +7V for the negative charge pump. The negative charge pump will droop another 1.5V due to its 10mA load, leaving -5.5V at Vsufficient to maintain regulation for the MAX664 at this current.
MAX680/MAX681
5V Regulated Supplies from a Single 3V Battery
Figure 5 shows a complete 5V power supply using one 3V battery. The MAX680/MAX681 provide +6V at V+, which is regulated to +5V by the MAX666, and -6V, which is regulated to -5V by the MAX664. The MAX666 and MAX664 are pretrimmed at wafer sort and require
LOW-BATTERY WARNING AT 3.5V LBO LBI 2M 100F VCC 6V TO 3V 100F C1C2+ 100F C2GND 100F VIN -12V TO -6V V0.1F GND SDN VSET 10F GND C1+ MAX680 V+ 1.2M 0.1F +12V TO +6V VIN GND VOUT SDN VSET 10F +5V SENSE
MAX666
MAX664
VOUT1 VOUT2 SENSE -5V
Figure 5. Regulated +5V and -5V from a Single Battery
_______________________________________________________________________________________
7
+5V to 10V Voltage Converters MAX680/MAX681
___________________Chip Topography
C1C2+ V+
C1+
0.116" (2.95mm)
V CC C2-
V-
GND
0.72" (1.83mm)
________________________________________________________Package Information
DIM INCHES MAX MIN 0.069 0.053 0.010 0.004 0.019 0.014 0.010 0.007 0.157 0.150 0.050 0.244 0.228 0.050 0.016 MILLIMETERS MIN MAX 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 3.80 4.00 1.27 5.80 6.20 0.40 1.27
D A e B
0.101mm 0.004in.
0-8
A1
C
L
A A1 B C E e H L
E
H
Narrow SO SMALL-OUTLINE PACKAGE (0.150 in.)
DIM PINS D D D 8 14 16
INCHES MILLIMETERS MIN MAX MIN MAX 0.189 0.197 4.80 5.00 0.337 0.344 8.55 8.75 0.386 0.394 9.80 10.00
21-0041A
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.
8 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1989 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX680

	To Download MAX680 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .