TCM828 TCM829 Switched Capacitor Voltage Converters FEATURES GENERAL DESCRIPTION ■ ■ ■ ■ ■ ■ ■ The TCM828/829 are CMOS “charge-pump” voltage converters in ultra-small 5-Pin SOT-23A packages. They invert and/or double an input voltage which can range from +1.5V to +5.5V. Conversion efficiency is typically >95%. Switching frequency is 12kHz for the TCM828 and 35kHz for the TCM829. External component requirement is only two capacitors (3.3µF nominal) for standard voltage inverter applications. With a few additional components a positive doubler can also be built. All other circuitry, including control, oscillator, power MOSFETs are integrated on-chip. Supply current is 50µA (TCM828) and 115µA (TCM829). The TCM828 and TCM829 are available in a 5-Pin SOT-23A surface mount package. Charge Pump in 5-Pin SOT-23A Package >95% Voltage Conversion Efficiency Voltage Inversion and/or Doubling Low 50µA (TCM828) Quiescent Current Operates from +1.5V to +5.5V Up to 25mA Output Current Only Two External Capacitors Required APPLICATIONS ■ ■ ■ ■ ■ LCD Panel Bias Cellular Phones Pagers PDAs, Portable Dataloggers Battery-Powered Devices PIN CONFIGURATION ORDERING INFORMATION *5-Pin SOT-23A OUT 5 1 C+ Part No. Package Temp. Range TCM828ECT TCM829ECT 5-Pin SOT-23A 5-Pin SOT-23A – 40°C to +85°C – 40°C to +85°C NOTE: 5-Pin SOT-23A is equivalent to EIAJ SC-74A. VIN 2 C– 3 TCM828ECT TCM829ECT 4 GND NOTE: *5-Pin SOT-23A is equivalent to EIAJ SC-74A TYPICAL OPERATING CIRCUIT Voltage Inverter C+ VIN INPUT OUT V– OUTPUT C1 C– TCM828 TCM829 GND C2 © 2001 Microchip Technology Inc. DS21488A TCM828/829-4 5/22/00 Switched Capacitor Voltage Converters TCM828 TCM829 Power Dissipation (TA ≤ 70°C) 5-Pin SOT-23A ...............................................240mW Storage Temperature (Unbiased) ......... – 65°C to +150°C Lead Temperature (Soldering, 10 sec) ................. +300°C ABSOLUTE MAXIMUM RATINGS* Input Voltage (VIN to GND) ......................... +6.0V, – 0.3V Output Voltage (OUT to GND) .................... –6.0V, + 0.3V Current at OUT Pin .................................................. 50mA Short-Circuit Duration – OUT to GND ................ Indefinite Operating Temperature Range ............... – 40°C to +85°C *This is a stress rating only and functional operation of the device at these or any other conditions above 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: TA = 0°C to +85°C, VIN = +5V, C1 = C2 = 10µF (TCM828), C1 = C2 = 3.3µF (TCM829), unless otherwise noted. Typical values are at TA = +25°C. Symbol Parameter Device Test Conditions Min Typ Max Unit IDD Supply Current TCM828 TCM829 TA = +25°C Minimum Supply Voltage Maximum Supply Voltage Oscillator Frequency RLOAD = 10kΩ: TA = 0°C to +85°C 50 115 — 90 260 — µA V+ — — 1.5 RLOAD = 10kΩ — — 5.5 V 8.4 24.5 — 95 12 35 96 99.9 15.6 45.5 — — kHz — — 25 — 50 65 Ω V+ FOSC PEFF VEFF TCM828 TCM829 Power Efficiency Voltage Conversion Efficiency Output Resistance ROUT TA = +25°C ILOAD = 3mA, TA = +25°C RLOAD = ∞ IOUT = 5mA, TA = 25°C TA = 0°C to +85°C V % % NOTE: 1. Capacitor contribution is approximately 20% of the output impedance [ESR = 1 / pump frequency x capacitance)]. ELECTRICAL CHARACTERISTICS: TA = – 40°C to +85°C, VIN = +5V, C1 = C2 = 10µF (TCM828), C1 = C2 = 3.3µF (TCM829) unless otherwise noted. Typical values are at TA = +25°C. (Note 2) Symbol Parameter Device IDD Supply Current TCM828 TCM829 V+ FOSC Supply Voltage Range Oscillator Frequency ROUT Output Resistance Test Conditions RLOAD = 10kΩ TCM828 TCM829 IOUT = 5mA Min Typ Max Unit — — 1.5 6 19 — — — — — — — 115 325 5.5 20 54.3 65 µA V kHz Ω NOTE: 2. All – 40°C to +85°C specifications above are guaranteed by design. PIN DESCRIPTION Pin No. (5-Pin SOT-23A) 1 2 3 4 5 TCM828/829-4 Symbol OUT VIN C1– GND + C1 5/22/00 Description Inverting charge pump output. Positive power supply input. Commutation capacitor negative terminal. Ground. Commutation capacitor positive terminal. 2 © 2001 Microchip Technology Inc. DS21488A Switched Capacitor Voltage Converters TCM828 TCM829 (4) Losses that occur during charge transfer (from the commutation capacitor to the output capacitor) when a voltage difference between the two capacitors exists. DETAILED DESCRIPTION The TCM828/829 charge pump converters invert the voltage applied to the VIN pin. Conversion consists of a twophase operation (Figure 1). During the first phase, switches S2 and S4 are open and S1 and S3 are closed. During this time, C1 charges to the voltage on VIN and load current is supplied from C2. During the second phase, S2 and S4 are closed, and S1 and S3 are open. This action connects C1 across C2, restoring charge to C2. Most of the conversion losses are due to factors (2), (3) and (4) above. These losses are given by Equation 1. PLOSS (2, 3, 4) = IOUT2 x ROUT ≅ IOUT2 x [(f 1 +8RSWITCH + 4ESRC1 + ESRC2 OSC) C1 ] S2 S1 IN Equation 1. The 1/(fOSC)(C1) term in Equation 1 is the effective output resistance of an ideal switched capacitor circuit (Figures 2a, 2b). The losses in the circuit due to factor (4) above are also shown in Equation 2. The output voltage ripple is given by Equation 3. TCM828/829 C1 C2 S3 S4 VOUT = – (VIN) [ PLOSS (4) = (0.5)(C1)(VIN2– VOUT2) + (0.5)(C2)(VRIPPLE2 – 2VOUTVRIPPLE) Figure 1. Ideal Switched Capacitor Charge Pump ] xf OSC Equation 2. APPLICATIONS INFORMATION Output Voltage Considerations VRIPPLE = The TCM828/829 perform voltage conversion but do not provide regulation. The output voltage will droop in a linear manner with respect to load current. The value of this equivalent output resistance is approximately 25Ω nominal at +25°C and VIN = +5V. VOUT is approximately – 5V at light loads, and droops according to the equation below: IOUT +2(IOUT)(ESRC2) (fOSC)(C2) Equation 3. f V+ VOUT C2 C1 VDROOP = IOUT x ROUT VOUT = – (VIN – VDROOP) Charge Pump Efficiency RL Figure 2a. Ideal Switched Capacitor Model The overall power efficiency of the charge pump is affected by four factors: REQUIV V+ REQUIV = (1) Losses from power consumed by the internal oscillator, switch drive, etc. (which vary with input voltage, temperature and oscillator frequency). (2) I2R losses due to the on-resistance of the MOSFET switches on-board the charge pump. (3) Charge pump capacitor losses due to effective series resistance (ESR). VOUT 1 f x C1 C2 RL Figure 2b. Equivalent Output Resistance © 2001 Microchip Technology Inc. DS21488A 3 TCM828/829-4 5/22/00 Switched Capacitor Voltage Converters TCM828 TCM829 Capacitor Selection VIN C3 3.3µF* In order to maintain the lowest output resistance and output ripple voltage, it is recommended that low ESR capacitors be used. Additionally, larger values of C1 will lower the output resistance and larger values of C2 will reduce output ripple. (See Equation 1(b)). Table 1 shows various values of C1 and the corresponding output resistance values @ +25°C. It assumes a 0.1Ω ESRC1 and 2Ω RSW. Table 2 shows the output voltage ripple for various values of C2. The VRIPPLE values assume 10mA output load current and 0.1Ω ESRC2. VOUT 1 C1+ OUT 2 IN TCM828 TCM829 3 C1– 5 C2 3.3µF* C1 3.3µF* GND RL 4 *10µF (TCM828) Table 1. Output Resistance vs. C1 (ESR = 0.1Ω) Voltage Inverter C1(µF) TCM828 ROUT (Ω) TCM829 ROUT (Ω) 0.1 1 3.3 10 47 100 850 100 42 25 18 17 302 45 25 19 17 17 Figure 3. Test Circuit Cascading Devices Two or more TCM828/829’s can be cascaded to increase output voltage (Figure 4). If the output is lightly loaded, it will be close to (– 2 x VIN) but will droop at least by ROUT of the first device multiplied by the IQ of the second. It can be seen that the output resistance rises rapidly for multiple cascaded devices. For large negative voltage requirements see the TC682 or TCM680 data sheets. Table 2. Output Voltage Ripple vs. C2 (ESR = 0.1Ω) IOUT 10mA C2(µF) TCM828 VRIPPLE (mV) TCM829 VRIPPLE (mV) 1 3.3 10 47 100 835 254 85 20 10 286 88 31 8 5 ... + VIN 2 2 3 3 Input Supply Bypassing C1 The VIN input should be capacitively bypassed to reduce AC impedance and minimize noise effects due to the switching internal to the device. The recommended capacitor depends on the configuration of the TCM828/829. If the device is loaded from OUT to GND it is recommended that a large value capacitor (at least equal to C1) be connected from the input to GND. If the device is loaded from IN to OUT a small (0.1µF) capacitor from IN to OUT is sufficient. 5 4 C1 5 1 TCM828 TCM829 "n" 1 VOUT C2 C2 VOUT = –nVIN Figure 4. Cascading TCM828s or TCM829s to Increase Output Voltage Paralleling Devices To reduce the value of ROUT, multiple TCM828/829s can be connected in parallel (Figure 5). The output resistance will be reduced by a factor of N where N is the number of TCM828/829’s. Each device will require it’s own pump capacitor (C1), but all devices may share one reservoir capacitor (C2). However, to preserve ripple performance the value of C2 should be scaled according to the number of paralleled TCM828/829’s. The most common application for charge pump devices is the inverter (Figure 3). This application uses two external capacitors – C1 and C2 (plus a power supply bypass capacitor, if necessary). The output is equal to V– IN plus any voltage drops due to loading. Refer to Table 1 and Table 2 for capacitor selection. 5/22/00 TCM828 TCM829 "1" ... Voltage Inverter TCM828/829-4 4 4 © 2001 Microchip Technology Inc. DS21488A Switched Capacitor Voltage Converters TCM828 TCM829 Diode Protection for Heavy Loads ROUT = ROUT OF SINGLE DEVICE NUMBER OF DEVICES + VIN 2 2 3 3 C1 4 5 When heavy loads require the OUT pin to sink large currents being delivered by a positive source, diode protection may be needed. The OUT pin should not be allowed to be pulled above ground. This is accomplished by connecting a Schottky diode (1N5817) as shown in Figure 7. ... TCM828 TCM829 "1" 4 C1 5 1 TCM828 TCM829 "n" ... 1 VOUT GND 4 ... – VOUT = VIN C2 TCM828 TCM829 Figure 5. Paralleling TCM828s or TCM829s to Reduce Output Resistance OUT Voltage Doubler/Inverter Another common application of the TCM828/829 is shown in Figure 6. This circuit performs two functions in combination. C1 and C2 form the standard inverter circuit described above. C3 and C4 plus the two diodes form the voltage doubler circuit. C1 and C3 are the pump capacitors and C2 and C4 are the reservoir capacitors. Because both sub-circuits rely on the same switches if either output is loaded, both will droop toward GND. Make sure that the total current drawn from both the outputs does not total more than 40mA. 1 Figure 7. High V– Load Current Layout Considerations As with any switching power supply circuit good layout practice is recommended. Mount components as close together as possible to minimize stray inductance and capacitance. Also use a large ground plane to minimize noise leakage into other circuitry. + VIN 2 3 D1, D2 = 1N4148 C1 4 TCM828 TCM829 5 D1 1 – VOUT = VIN C2 D2 VOUT = (2VIN) – (VFD1) – (VFD2) C3 C4 Figure 6. Combined Doubler and Inverter © 2001 Microchip Technology Inc. DS21488A 5 TCM828/829-4 5/22/00 Switched Capacitor Voltage Converters TCM828 TCM829 TYPICAL CHARACTERISTICS Circuit of Figure 3, VIN = +5V, C1 = C2 = C3, TA = +25°C, unless otherwise noted. Output Resistance vs. Temperature 40 60 70 35 50 40 TCM829 20 10 1.5 2.5 40 VIN = 3.3V 30 20 VIN = 5.0V 10 OUTPUT CURRENT (mA) 30 VIN = 3.15V, V– = – 2.5V 20 15 VIN = 1.9V, VOUT = – 1.5V 10 5 0 0 5 10 15 20 25 30 400 300 VIN = 3.15V, VOUT = – 2.5V 250 200 VIN = 1.9V, VOUT = – 1.5V 150 100 50 0 0 35 120 PUMP FREQUENCY (kHz) 100 80 TCM829 TCM828 20 0 2.5 3 3.5 4 4.5 SUPPLY VOLTAGE (V) TCM828/829-4 5 10 25 20 25 30 5/22/00 10 0 5 5.5 30 20 40 TCM829 Output Voltage Ripple vs. Capacitance 300 VIN = 4.75V, VOUT = – 4.0V 250 200 VIN = 3.15V, VOUT = – 2.5V 150 VIN = 1.9V, VOUT = – 1.5V 100 50 0 0 35 5 10 15 20 30 35 CAPACITANCE (µF) TCM828 Pump Frequency vs. Temperature TCM829 Pump Frequency vs. Temperature 45 VIN = 5.0V 10 8 VIN = 3.3V VIN = 1.5V 6 4 0 –40 VIN = 5.0V 40 12 2 2 VIN = 1.9V, VOUT = –1.5V 10 CAPACITANCE (µF) 14 1.5 15 CAPACITANCE (µF) VIN = 4.75V, VOUT = – 4.0V 350 Supply Current vs. Supply Voltage 40 20 85°C 450 CAPACITANCE (µF) 60 25°C TCM828 Output Voltage Ripple vs. Capacitance OUTPUT VOLTAGE RIPPLE (mVp-p) VIN = 4.75V, V– = – 4.0V 25 VIN = 3.15V, VOUT = – 2.5V 25 TEMPERATURE (°C) TCM829 Output Current vs. Capacitance 35 30 0 0°C SUPPLY VOLTAGE (V) 40 VIN = 4.75V, VOUT = – 4.0V 5 0 –40°C 4.5 3.5 50 OUTPUT VOLTAGE RIPPLE (mVp-p) TCM828 VIN = 1.5V 60 PUMP FREQUENCY (kHz) 30 OUTPUT CURRENT (mA) 80 0 SUPPLY CURRENT (µA) TCM828 Output Current vs. Capacitance 70 OUTPUT RESISTANCE (Ω) OUTPUT RESISTANCE (Ω) Output Resistance vs. Supply Voltage 35 30 VIN = 3.3V 25 VIN = 1.5V 20 15 10 5 0°C 25°C TEMPERATURE (°C) 6 85°C 0 –40°C 0°C 25°C 85°C TEMPERATURE (°C) © 2001 Microchip Technology Inc. DS21488A Switched Capacitor Voltage Converters TCM828 TCM829 TYPICAL CHARACTERISTICS (Cont.) Circuit of Figure 3, VIN = +5V, C1 = C2 = C3, TA = +25°C, unless otherwise noted. Output Voltage vs. Output Current Efficiency vs. Output Current 100 VIN = 5.0V –1 VIN = 2.0V EFFICIENCY (%) OUTPUT VOLTAGE (V) 0 –2 VIN = 3.3V –3 –4 80 VIN = 3.3V VIN =1.5V 60 VIN = 5.0V –5 –6 40 0 10 20 30 40 OUTPUT CURRENT (mA) 50 0 10 20 30 40 OUTPUT CURRENT (mA) 50 MARKING Part Numbers and Part Marking 5-PIN SOT-23A & = part number code + temperature range (two-digit code). TCM828/829 TCM828ECT TCM829ECT Code CA CB C A ex: TCM828ECT = represents year and quarter code represents lot ID number © 2001 Microchip Technology Inc. DS21488A 7 TCM828/829-4 5/22/00 Switched Capacitor Voltage Converters TCM828 TCM829 TAPING FORM Component Taping Orientation for 5-Pin SOT-23A (EIAJ SC-74A) Devices PIN 1 User Direction of Feed User Direction of Feed Device Marking Device Marking W PIN 1 P Standard Reel Component Orientation TR Suffix Device (Mark Right Side Up) Reverse Reel Component Orientation RT Suffix Device (Mark Upside Down) Carrier Tape, Number of Components Per Reel and Reel Size Package 5-Pin SOT-23A Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size 8 mm 4 mm 3000 7 in PACKAGE DIMENSIONS 5-Pin SOT-23A (EIAJ SC-74A) .075 (1.90) REF. .071 (1.80) .059 (1.50) .122 (3.10) .098 (2.50) .020 (0.50) .012 (0.30) PIN 1 .037 (0.95) REF. .122 (3.10) .106 (2.70) .057 (1.45) .035 (0.90) .006 (0.15) .000 (0.00) TCM828/829-4 5/22/00 .010 (0.25) .004 (0.09) 10° MAX. .024 (0.60) .004 (0.10) 8 Dimensions: inches (mm) © 2001 Microchip Technology Inc. DS21488A Switched Capacitor Voltage Converters TCM828 TCM829 WORLDWIDE SALES AND SERVICE AMERICAS New York Corporate Office 150 Motor Parkway, Suite 202 Hauppauge, NY 11788 Tel: 631-273-5305 Fax: 631-273-5335 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: 480-792-7627 Web Address: http://www.microchip.com Rocky Mountain 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7966 Fax: 480-792-7456 ASIA/PACIFIC (continued) San Jose Microchip Technology Inc. 2107 North First Street, Suite 590 San Jose, CA 95131 Tel: 408-436-7950 Fax: 408-436-7955 Singapore Microchip Technology Singapore Pte Ltd. 200 Middle Road #07-02 Prime Centre Singapore, 188980 Tel: 65-334-8870 Fax: 65-334-8850 Taiwan Atlanta 6285 Northam Drive, Suite 108 Mississauga, Ontario L4V 1X5, Canada Tel: 905-673-0699 Fax: 905-673-6509 500 Sugar Mill Road, Suite 200B Atlanta, GA 30350 Tel: 770-640-0034 Fax: 770-640-0307 Microchip Technology Taiwan 11F-3, No. 207 Tung Hua North Road Taipei, 105, Taiwan Tel: 886-2-2717-7175 Fax: 886-2-2545-0139 ASIA/PACIFIC Austin EUROPE China - Beijing Australia Analog Product Sales 8303 MoPac Expressway North Suite A-201 Austin, TX 78759 Tel: 512-345-2030 Fax: 512-345-6085 Boston 2 Lan Drive, Suite 120 Westford, MA 01886 Tel: 978-692-3848 Fax: 978-692-3821 Boston Analog Product Sales Unit A-8-1 Millbrook Tarry Condominium 97 Lowell Road Concord, MA 01742 Tel: 978-371-6400 Fax: 978-371-0050 Toronto Microchip Technology Beijing Office Unit 915 New China Hong Kong Manhattan Bldg. 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