AIC1845 Regulated 5V Charge Pump In SOT-23 DESCRIPTION FEATURES Ultralow Power: IIN = 13µA Regulated 5V ±4% Output Voltage The AIC1845 is a micropower charge pump Output Current: 100mA (VIN =3.3V) output. The input voltage range is 2.7V to 5.0V. 110mA (VIN =3.6V) Input Range: 2.7V to 5.0V No Inductors Needed Extremely low operating current (13µA typical Very Low Shutdown Current: <1µA Internal Oscillator: 650KHz Short-Circuit and Overtemperature Protection 6-Pin SOT-23 Package capacitors at VIN and VOUT ) make the AIC1845 DC/DC converter that produces a regulated 5V with no load) and a low external-part count (one 0.22µF flying capacitor and two small bypass ideally suitable for small, battery-powered applications. The AIC1845 operates as a PSM (Pulse Skipping Modulation) mode switched capacitor voltage doubler to produce a regulated output APPLICATIONS and features with thermal shutdown capability White or Blue LED Backlighting SIM Interface Supplies for Cellular Telephones Li-Ion Battery Backup Supplies Local 3V to 5V Conversion Smart Card Readers PCMCIA Local 5V Supplies and short circuit protection. The AIC1845 is available in a 6-pin SOT-23 package. TYPICAL APPLICATION CIRCUIT VOUT ** R1 U1 1-Cell 1 VOUT CIN 2.2µF Li-ion Battery 2 3 GND SHDN C+ 6 VIN C- * COUT 2.2µF * * * 5 4 0.22µF CFLY AIC1845 Regulated 5V Output from 2.7V to 5.0V Input * WLED series number: NSPW310BS, VF=3.6V, IF=20mA ** R1 = VOUT − VF , NWLED: The number of WLED IF × N WLED CIN, COUT: CELMK212BJ225MG (X5R) (0805), TAIYO YUDEN CFLY Analog Integrations Corporation : CEEMK212BJ224KG (X7R) (0805), TAIYO YUDEN Si-Soft Research Center DS-1845P-03 010405 3A1, No.1, Li-Hsin Rd. I, Science Park, Hsinchu 300, Taiwan, R.O.C. TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw 1 AIC1845 ORDERING INFORMATION AIC1845XXXX PIN CONFIGURATION PACKING TYPE TR: TAPE & REEL BG: BAG SOT-23-6 TOP VIEW PACKAGE TYPE G: SOT-23-6 C+ VIN 6 5 C4 (MARK SIDE) 1 2 3 VOUT GND SHDN C: COMMERCIAL P: LEAD FREE COMMERCIAL Example: AIC1845CGTR in SOT-23-6 Package & Taping & Reel Packing Type AIC1845PGTR in Lead Free SOT-23-6 Package & Taping & Reel Packing Type SOT-23-6 Marking Part No. Marking AIC1845CG BO50 AIC1845PG BO50P ABSOLUATE MAXIMUM RATINGS VIN to GND 6V VOUT to GND 6V All Other Pins to GND 6V VOUT Short-Circuit Duration Operating Temperature Range Junction Temperature Storage Temperature Range Lead Temperature (Sordering 10 Sec.) Continuous -40°C to 85 °C 125°C -65°C to 150 °C 260°C Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. TEST CIRCUIT Refer to TYPICAL APPLICATION CIRCUIT. 2 AIC1845 ELECTRICAL CHARACTERISTICS (TA=25°C, CFLY=0.22µF, CIN=2.2µF, COUT=2.2µF, unless otherwise specified.) (Note 1) PARAMETER TEST CONDITIONS Input Voltage Output Voltage Continuous Output Current Supply Current 2.7V≤ VIN< 3.3V, IOUT≤ 30mA 3.3V≤ VIN≤ 5.0V, IOUT≤ 60mA VIN=3V, VOUT=5.0V SHDN =VIN 2.7V≤ VIN≤ 5.0V, IOUT=0 , SHDN =VIN 2.7V≤ VIN≤ 5.0V, SYMBOL MIN. VIN 2.7 4.8 TYP. 5.0 MAX. UNIT 5.0 V 5.2 VOUT V 4.8 IOUT 5.0 5.2 60 mA ICC 13 30 µA I SHDN 0.01 1.0 µA VR 60 mV Shutdown Current IOUT=0 , SHDN =0V Output Ripple VIN =3V , IOUT=50mA Efficiency VIN =2.7V , IOUT=30mA η 83 % Switching Frequency Oscillator Free Running fOSC 650 KHz Shutdown Input Threshold (High) Shutdown Input Threshold (Low) Shutdown Input Current (High) Shutdown Input Current (Low) VIH 1.4 V VIL 0.3 V SHDN =VIN IIH -1 1 µA SHDN = 0V IIL -1 1 µA Vout Turn On Time VIN =3V, IOUT = 0mA tON 0.5 mS Output Short Circuit Current VIN=3V, VOUT= 0V, SHDN = VIN ISC 170 mA Note1: Specifications are production tested at TA=25°C. Specifications over the -40°C to 85°C operating temperature range are assured by design, characterization and correlation with Statistical Quality Controls (SQC). 3 AIC1845 TYPICAL PERFORMANCE CHARACTERISTICS (CIN, COUT: CELMK212BJ225MG, CFLY: CEEMK212BJ224KG) 5.15 20 IOUT=25mA COUT=10µF CFLY=1µF 5.05 Supply Current (µΑ) Output Voltage (V) 5.10 TA = -40°C 5.00 4.95 TA =25°C 4.90 TA=-40°C 15 10 IOUT=0µA CFLY=1µF VSHDN=VIN TA =85°C 4.85 2.5 3.0 3.5 4.0 4.5 5 5.0 2.5 3.0 3.5 Supply Voltage (V) Output Voltage (V) Output Voltage (V) 5.1 5.05 VIN=3.6V 5.00 4.95 5.0 4.9 4.8 VIN=3.3V VIN=3.6V 4.7 TA=25°C CFLY=0.22µF COUT=2.2µF VIN=3.3V 4.90 VIN=2.7V 4.85 0 20 4.6 VIN=3.0V 40 60 80 100 120 140 4.5 160 0 10 20 30 VIN=2.7V 40 50 60 70 VIN=3.0V 80 90 100 110 120 130 Output Current (mA) Output Current (mA) Fig. 4 Load Regulation Fig. 3 Load Regulation 100 100 VIN=2.7V 90 60 VIN=3.0V 50 VIN=3.3V 40 VIN=3.6V Efficiency (%) CT=25°C CFLY=1µF 70 VIN=2.7V VIN=3.0V 80 70 60 20 TA=25°C CFLY=0.22µF 40 10 0.001 VIN=3.6V VIN=3.3V 50 30 0 5.0 5.2 TA=25°C COUT=10µF CFLY=1µF 5.10 Efficiency (%) 4.5 Fig. 2 No Load Supply Current vs. Supply Voltage 5.15 80 4.0 Supply Voltage (V) Fig. 1 Line Regulation 90 TA=85°C TA=25°C 0.01 0.1 1 Output Current (mA) Fig. 5 Efficiency 10 100 30 0.01 0.1 1 10 100 Output Current (mA) Fig. 6 Efficiency 4 AIC1845 TYPICAL PERFORMANCE CHARACTERISTICS 50 (Continued) 175 45 150 35 Output Ripple (mV) Output Ripple (mV) 40 VIN=3.6V 30 25 VIN=3.3V 20 15 VIN=3.0V 10 0 COUT=10µF VIN=2.7V 5 0 20 40 60 100 120 VIN=3.6V 100 75 VIN=3.3V 50 VIN=2.7V CFLY=0.22µF 0 140 0 20 40 Fig.7 Output Current vs. Output Ripple 60 80 100 120 Output Current (mA) Output Current (mA) 140 Fig. 8 Output Current vs. Output Ripple 1000 5.05 VIN=2.5V Output Voltage (V) 900 Frequency (KHz) COUT=2.2µF VIN=3.0V 25 CFLY=1µF 80 125 800 700 600 5.00 VIN=3.0V CFLY=1µF IOUT=50mA 4.95 4.90 500 400 -60 -40 -20 0 20 40 60 80 100 120 4.85 -60 140 Temperature (°C) Fig. 9 Frequency vs. Temperature -40 -20 Fig. 10 0 20 40 60 80 100 120 140 Temperature (°C) Output Voltage vs. Temperature 220 TA=25°C CFLY=1µF 260 240 Short-Circuit Current (mA) Short-Circuit Current (mA) 280 220 200 180 160 140 120 100 200 180 160 140 120 TA=25°C CFLY=0.22µF 100 2.5 3.0 3.5 4.0 4.5 5.0 Supply Voltage (V) Fig. 11 Short-Circuit Current vs. Supply Voltage 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Supply Voltage (V) Fig. 12 Short-Circuit Current vs. Supply Voltage 5 AIC1845 TYPICAL PERFORMANCE CHARACTERISTICS (Continued) CN CN VOUT VOUT Fig. 13 Output Ripple VIN=3.0V, IOUT=50mA, COUT=10µF,CFLY=1µF VOUT IOUT VOUT Fig. 15 Load Transient Response VIN=3.0V, IOUT=0mA~50mA,COUT=10µF, CFLY=1µF VOUT V SHDN Fig. 17 Start-Up Time VIN=3.0V, IOUT=0A, COUT=10µF Fig. 14 Output Ripple VIN=3.0V, IOUT=50mA, COUT=2.2µF, CFLY=0.22µF IOUT Fig. 16 Load Transient Response VIN=3.0V, IOUT=0mA~50mA,COUT=2.2µF, CFY=0.22µF VOUT V SHDN Fig. 18 Start-Up Time VIN=3.0V, IOUT=0A, COUT=2.2µF 6 AIC1845 BLOCK DIAGRAM VOUT 2 COUT 2.2µF C+ 1 VIN CFLY 2 Control 0.22µF CIN 2.2µF COMP CVREF SHDN 1 PIN DESCRIPTIONS PIN 1:VOUT - PIN 2: GND - Regulated output voltage. For the best performance, VOUT should be bypassed with a 2.2µF (min) low ESR capacitor with the shortest distance in between. Ground. Should be tied to a ground plane for best performance. PIN 3: SHDN - Active low shutdown input. A low voltage on SHDN disables the AIC1845. SHDN is not allowed to float. PIN 4: C- - Flying capacitor negative terminal. PIN 5: VIN - Input supply voltage. VIN should be bypassed with a 2.2µF (min) low ESR capacitor. PIN 6: C+ - Flying capacitor positive terminal. 7 AIC1845 APPLICATION INFORMATION Introduction Short Circuit/Thermal Protection AIC1845 is a micropower charge pump DC/DC AIC1845 owns a built-in short circuit current converter that produces a regulated 5V output limiting as well as an over temperature protection. with an input voltage range from 2.7V to 5.0V. It During the short circuit condition, the output utilizes the charge pump topology to boost VIN to current a regulated output voltage. Regulation is obtained approximately 170mA. This short circuit current by sensing the output voltage through an internal will cause a rise in the internal IC junction resistor divider. A switched doubling circuit temperature. When the die temperature exceeds enables the charge pump when the feedback 150°C, the thermal protection will shut the charge voltage is lower than the trip point of the internal pump switching operation down and the die comparator, and vice versa. When the charge temperature will reduce afterwards. Once the die pump is enabled, a two-phase non-overlapping temperature drops below 135°C, the charge pump clock activates the charge pump switches. To switching circuit will re-start. If the fault doesn’t maximize battery life for a battery-used application, eliminate, the above protecting operation will quiescent current is limited up to 13µA. repeat again and again. It allows AIC1845 to is automatically constrained at continuously work at short circuit condition without Operation damaging the device. This kind of converter uses capacitors to store and transfer energy. Since the capacitors can’t change their voltage level abruptly, the voltage Shutdown ratio of VOUT over VIN is limited to some range. In shutdown mode, the output is disconnected Capacitive voltage conversion is obtained by from input. The input current gets extremely low switching a capacitor periodically. It first charges since most of the circuitry is turned off. Due to the capacitor by connecting it across a voltage high impedance, shutdown pin can’t be floated. source and then connects it to the output. Referring to Fig. 19, during the on state of internal clock, Q1 and Q4 are closed, which charges C1 to Efficiency VIN level. During the off state, Q3 and Q2 are Referring to Fig. 20 and Fig. 21 here shows the closed. The output voltage is VIN plus VC1, that is, circuit of charge pump at different states of 2VIN. operation. RDS-ON is the resistance of the switching VIN Q2 VOUT Q1 CIN COUT C1 Q3 Q4 Fig. 19 The circuit of charge pump element at conduction. ESR is the equivalent series resistance of the flying capacitor C1. IONAVE and IOFF-AVE are the average current during on state and off state, respectively. D is the duty cycle, which means the proportion the on state takes. Let’s take advantage of conversation of charge for capacitor C1. Assume that the capacitor C1 has reached its steady state. The amount of charge flowing into C1 during on state is equal to that flowing out of C1 at off state. 8 AIC1845 ION− AVE × DT = IOFF − AVE × (1 − D)T (1) External Capacitor Selection ION- AVE × D = IOFF - AVE × (1 − D) (2) Three external capacitors, CIN, COUT and CFLY, determine AIC1845 performances, in the aspects IIN = ION- AVE × D + IOFF- AVE × (1 − D) = 2 × ION- AVE × D (3) = 2 × IOFF- AVE × (1 - D) of output ripple voltage, charge pump strength and transient. Optimum performance can be obtained by the use of ceramic capacitors with low ESR. Due to high ESR, capacitors of tantalum IOUT = IOFF- AVE × (1 − D) and aluminum are not recommended for charge IIN = 2IOUT pump application. For AIC1845, the controller takes the PSM (Pulse Skipping Modulation) control strategy. When the To reduce noise and ripple, a low ESR ceramic duty cycle is limited to 0.5, there will be: capacitor, ranging from 2.2µF to 10µF, is ION- AVE × 0.5 × T = IOFF- AVE × (1 − 0.5) × T COUT determines the amount of output ripple ION- AVE = IOFF- AVE According to the equation (4), we know that as long as the flying capacitor C1 is at steady state, the input current is twice the output current. The efficiency of charge pump is given below: V V V ×I ×I η = OUT OUT = OUT OUT = OUT VIN × IIN VIN × 2IOUT 2VIN VIN ION Q2 Q1 RDS-ON CIN Q3 recommended for CIN and COUT. The value of COUT ESR C1 VOUT voltage. An output capacitor with larger value ..........(5) results in smaller ripple. CFLY is critical for the strength of charge pump. The larger CFLY is, the larger output current and smaller ripple voltage obtain. However, large CIN ......(6) and COUT are expected when a large .... CFLY applies. The ratio of CIN (as well as COUT) to CFLY should be approximately 10:1. The value of capacitors, which is used under operation conditioin, determines the performance Q4 of a charge pump converter. And two factors, as follows, affect the capacitance of capacitor. RDS-ON Fig. 20 The on state of charge pump circuit 1. Material: Ceramic capacitors of different materials, such as X7R, X5R, Z5U and Y5V, VIN CIN RDS-ON Q2 Q1 Q3 VOUT COUT ESR Q4 RDS-ON C1 IOFF have different tolerance in temperature and differnet cpacitance loss. For example, a X7R or X5R type of capacitor can retain most of the capacitance at temperature from -40°C to 85°C, but a Z5U or Y5V type will lose most of the capacitance at that temperature range. Fig. 21 The off state of charge pump circuit 9 AIC1845 2. Package Size: A ceramic capacitor with large volume (0805), gets a lower ESR than a small one (0603). Therefore, large devices switching element is 2 × PRDS −ON ≅ IOUT can improve more transient response than 2 × RDS - ON 0.5(1 − 0.5) 2 = IOUT × 8R DS − ON small ones. Table 1 lists the recommended components for AIC1845 application. 2 PESR ≅ IOUT × ESR × 2 = IOUT × 4ESR Table.1 Bill of Material Design- Part ator Type CIN 2.2µ CFLY 0.22µ COUT 2.2µ Description 1 0.5(1 − 0.5) Vendor Phone In fact, no matter the current is at on state or off state, it decays exponentially rather than flows CELMK212BJ- TAIYO 225MG (X5R) YUDEN CEEMK212BJ TAIYO -224KG (X7R) YUDEN CELMK212BJ- TAIYO 225MG (X5R) YUDEN (02) 27972155~9 steadily. And the root mean square value of exponential decay is not equal to that of steady (02) 27972155~9 flow. That is why the approximation comes from. Let’s treat the charge pump circuit in another (02) 27972155~9 approach and lay the focus on the flying capacitor C1. Referring to Fig. 20, when the circuit is at the Power Dissipation on state, the voltage across C1 is: Let’s consider the power dissipation of RDS-ON and ESR. Assume that the RDS-ON of each internal VC-ON (t) = VIN − 2R DS−ON × ION (t) - ESR × ION (t) …(9) switching element in AIC1845 is equal and ESR is the equivalent series resistance of CFLY (ref to Fig. 20 and Fig. 21). The approximation of the power loss of RDS-ON and ESR are given below: PRDS−ON 2 ≅ ION - AVE 2 × 2RDS − ON × D + IOFF - AVE × 2RDS − ON × (1 − D) IIN 2 I ) × 2RDS- ON × D + ( OUT )2 × 2RDS- ON × (1 - D) 2D 1- D 2IOUT 2 I =( ) × 2RDS -ON × D + ( OUT )2 × 2RDS -ON × (1 - D) 2D 1- D 2 2 2 2 = IOUT × ( RDS- ON ) + IOUT × ( RDS -ON ) D 1- D 2 2 = IOUT × × RDS -ON D(1 - D) =( 2 2 PESR ≅ ION − AVE × ESR × D + I OFF − AVE × ESR × (1 − D) I IIN 2 ) × ESR × D + ( OUT ) 2 × ESR × (1 − D) 2D 1− D 1 1 2 2 = IOUT × ESR × + IOUT × ESR × D 1- D 1 2 = IOUT × ESR × D(1 - D) When the duty cycle is 0.5, the power loss of =( The average of VC1 during the on state is: VC−ON− AVE = VIN − 2R DS−ON × ION− AVE − ESR × ION− AVE ……………………….(10) Similarly, referring to Fig. 21, when the circuit is at the off state, the voltage of C1 is: VC-OFF (t) = VOUT − VIN + 2R DS-ON × IOFF (t) + ESR × IOFF (t) ……………………………(11) The average of VC1 during the off state is: VC−OFF− AVE = VOUT − VIN + 2R DS−ON × IOFF− AVE .......... + ESR(7) × IOFF− AVE ………………..(12) The difference of charge stored in C1 between on state and off state is the net charge transferred to the output in one cycle. 10 AIC1845 ∆Q = Q ON - Q OFF = C1 × (VC1−ON− AVE − VC1−OFF − AVE ) = C1 × (2VIN - VOUT - 2R DS-ON × ION- AVE - 2R DS-ON × IOFF- AVE - ESR × ION− AVE - ESR × IOFF- AVE ) ………(13) I I I IOUT − 2R DS −ON × OUT - ESR × OUT - ESR × OUT ) 1- D D 1− D D 1 + ESR) × IOUT × ] D(1 − D) = C1 × (2VIN − VOUT − 2R DS −ON × = C1 × [2VIN − VOUT − (2R DS−ON Thus the output current can be written as IOUT = f × ∆Q = f × (Q ON − Q OFF ) = f × C1 × [2VIN − VOUT - (2R DS-ON + ESR ) × IOUT × (14) 1 ] D(1 - D) When the duty cycle is 0.5, the output current can be written as: IOUT = f × C1 × [2VIN − VOUT − (2R DS−ON + ESR) × IOUT × 1 ] 0.5(1 − 0.5) (15) = fC1 × [2VIN − VOUT − (8R DS−ON + 4ESR) × IOUT ] And equation (15) can be re-written as: 2VIN − VOUT = 1 × IOUT + (8R DS−ON + 4ESR) × IOUT fC1 According the equation (16), when the duty cycle is 0.5, the equivalent circuit of charge pump is shown in Fig. 22. The term 8RDS-ON is the total effect of switching resistance, 1/fC1 is the effect (16) IOUT 2VIN 1/fC1 8RDS-ON VOUT 4ESR LOAD COUT of flying capacitor and 4ESR is its equivalent resistance. Fig. 22 The euqivalent circuit of charge pump From the equivalent circuit shown in Fig. 22, it is Layout Considerations seen that the terms 1/fC1, 4ESR and 8RDS-ON should be as small as possible to get large output Due to the switching frequency and high transient current. However, for users, since the RDS-ON is current of AIC1845, careful consideration of PCB fixed and manufactured in IC, what we can do is layout is necessary. To achieve the best to lower 1/fC1 and ESR. However even the effect performance of AIC1845, minimize the distance of 1/fC1 and ESR can be kept as small as between every possible, the term 8RDS-ON still dominates the minimize every role that limits the maximum output current. maximum trace width. Make sure each device two components connection length and also with a connects to immediate ground plane. Fig. 23 to Fig. 25 show the recommended layout. 11 AIC1845 Fig. 23 Top layer Fig. 24 Bottom layer Fig. 25 Topover layer APPLICATION EXAMPLES VIN CIN 2.2µ 1 2 3 VOUT GND VIN SHDN U1 2 GND CAP+ VIN 3 SHDN U2 CAP- 6 CFLY1 5 VOUT COUT 2.2µF 0.22µF 4 AIC1845 1 VOUT VSHDN CAP+ CAP- 6 CFLY2 0.22µF 5 4 AIC1845 CIN, COUT : TAIYO YUDEN Ceramic Capacitor, CELMK212BJ225MG (X5R) (0805) CFLY1, CFLY2: TAIYO YUDEN Ceramic Capacitor, CEEMK212BJ224KG (X7R) (0805) Fig. 26 Parallel Two AIC1845 to Obtain the Regulated 5V Output with large output current. USB CIN 2.2µF VOUT 1 2 3 VSHDN VOUT GND SHDN U1 CAP+ VIN CAP- 6 5 4 COUT 2.2µF CFLY 0.22µF AIC1845 CIN, COUT: TAIYO YUDEN Ceramic Capacitor, CELMK212BJ225MG (X5R) (0805) : TAIYO YUDEN Ceramic Capacitor, CEEMK212BJ224KG (X7R) (0805) CFLY1 Fig. 27 Regulated 5V from USB 12 AIC1845 PHYSICAL DIMENSIONS (unit: mm) SOT-23-6 D A A e e1 SEE VIEW B b WITH PLATING c A A2 SOT-26 MILLIMETERS MIN. MAX. A 0.95 1.45 A1 0.05 0.15 A2 0.90 1.30 b 0.30 0.50 c 0.08 0.22 D 2.80 3.00 E 2.60 3.00 E1 1.50 1.70 E E1 S Y M B O L 0.95 BSC 1.90 BSC L 0.30 L1 θ 0.60 0.60 REF 0° 8° 0.25 A1 BASE METAL SECTION A-A e e1 GAUGE PLANE SEATING PLANE θ L L1 VIEW B Note: Information provided by AIC is believed to be accurate and reliable. However, we cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AIC product; nor for any infringement of patents or other rights of third parties that may result from its use. We reserve the right to change the circuitry and specifications without notice. Life Support Policy: AIC does not authorize any AIC product for use in life support devices and/or systems. Life support devices or systems are devices or systems which, (I) are intended for surgical implant into the body or (ii) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 13