SP6830 SIPEX | Alldatasheet
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Technical content
Rev. 9-22-00 SP6830/6831 Low Power Voltage Inverters With Shutdown © Copyright 2000 Sipex Corporation
FEATURES
I 99.9% Voltage Conversion Efficiency I +1.15V to +5.3V Input Voltage Range I Inverts Input Supply Voltage I 70µA Supply Current for the SP6830 I 200µA Supply Current for the SP6831 I 35kHz Operating Frequency for the SP6830 I 120kHz Operating Frequency for the SP6831 I <1µA Shutdown Current I 6-pin SOT23-6 Package I Ideal for +3.6V Lithium Ion Battery
Applications
I Reverse +3.6V Lithium Ion Battery Protection I 25mA Output Current I 19Ω Output Resistance Low Power Voltage Inverters With Shutdown SP6830/6831
DESCRIPTION
The SP6830/6831 devices are CMOS Charge Pump Voltage Inverters that can be imple- mented into designs which require a negative voltage from a battery voltage source as low as +1.15V or a power supply rail voltage as high as +5.3V. The SP6830/6831 devices are ideal for both battery-powered and board level voltage conversion applications with a typical operating current of 70µA for the SP6830 and 200µA for the SP6831. These devices combine an ultra-low shutdown current of <1 µA with high efficiency (>95% over most of its load-current range) which are ideal for designs using batteries such as cell phones, PDAs, medical instruments, and other portable equipment. The SP6830/6831 devices are available in a space-saving 6-pin SOT23-6 Package. C1- VOUT VIN C1+ GND SP6830 SP6831 SHDN5 I Small LCD Negative Bias Voltage I Power Amplifier Negative Bias Voltage I +5V to -5V Voltage Conversion
Rev. 9-22-00 SP6830/6831 Low Power Voltage Inverters With Shutdown © Copyright 2000 Sipex Corporation SPECIFICATIONS VIN = +5V, C1=C2=C3=3.3µF for the SP6830 , C1=C2=C3=1µF for the SP6831 , and TAMB =-40°C to +85°C unless otherwise noted. Typical values are taken specifically at TAMB =+25°C. Note 1: Minimum VIN required for VO = -VIN +0.2V. Note 2: During the shutdown mode, VIN is disconnected from VOUT. Note 3: Capacitors are approximately 20% of the output impedance where ESR = fOSC x C . Note 4: Power Efficiency (Ideal) = V OUT x IOUT -VIN x (-VIN/RL) Note 5: Power Efficiency (Actual) = V OUT x IOUT V IN x IIN 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. V Power Dissipation Per Package RETEMARAP. NIM. PYT. XAMS TINUS NOITIDNOC V,egnaRegatloVylppuS DD 51.13 .5V R L k1= Ω I,tnerruCylppuS NIV 07 002 051 004 µA 0386PS 1386PS egatloVpu-tratSdeetnarauG8 .1V R L k1= Ω 1ETON, egatloVtupnInwodtuhS HGIH WOL 5.1V NI 5.0 VV NI V= NIM Vot XAM V NI V= NIM Vot XAM tnerruCylppuSnwodtuhS1 .00 .1 µA V,DNG=NDHS NI 2ETON,V5= f,ycneuqerFrotallicsO CSO 5.42 021 3.65 002 zHk 0386PS 1386PS ecnatsiseRtuptuO9 15 4 Ω I TUO 3ETON,Am52otAm5= ycneiciffEnoisrevnoCegatloV5 99 .99% R L nepo= )laedI(ycneiciffErewoP8 9% R L k1= Ω 4ETON, )lautcA(ycneiciffErewoP6 9% R L k1= Ω 5ETON,
Pin 1— VOUT — Inverting charge pump output. Pin 4 — GND — Ground reference. Figure 1. Voltage Inverter Circuit for the SP6830/6831
2 VIN
5 SHDN
4 GND
Rev. 9-22-00 SP6830/6831 Low Power Voltage Inverters With Shutdown © Copyright 2000 Sipex Corporation Figure 17: SP6830/6831 Connected as a Voltage Inverter in its Typical Operating Circuit; this Circuit Was Used to Obtain the Typical Performance Characteristics Found in Figures 2 Through 16 (unless otherwise noted) C1- VIN C1+ GND SP6830 SP6831 4R L VOUT
Rev. 9-22-00 SP6830/6831 Low Power Voltage Inverters With Shutdown © Copyright 2000 Sipex Corporation The SP6830/6831 devices are CMOS Charge Pump Voltage Converters that can be used to invert a +1.15V to +5.3V input voltage. These devices are ideal for designs involving battery- powered and/or board level voltage conversion applications. The typical operating frequency of the SP6830 is 35kHz. The typical operating frequency of the SP6831 is 120kHz. The SP6830 has a typical operating current of 70µA and the SP6831 operates at 200µA. Both devices can output 25mA with a voltage drop of 500mV. The devices are ideal for LCD panel bias applications, cellular phones, pagers, PDAs, medical instruments, and other portable battery-powered equipment. The SP6830/6831 devices combine a high efficiency (>95% over most of its load- current range) with a low quiescent current. THEORY OF OPERATION The SP6830/6831 devices should theoretically produce an inverted input voltage. In real world applications, there are small voltage drops at the output that reduce efficiency. The circuit of an ideal voltage inverter can be found in Figure 18. The voltage inverters require two external capacitors to store the charge. A description of the two phases follows: Phase 1 In the first phase of the clock cycle, switches S2 and S4 are opened and S1 and S3 closed. This connects the flying capacitor, C1, from V IN to ground. C1 charges up to the input voltage applied at VIN. Phase 2 In the second phase of the clock cycle, switches S1 and S3 are opened and S2 and S4 are closed. This connects the flying capacitor, C1, in parallel with the output capacitor, C2. The charge stored in C1 is now transferred to C2. Simultaneously, the negative side of C2 is connected to V OUT and the positive side is connected to ground. With the voltage across C2 smaller than the voltage across C1, the charge flows from C1 to C2 until the voltage at the V OUT equals -VIN. Charge-Pump Output The output of the SP6830/6831 devices is not regulated and therefore is dependent on the output resistance and the amount of load current. As the load current increases, losses may slightly increase at the output and the voltage may become slightly more positive. The loss at the negative output, V LOSS , equals the current draw, IOUT , from V OUT times the negative converter's source resistance, RS: V LOSS = IOUT x RS. The actual inverted output voltage at VOUT will equal the inverted voltage difference of VIN and V LOSS : V OUT = -(VIN - VLOSS ). Efficiency Theoretically, the total power loss of a switched capacitor voltage converter can be summed up as follows: ∑ PLOSS = PINT + PCAP + PCONV , where PLOSS is the total power loss, PINT is the total internal loss in the IC including any losses in the MOSFET switches, PCAP is the resistive loss of the charge pump capacitors, and PCONV is the total Figure 18. Circuit for an Ideal Voltage Inverter
efficiency of the SP6830/6831 devices in designs. on resistance of the internal MOSFET switches. capacitor circuit as seen in Figure 19. IIN is the supply input current. Figure 19. Equivalent Circuit for an Ideal Switched
Rev. 9-22-00 SP6830/6831 Low Power Voltage Inverters With Shutdown © Copyright 2000 Sipex Corporation and POUT is the the power output. Both efficiencies are provided to designers for comparison.
APPLICATION INFORMATION
For the following applications, C1 = C2 = C3 = 3.3µF for the SP6830 and C1 = C2 = C3 = 1.0µF for the SP6831. Capacitor Selection Low ESR capacitors are needed to obtain low output resistance. Refer to Table 1 for some suggested low ESR capacitors. The output resistance of the SP6830/6831 devices is a function of the ESR of C1 and C2. This output resistance can be determined by the equation previously provided in the Efficiency section: R OUT ≈ 4 x (2 x RSWITCHES + ESRC1 ) + ESRC2 + 1 fOSC x C1 , where ROUT is the circuit's output resistance, R SWITCHES is the internal resistance of the MOSFET switches, ESRC1 and ESRC2 are the ESR of their respective capacitors, and fOSC is the oscillator frequency. This term with fOSC is derived from an ideal switched-capacitor circuit as seen in Figure 19. Minimizing the ESR of C1 and C2 will minimize the total output resistance and will improve the efficiency. Flying Capacitor Decreasing flying capacitor, C1, values will increase the output resistance of the SP6830/ 6831 devices while increasing C1 will reduce the output resistance. There is a point where increasing C1 will have a negligible effect on the output resistance due to the the domination of the output resistance by the internal MOSFET switch resistance and the total capacitor ESR. Output Capacitor Increasing output capacitor, C2, values will decrease the output ripple voltage. Reducing the ESR of C2 will reduce both output ripple voltage and output resistance. If higher output ripple can be tolerated in designs, smaller capacitance values for C2 should be used with light loads. The following equation can be used to calculate the peak-to-peak ripple voltage: V RIPPLE = 2 x IOUT x ESRC2 + IOUT fOSC x C2. Input Bypass Capacitor The bypass capacitor at the input voltage will reduce AC impedance and the impact of any of the SP6830/6831 device's switching noise. It is recommended that for heavy loads a bypass capacitor approximately equal to the flying capacitor, C1, be used. For light loads, the value of the bypass capacitor can be reduced. Table 1. Suggested Low ESR Surface Mount Capacitors
Figure 23. SP6830/6831 Device Connected in a Doubler/Inverter Combination Circuit VOUT2 = inverted output voltage.
Rev. 9-22-00 SP6830/6831 Low Power Voltage Inverters With Shutdown © Copyright 2000 Sipex Corporation PACKAGE: SOT23-6 SYMBOL A b C D E L e a 1.45 0.15 1.30 0.50 0.20 3.10 3.00 1.75 0.55 O 0.90 0.00 0.90 0.25 0.09 2.80 2.60 1.50 0.35 O MIN MAX 0.95ref 1.90ref E A e CLb D CL A A .10 CL E1 L 2 0.20 DATUM 'A ' C a
Rev. 9-22-00 SP6830/6831 Low Power Voltage Inverters With Shutdown © Copyright 2000 Sipex Corporation
ORDERING INFORMATION
Model Temperature Range Package Type 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. Please consult the factory for pricing and availability on a Tape-On-Reel option. SIGNAL PROCESSING EXCELLENCE Corporation Sipex Corporation Headquarters and Sales Office
22 Linnell Circle
Billerica, MA 01821 TEL: (978) 667-8700 FAX: (978) 670-9001 e-mail: sales@sipex.com Sales Office
233 South Hillview Drive
Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600