SP682CP

SP682 Corporation Micro Power Inverting Charge Pump ■ Low Power Voltage Conversion ■ +2.4V to +5.5V Input Range ■ 99% Voltage Conversion Efficiency ■ Typical 60µA Supply Current ■ Requires Only Three External Capacitors ■ Includes Low Power Shutdown Option ■ Ideal in Portable Applications Such As Handheld Instruments Cellular Phones Personal Digital Assistants Laptops and Notebooks ■ Pin Compatible Upgrade to Microchip's TC682 C1- 1 C2+ 2 C2- 3 VOUT 4 8 SD SP682 8 Pin MSOP 7 C1+ 6 VCC 5 GND APPLICATIONS ■ LCD Display ■ Negative bias supply for op amps ■ Serial interface protocol circuits DESCRIPTION The SP682 is a monolithic charge pump voltage converter that produces a doubled, negative voltage from a single positive supply. The SP682 charge pump outputs a –10V voltage from a +5V input. Three external charge pump capacitors are required to support the voltage conversion and voltage doubling process. An internal oscillator generates a 12kHz clock which cycles the internal switching that charges the storage and transfer capacitors. The charge pump architecture is fabricated using a low power BiCMOS process technology. The SP682 charge pump is ideal for low power applications requiring a typical +3V battery source such as a lithium cell. Typical applications are handheld instruments, notebook and laptop computers, cellular phones, and data acquisition or GP systems. The SP682 is packaged in either 8-pin NSOIC, 8-pin MSOP for surface mount applications, and 8 Pin PDIP. TYPICAL APPLICATION CIRCUIT +2.4V to +5V 1µF + 6 7 C1 1 2 C1– C2+ C1+ VCC VOUT 4 - VOUT COUT SP682 SD GND 5 8 C2 3 C2– Date: 5/20/04 SP682 Micro Power Inverting Charge Pump © Copyright 2004 Sipex Corporation 1 ABSOLUTE MAXIMUM RATINGS These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. VCC...........................................................................+7V VOUT........................................................................–11V Storage Temperature..........................-65˚C to +150˚C Power Dissipation: 8-pin NSOIC......................................500mW 8-pin MSOP......................................320mW 8-pin PDIP......................................750mW Package Derating: 8-pin NSOIC: øJA..................................................128 °C/W 8-pin MSOP: øJA..................................................216°C/W 8-pin PDIP: øJA..................................................97°C/W ELECTRICAL CHARACTERISTICS TA = TMIN to TMAX and VCC = +5V. Charge pump cap = 3.3µF, unless otherwise noted. MIN. SUPPLY CURRENT ICC in shutdown CHARGE PUMP OUTPUT VOUT SOURCE RESISTANCE ROUT OSCILLATOR FREQUENCY fOSC CONVERSION EFFICIENCY VOUT EFF VOUT EFF START-UP TIMING VOUT Power On Delay SHUTDOWN TIMING Shutdown to VOUT Delay SUPPLY VOLTAGE VCC Operating Temperature Range -C -E TYP. 60 MAX. 120 200 1 UNITS µA µA µA CONDITIONS CHARGE PUMP CAPACITORS: 3.3µ F RL = ∞, TA = +25°C RL = ∞ TA = +25 C, SD = +5V O CHARGE PUMP CAPACITORS: 3.3µ F –9.9 –9.0 –9.99 –9.5 140 380 12 180 230 450 20 Volts Volts Ω Ω Ω kHz RL = ∞ RL = 2kΩ IL = 10mA, TA = +25°C IL = 10mA IL = 5mA, VCC = +2.8V fosc = 2 X fC1+ 99 90 99.9 95 12 % % ms RL = ∞ RL = 2kΩ RL = 2kΩ 5 ms RL = 2kΩ +2.4 +5.5 Volts 0 -40 +70 +85 oC oC Date: 5/20/04 SP682 Micro Power Inverting Charge Pump © Copyright 2004 Sipex Corporation 2 THEORY OF OPERATION The SP682's charge pump design is a simplified version of Sipex's original patented charge pump design (5,306,954) except that it only generates a negative output. The charge pump utilizes external capacitors to store the charge. Figure 1 shows the waveform found on the negative side of capacitor C2. There is a free– running oscillator, running at 12kHz, that controls the two phases of the voltage shifting. A description of each phase follows. Phase 1 VOUT charge storage — During this phase of the clock cycle, the positive side of capacitors C1 and C2 are initially charged to +5V. Cl+ is then switched to ground and the charge on C1– is transferred to C2–. Since C2+ is connected to +5V, the voltage potential across capacitor C2 is now 10V. Phase 2 VOUT transfer — Phase two of the clock connects the negative terminal of C2 to the VOUT storage capacitor and the positive terminal of C2 to ground, and transfers the generated –l0V to C3. Simultaneously, the positive side of capacitor C 1 is switched to +5V and the negative side is connected to ground. The oscillator frequency or clock rate for the charge pump is designed for low power operation. The oscillator operates at a frequency of C1 + – about 12kHz (20kHz maximum) which conserves power as opposed to higher frequency which operation typically draws more power from VCC. The external charge pump capacitors specified are 3.3µF but the absolute minimum should be 1µF. EFFICIENCY INFORMATION A charge pump theoretically produces a doubled voltage at 100% efficiency. However in the real world, there is a small voltage drop on the output which reduces the output efficiency. The SP682 can usually run 99.9% efficient without driving a load. While driving a 1kΩ load, the SP682 remains over 90% efficiency. Output Voltage Efficiency = VOUT / (–2*VCC); VOUT = –2*VCC + VDROP VDROP = (IOUT)*(ROUT) Power Loss = IOUT*(VDROP) The efficiency changes as the external charge pump capacitors are varied. Larger capacitor values will strengthen the output and reduce output ripple. Although smaller capacitors will cost less and save board space, lower values will reduce the output drive capability and also increase the output ripple. VCC = +5V +5V C2 + – –5V –5V VOUT Storage Capacitor – + C3 Figure 2. Charge Pump Phase 1 VCC = +5V C1 + – C2 + – VOUT Storage Capacitor – + –10V C3 Figure 1. Charge Pump Waveform Figure 3. Charge Pump Phase 2 Date: 5/20/04 SP682 Micro Power Inverting Charge Pump © Copyright 2004 Sipex Corporation 3 THEORY OF OPERATION The ESR of the charge pump capacitors also determine the output resistance. Assuming that switch resistances are approximately equal, the output resistance can be derived as shown below: ROUT = 16*(RSW1-4) + 4*( ESRC1+ ESRC2) + ESRC3 + 1 / (fOSC * C1) + 1 / (fOSC * C2) ROUT is typically 140Ω at +25°C with VCC at +5V using 3.3µF capacitors. The total internal switch resistance (16*RSW) is approximately 90Ω. The table below shows the comparison of ROUT versus C1&C2. C1, C2 (µF) 0.05 0.10 0.47 1.00 3.30 4.70 10.00 22.00 Table 1. ROUT .vs. C1, C2 ROUT (Ω) 4085 2084 510 285 140 125 105 94 SHUTDOWN FEATURE The SP682 charge pump includes a shutdown feature (pin 8) which disables the charge pump when the VOUT is not needed. A logic "1" will activate the shutdown mode. If shutdown is not needed, it can be left open where an internal pull-down resistor will always keep the charge pump active. Typical input current for the shutdown pin is 3µA. The shutdown feature is another option for conserving power in portable applications, reducing current to only 1µA. PARALLEL DEVICES Multiple SP682 charge pumps can be connected in parallel. However, the effective output resistance now is the output resistance of a single device divided by the number of devices. Connecting multiple pumps allows the user to save on the storage capacitor. The charge pump capacitors still must be separate for each device. APPLICATIONS INFORMATION The SP682 charge pump produces a doubled, inverted voltage from the VCC input. As such, it can serve in many applications where a negative –5V to –10V output is needed. Typical applications include powering analog switches, and biasing LCD displays and panels. The output voltage ripple is also affected by the capacitors, specifically COUT. Larger values will reduce the output ripple for a given output current load of current. The formula representation is: VRIPPLE = {1 / [2 * (fOSC * C3)] + 2 * (ESRC3)} * IOUT To minimize the output ripple, the COUT storage capacitor can be increased to over 10µF whereas the pump capacitors can range from 1µF to 5µF. Table 2 shows the typical VRIPPLE for given COUT values. COUT (µF) 0.50 1.00 3.30 4.70 10.00 22.00 Table 2. C3 .vs. VRIPPLE VRIPPLE (mV) 1020 520 172 120 70 43 Date: 5/20/04 SP682 Micro Power Inverting Charge Pump © Copyright 2004 Sipex Corporation 4 PACKAGE: 8 PIN NSOIC D e E/2 E1 E E1/2 SEE VIEW C 1 INDEX AREA (D/2 X E1/2) A b Ø1 TOP VIEW Gauge Plane L2 Seating Plane Ø1 L L1 Ø VIEW C A A2 SEATING PLANE A1 SIDE VIEW 8 Pin NSOIC (JEDEC MS-012, AA - VARIATION) DIMENSIONS Minimum/Maximum (mm) WITH PLATING b COMMON HEIGHT DIMENSION SYMBOL A A1 A2 b c D E E1 e L L1 L2 Ø Ø1 MIN NOM MAX 1.75 1.35 0.25 0.10 1.25 1.65 0.31 0.51 0.17 0.25 4.90 BSC 6.00 BSC 3.90 BSC 1.27 BSC 0.40 1.27 1.04 REF 0.25 BSC 0º 8º 5º 15º c BASE METAL CONTACT AREA PACKAGE: 8 PIN NSOIC Date: 5/20/04 SP682 Micro Power Inverting Charge Pump © Copyright 2004 Sipex Corporation 5 PACKAGE: 8 PIN MSOP D e1 Ø1 E/2 R1 R Gauge Plane L2 Seating Plane 1 2 E E1 Ø1 L L1 Ø e Pin #1 indentifier must be indicated within this shaded area (D/2 * E1/2) 8-PIN MSOP JEDEC MO-187 (AA) Variation A A1 A2 b c D E E1 e e1 L L1 L2 N R R1 Ø Ø1 Dimensions in (mm) MIN 0 0.75 0.22 0.08 NOM MAX 0.85 3.00 BSC 4.90 BSC 3.00 BSC 0.65 BSC 1.95 BSC 0.40 0.60 0.95 REF 0.25 BSC 0.07 0.07 0º 0º 8 8º 15º 0.80 1.10 0.15 0.95 0.38 0.23 B B A2 b A1 WITH PLATING A (b) c Section B-B BASE METAL 1 8-PIN MSOP Date: 5/20/04 SP682 Micro Power Inverting Charge Pump © Copyright 2004 Sipex Corporation 6 PACKAGE: 8 PIN PDIP N INDEX AREA E1 E 123 N/2 D A1 A D1 8 PIN PDIP JEDEC MS-001 (BA) Variation A A1 A2 b b2 b3 c D D1 E E1 e eA eB L .115 A2 b3 e b2 b L Dimensions in inches MIN .015 .115 .014 .045 .030 .008 .355 .005 .300 .240 NOM MAX .130 .018 .060 .039 .010 .365 .310 .250 .100 BSC .300 BSC .130 .430 .150 .210 .195 .022 .070 .045 .014 .400 .325 .280 E c eA eB b c 8 PIN PDIP Date: 5/20/04 SP682 Micro Power Inverting Charge Pump © Copyright 2004 Sipex Corporation 7 ORDERING IFORMATION Part Number Temperature Range Package Types SP682CN ............................................. -0°C to +70°C ................................................................. 8-pin NSOIC SP682CN/TR ....................................... -0°C to +70°C ................................................................. 8-pin NSOIC SP682CP ............................................. -0°C to +70°C .................................................................... 8-pin PDIP SP682CU ............................................. -0°C to +70°C .................................................................. 8-pin MSOP SP682CU/TR ....................................... -0°C to +70°C .................................................................. 8-pin MSOP SP682EN ........................................... -40°C to +85°C ................................................................. 8-pin NSOIC SP682EN/TR ..................................... -40°C to +85°C ................................................................. 8-pin NSOIC SP682EP ........................................... -40°C to +85°C .................................................................... 8-pin PDIP SP682EU ........................................... -40°C to +85°C .................................................................. 8-pin MSOP SP682EU/TR ..................................... -40°C to +85°C .................................................................. 8-pin MSOP /TR = Tape and Reel Pack quantity is 2,500 for NSOIC and MSOP. Corporation ANALOG EXCELLENCE Sipex Corporation Headquarters and Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600 Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others. Date: 5/20/04 SP682 Micro Power Inverting Charge Pump © Copyright 2004 Sipex Corporation 8