SS6845G

SS6845G SSC | Alldatasheet

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Technical content

www.SiliconStandard.com 1 of 13 SS6845G 7/21/2005 Rev.3 .01 Input voltage range: 2.7V to 5.0V Regulated output voltage of 5V ±4% PRODUCT SUMMARY Regulated 5V Charge Pump Output current: 100mA (VIN = 3.3V) 110mA (VIN = 3.6V)

FEATURES

Ultralow power: IIN = 13µA No inductors needed Very low shutdown current: <1µA Internal oscillator: 650KHz Short-circuit and over-temperature protection

APPLICATIONS

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

DESCRIPTION

The SS6 845G is a micropower charge pump DC/DC converter that produces a regulated 5V output. The input voltage range is 2.7V to 5.0V. Extremely low operating current (13 µA typic al with no load) and a low external part count (one 0.22µF flying capacitor and two small bypass capacitors at the input and output) make the SS6845G ideally suitable for small, battery- powered applications. The SS6 845 G operates as a PSM -mode (Pulse Skipping Modulation) switched capacitor voltage doubler to produce a regulated output and features thermal shutdown capability and short circuit protection. TYPICAL APPLICATION CIRCUIT VOUT 1 GND 2 SHDN C- 4 VIN 5 C+ 6 SS6845G CIN CFLY COUT VOUT 2.2µF 0.22µF 2.2µF 1-Cell Li-ion Battery ** * * Regulated 5V Output from 2.7V to 5.0V Input * WLED series number: NSPW310BS, VF=3.6V, IF=20mA WLEDF FOUT NI VV1R × −= , where NWLED is the number of WLEDs. CIN, COUT: CELMK212BJ225MG (X5R) (0805), TAIYO YUDEN CFLY : CEEMK212BJ224KG (X7R) (0805), TAIYO YUDEN Pb-free; RoHS-compliant SOT-23-6 package

www.SiliconStandard.com 2 of 13 SS6845G 7/21/2005 Rev.3.01 ORDERING INFORMATION PIN CONFIGURATION C-C+ 321 (MARK S IDE) V INSOT-23-6 T OP VIEW Packing type: TR: Tape and reel Package type: GG: RoHS-compliant SOT-23-6 SS6845GG TR GNDV OUT SHDN SOT-23-6 Marking Part No. Marking SS6845GG BO50P ABSOLUTE MAXIMUM RATINGS VIN to GND 6V VOUT to GND 6V All other ins to GND 6V VOUT short-circuit duration Continuous Operating ambient temperature range -40°C to 85 °C Junction temperature 125°C Storage temperature range -65°C to 150 °C Lead temperature (minimum 10 seconds) 260°C Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. TEST CIRCUIT Refer to the TYPICAL APPLICATION CIRCUIT on page 1.

www.SiliconStandard.com 3 of 13 SS6845G 7/21/2005 Rev.3.01

ELECTRICAL CHARACTERISTICS

(TA=25°C, CFLY=0.22µF, CIN=2.2µF, COUT=2.2µF, unless otherwise specified.) (Note 1) PARAMETER TEST CONDITIONS SYMBOL MIN. TYP. MAX. UNIT Input voltage VIN 2.7 5.0 V 2.7V≤ VIN< 3.3V, IOUT≤ 30mA 4.8 5.0 5.2 Output voltage 3.3V≤ VIN≤ 5.0V, IOUT≤ 60mA VOUT 4.8 5.0 5.2 V Continuous output current VIN=3V, VOUT=5.0V SHDN =VIN IOUT 60 mA Supply current 2.7V≤ VIN≤ 5.0V, IOUT=0 , SHDN =VIN ICC 13 30 µA Shutdown current 2.7V≤ VIN≤ 5.0V, IOUT=0 , SHDN =0V ISHDN 0.01 1.0 µA Output ripple VIN =3V, IOUT=50mA VR 60 mV Efficiency VIN =2.7V , IOUT=30mA η 83 % Switching frequency Oscillator free-running fOSC 650 KHz Shutdown input threshold (High) VIH 1.4 V Shutdown input threshold (Low) VIL 0.3 V Shutdown input current (High) SHDN =VIN IIH -1 1 µA Shutdown input current (Low) 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 T A=25°C. Specifications over the -40°C to 85°C operating temperature range are assured by design, characte rization and correlation with Statistical Quality Controls (SQC).

www.SiliconStandard.com 4 of 13 SS6845G 7/21/2005 Rev.3.01 TYPICAL PERFORMANCE CHARACTERISTICS (CN, COUT: CELMK212BJ225MG, CFLY: CEEMK212BJ224KG) Fig. 1 Line Regulation Output Voltage (V) 4.85 4.90 4.95 5.00 5.05 5.10 5.15 IOUT=25mA COUT=10µF CFLY=1µF TA =85°C Supply Voltage (V) TA =25°C TA = -40°C Fig. 2 No Load Supply Current vs. Supply Voltage Supply Current (µΑ) Supply Voltage (V) IOUT=0µA CFLY=1µF VSHDN=VIN TA=85°C TA=25°C TA=-40°C 0 20 40 60 80 100 120 140 160 4.85 4.90 4.95 5.00 5.05 5.10 5.15 Fig. 3 Load Regulation Output Voltage (V) Output Current (mA) TA=25°C COUT=10µF CFLY=1µF VIN=2.7V VIN=3.0V VIN=3.3V VIN=3.6V Fig. 4 Load Regulation Output Voltage (V) Output Current (mA) 0 10 20 30 40 50 60 70 80 90 100 110 120 1304.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 VIN=3.0V VIN=2.7V VIN=3.6VVIN=3.3V TA=25°C CFLY=0.22µF COUT=2.2µF Fig. 5 Efficiency Efficiency (%) 0.001 0.01 0.1 1 10 100 100 Output Current (mA) VIN=3.3V VIN=3.0V VIN=3.6V CT=25°C CFLY=1µF VIN=2.7V Fig. 6 Efficiency Efficiency (%) Output Current (mA) 0.01 0.1 1 10 100 100 VIN=3.6VVIN=3.3V VIN=3.0V TA=25°C CFLY=0.22µF VIN=2.7V

www.SiliconStandard.com 5 of 13 SS6845G 7/21/2005 Rev.3.01 TYPICAL PERFORMANCE CHARACTERISTICS (Continued) Fig.7 Output Current vs. Output Ripple Output Ripple (mV) 0 20 40 60 80 100 120 140 Output Current (mA) CFLY=1µF VIN=3.3V VIN=3.0V VIN=2.7V COUT=10µF VIN=3.6V Fig. 8 Output Current vs. Output Ripple Output Ripple (mV) Output Current (mA) 0 20 40 60 80 100 120 140 100 125 150 175 VIN=3.3V VIN=3.0V VIN=2.7V CFLY=0.22µF VIN=3.6V COUT=2.2µF -60 -40 -20 0 20 40 60 80 100 120 140400 500 600 700 800 900 1000 Fig. 9 Frequency vs. Temperature Frequency (KHz) Temperature (°C) VIN=2.5V -60 -40 -20 0 20 40 60 80 100 120 140 4.85 4.90 4.95 5.00 5.05 Fig. 10 Output Voltage vs. Temperature Output Voltage (V) Temperature (°C) VIN=3.0V CFLY=1µF IOUT=50mA 120 140 160 180 200 220 240 260 280 Fig. 11 Short-Circuit Current vs. Supply Voltage Short-Circuit Current (mA) Supply Voltage (V) TA=25°C CFLY=1µF Fig. 12 Short-Circuit Current vs. Supply Voltage Short-Circuit Current (mA) Supply Voltage (V) 100 120 140 160 180 200 220 TA=25°C CFLY=0.22µF

www.SiliconStandard.com 6 of 13 SS6845G 7/21/2005 Rev.3.01 TYPICAL PERFORMANCE CHARACTERISTICS (Continued) Fig. 13 Output Ripple VIN=3.0V, IOUT=50mA, COUT=10µF,CFLY=1µF VOUT CN VOUT CN Fig. 14 Output Ripple VIN=3.0V, IOUT=50mA, COUT=2.2µF, CFLY=0.22µF Fig. 15 Load Transient Response VIN=3.0V, IOUT=0mA~50mA,COUT=10µF, CFLY=1µF IOUT VOUT IOUT VOUT Fig. 16 Load Transient Response VIN=3.0V, IOUT=0mA~50mA,COUT=2.2µF, CFY=0.22µF Fig. 17 Start-Up Time VIN=3.0V, IOUT=0A, COUT=10µF SHDNV VOUT SHDNV VOUT Fig. 18 Start-Up Time VIN=3.0V, IOUT=0A, COUT=2.2µF

www.SiliconStandard.com 7 of 13 SS6845G 7/21/2005 Rev.3.01 BLOCK DIAGRAM COMP VREF SHDN COUT 2.2µF VOUT Control CFLY CIN 2.2µF VIN 0.22µF PIN DESCRIPTIONS PIN 1:VOUT - Regulated out put voltage. For the best performance, VOUT should be bypassed with a 2.2 µF (min) low ESR capacitor with the shortest possible leads. PIN 2: GND - 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 SS6845G. SHDN is not allowed to float. PIN 4: C- - Flying capacitor negative terminal. PIN 5: VIN - Input supply voltage. V IN should be bypassed with a 2.2µ F (min) low ESR capacitor. PIN 6: C+ - Flying capacitor positive terminal.

www.SiliconStandard.com 8 of 13 SS6845G 7/21/2005 Rev.3.01

APPLICATION INFORMATION

Introduction Short Circuit/Thermal Protection The SS6845G is a micropower charge pump DC/DC converter that produces a regulated 5V output with an input voltage range from 2.7V to 5.0V. It utilizes the charge pump topology to boost V IN to a regulated output voltage. Regulation is obtained by sensing the output voltage through an internal resistor divider. A switched doubling circuit enables the charge pump when the feedback voltage is lower than the trip point of the internal comparator, and vice versa. When the charge pump is enabled, a two-phase non-overlapping clock activates the charge pump switches. To maximize battery life for a battery-use application, quiescent current is limited to no more than 13µA. The SS6845G includes built-in short circuit current limiting as well as over-temperature protection. During a short circuit condition, the output current is automatically constrained to approximately 170mA. This short circuit current will cause a rise in the internal IC junction temperature. When the die temperature exceeds 150°C, the thermal protection will shut down the charge pump switching operation and the die temperature will then reduce. Once the die temperature drops below 135°C, the charge pump switching circuit will restart. If the fault has not been eliminated, the this protection mechanism will repeat again and again, allowing the SS6845G to work continuously in a short circuit condition without damaging the device. Operation This kind of converter uses capacitors to store and transfer energy. Since the capacitors can’t change their voltage level abruptly, the voltage ratio of V OUT over V IN is limited to some range. Capacitive voltage conversion is obtained by switching a capacitor peri odically. It first charges the capacitor by connecting it across a voltage source and then connects it to the output. Referring to Fig. 19, during the on state of internal clock, Q 1 and Q4 are closed, which charges C 1 to VIN level. During the off state, Q 3 and Q 2 are closed. The output voltage is VIN plus VC1, that is, 2VIN. Shutdown In shutdown mode, the output is disconnected from the input. The input current is extremely low since most of the circuitry is turned off. Due to high impedance, the shutdown pin cannot float. Efficiency The diagrams, Fig. 20 and Fig. 21 show the operation of the charge pump in the on and off states. R DS-ON is the resistance of the switching element during conduction. ESR is the equivalent series resistance of the flying capacitor C 1. I ON-AVE and IOFF-AVE are the average current during the on-state and off-state, respectively. D is the duty-cycle, which means the ratio of the on-state time to the total cycle time. Let's look at capacitor C1 - assuming that capacitor C 1, has reached its steady state, then the amount of charge flowing into C1 during the on-state is equal to that flowing out of C1 during the off-state. VOUT VIN COUTCIN Fig. 19 The circuit of charge pump

www.SiliconStandard.com 9 of 13 SS6845G 7/21/2005 Rev.3.01 D)T (1I DTI AVE OFFAVE ON − ×= × −− (1) External Capacitor Selection D) (1I D I AVE - OFFAVE - ON − × = × (2) Three external capacitors, C IN, C OUT and C FLY, determine SS6845G performance, in the area of output ripple voltage, charge pump strength and transients. Optimum performance can be obtained by the use of ceramic capacitors with low ESR. Due to their high ESR, tantalum and aluminum capacitors are not recommended for charge-pump applications. D) - (1I 2 D I 2 D) (1I D I I AVE - OFF AVE - ON AVE - OFFAVE - ON IN × × = × × = − × + × = (3) ) D (1I I AVE - OFFOUT −× = OUTIN 2I I= For the SS6845G, the controller uses the PSM (Pulse Skipping Modulation) control strategy. When the duty cycle is limited to 0.5, then: T 0.5) 1 ( I T 0.5I AVE - OFFAVE - ON ×− × = × × To reduce noise and ripple, a low ESR ceramic capacitor, ranging from 2.2 µF to 10µ F, is recommended for C IN and C OUT. The value of COUT determines the amount of output ripple voltage. An output capacitor with a larger value results in smaller ripple. 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: IN OUT OUTIN OUTOUT IN IN OUTOUT V 2I V I V I V I Vη =× ×=× ..(6) CFLY is critical to the performance of a charge pump. The larger C FLY is, the larger the output current and the smaller the resulting ripple voltage. However, a large CFLY requires large CIN and COUT. The ratio of C IN (as well as C OUT) to C FLY should be approximately 10:1. VOUT VIN COUT CIN RDS-ON RDS-ON ION ESR The values of the capacitors used under operating conditions, determine the performance of the charge pump converter, and two factors, described below, affect the value of the capacitors. Fig. 20 The on-state of charge pump circuit 1. Material: Ceramic capacitors of different materials, such as X7R, X5R, Z5U and Y5V, have different tolerances to temperature and capacitance can vary significantly. For example, X7R or X5R types of capacitor retain their capacitance over temperatures from -40°C to 85°C, but a Z5U or Y5V type will change a lot over that temperature range. VOUTVIN COUTCIN RDS-ON RDS-ON IOFF ESR Fig. 21 The off-state of charge pump circuit

www.SiliconStandard.com 10 of 13 SS6845G 7/21/2005 Rev.3.01 2. Package Size: A ceramic capacitor with large volume (0805), gets a lower ESR than a small one (0603). Therefore, larger devices provide improved transient response over smaller ones. Table 1 lists the recommended components for use with the SS6845G. Table.1 Bill of Material Design- ator Part Type Description Vendor CIN 2.2µ CELMK212BJ- 225MG (X5R) TAIYO YUDEN CFLY 0.22µ CEEMK212BJ -224KG (X7R) TAIYO YUDEN COUT 2.2µ CELMK212BJ- 225MG (X5R) TAIYO YUDEN Power Dissipation Now, let’s look at the power dissipation in RDS-ON and ESR. Assume that the RDS-ON of each internal switching element in the SS6845G is equal and ESR is the equivalent series resistance of C FLY (refer to Fig. 20 and Fig. 21). The approximation of the power losses of RDS-ON and ESR are given below: RD) - D(1 ) RD - 1 2( I ) RD 2( I D) - (12R )D - 1 I( D2R )2D 2I( D) - (12R )D - 1 I( D2R )2D ) D (12RI D2RI P ON - DS OUT ON - DS OUTON - DS OUT ON - DS 2OUT ON - DS 2OUT ON - DS 2OUT ON - DS 2IN ON DS AVE - OFFON DS AVE - ONR ON DS × × = × +× = ×× + ××= ×× + ×× = AVE OFF C II 2R V V V −−− − − ××+ − D) - D(1 1ESR I D - 1 1ESR ID 1ESR I D) (1 ESR )D 1 I( D ESR )2D D) (1 ESRI D ESRI P OUT OUT OUT 2OUT2IN AVE OFF AVE ONESR × × = × × + × × = With a duty-cycle of 0.5, the power loss of RDS-ON is 8R I R0.5) 0.5(1 2I P ON DS OUT ON - DS OUTR ON DS −× = ×−× ≅ 4ESRI 0.5) 0.5(1 1ESR I P OUT OUTESR × = −× × ≅ In fact, whether the current is the on-state or the off-state, it decays exponentially rather than flows steadily, and as the root mean square value of exponential decay is not equal to that of steady flow, then we must use an approximation. Let’s use another approach to look at the charge pump circuit and focus on the flying capacitor C1. Referring to Fig. 20, when the circuit is in the on state, the voltage across C1 is: (t) I ESR - (t) I 2R V (t) VONON ON DSINON - C ××−= − …(9) The average of VC1 during the on-state is: AVE ONAVE ON ON DSINAVE ON C I ESRI2R VV −−−− − ×−×−= Similarly, referring to Fig. 21, when the circuit is in the off-state, the voltage of C1 is: (t) I ESR (t) I 2R V V (t) V OFFOFFON - DSINOUT OFF - C × + ×+ − The average of VC1 during the off-state is: The difference in charge stored in C 1 between the on-state and off-state is the net charge transferred to the output in one cycle.

www.SiliconStandard.com 11 of 13 SS6845G 7/21/2005 Rev.3.01 ]D) D(1 1I ESR)(2R V [2V C )D - 1 IESR -D IESR -D 1 I2RD I2R V (2V C ) I ESR - I ESR - I 2R - I 2R - V - (2V C )V(V C Q - Q Q OUTON DSOUTIN1 OUTOUTOUT ON DS OUT ON DSOUTIN1 AVE - OFFAVE ONAVE - OFFON - DSAVE - ON ON - DSOUTIN1 AVE OFF C1AVE ON C1 1 OFFON −× = = ∆ − −− − ………(13) Thus the output current can be written as ]D) - D(1 1I ) ESR(2R - V [2V C f ) Q (Q f Q f I OUTON - DSOUTIN1 OFFONOUT − × = ∆ × = (14) When the duty cycle is 0.5, the output current can be written as: ] I 4ESR)(8R V [2V fC ]0.5) 0.5(1 1I ESR)(2R V [2V C f I OUTON DSOUTIN 1 OUTON DSOUTIN 1OUT × +− − × = − (15) And equation (15) can be re-written as: OUTON DSOUT OUTIN I 4ESR)(8R IfC VOUT 2VIN COUT 1/fC1 8RDS-ON IOUT LOAD 4ESR Fig. 22 The equivalent circuit of charge pump According to equation (16), when the duty cycle is 0.5, the equivalent circuit of the charge pump is shown in Fig. 22. The term 8R DS-ON is the total effect of switching resistance, 1/fC 1 is the effect of flying capacitor and 4ESR is its equivalent resistance. From the equivalent circuit shown in Fig. 22, it is seen that the terms 1/fC 1, 4ESR and 8R DS-ON should be as small as possible to get large output current. However, since the R DS-ON is internal to the SS6845G, all that can be done is to lower the values of 1/fC1 and ESR. However even if the values of 1/fC1 and ESR can be kept as small as possible, the term 8R DS-ON still dominates the limit of the maximum output current. Layout Considerations With the high switching frequency and transient currents of the SS6845G, careful consideration of PCB layout is important. To achieve the best performance, it is necessary to minimize the distance between every component and also to minimize the length of every connection and maximize the trace width. Make sure each device connects to an immediate ground plane. Fig. 23 to Fig. 25 show a recommended layout.

www.SiliconStandard.com 12 of 13 SS6845G 7/21/2005 Rev.3.01 Fig. 23 Top layer Fig. 24 Bottom layer Fig. 25 Topover layer APPLICATION EXAMPLES VOUT1 GND2 SHDN3 CAP- VIN CAP+ U1 SS6845G VIN CIN 2.2µ CFLY1 0.22µF VOUT COUT 2.2µF VOUT1 GND2 SHDN3 CAP- 4 VIN 5 CAP+ 6 U2 SS6845G CFLY2 0.22µF VSHDN CIN, COUT : TAIYO YUDEN Ceramic Capacitor, CELMK212BJ225MG (X5R) (0805) CFLY1, CFLY2: TAIYO YUDEN Ceramic Capacitor, CEEMK212BJ224KG (X7R) (0805) Fig. 26 Using two SS6845G in parallel to provide larger output current. VOUT1 GND2 SHDN3 CAP- 4 VIN 5 CAP+ 6 U1 SS6845G USB CIN 2.2µF CFLY 0.22µF VOUT COUT 2.2µF VSHDN CIN, COUT: TAIYO YUDEN Ceramic Capacitor, CELMK212BJ225MG (X5R) (0805) CF L Y 1 : TAIYO YUDEN Ceramic Capacitor, CEEMK212BJ224KG (X7R) (0805) Fig. 27 Regulated 5V from USB SS6845G

Information furnished by Silicon Standard Corporation is believed to be accurate and reliable. However, Silicon Standard Corporation makes no guarantee or warranty, express or implied, as to the reliability, accuracy, timeliness or completeness of such information and assumes no responsibility for its use, or for infringement of any patent or other intellectual property rights of third parties that may result from its use. Silicon Standard reserves the right to make changes as it deems necessary to any products described herein for any reason, including without limitation enhancement in reliability, functionality or design. No license is granted, whether expressly or by implication, in relation to the use of any products described herein or to the use of any information provided herein, under any patent or other intellectual property rights of Silicon Standard Corporation or any third parties. www.SiliconStandard.com 13 of 13 SS6845G 7/21/2005 Rev.3.01 PHYSICAL DIMENSIONS (unit: mm) c A b WITH PLATING SEATING PLANE GAUGE PLANE 0.25 SECTION A-A BASE METAL D E AA SEE VIEW B e 0.90 0.30 1.50 2.60 2.80 0.08 0.30 0.05 e θ L c E D b

0.95 BSC

0.60

1.90 BSC

0.60 REF

1.30 1 .70 3 .00 3 .00 0 .22 0 .50 0 .15 0 .95 1.45 M IN. S Y M B O L A M AX. SOT-23-6 MI LLIME TERS θL1 L VIEW B PART MARKING PART NUMBER CODE: BO50P = SS6845GG BO50P PACKING: Moisture sensitivity level MSL3 3000 pcs in antistatic tape on a reel packed in a moisture barrier bag (MBB).