LT1054L

LT1054/LT1054L Switched-Capacitor Voltage Converter with Regulator FEATURES s s DESCRIPTIO s s s s s s s Available in Space Saving SO-8 Package Output Current: 100mA (LT1054) 125mA (LT1054L) Reference and Error Amplifier for Regulation Low Loss: 1.1V at 100mA Operating Range:3.5V to 15V (LT1054) 3.5V to 7V (LT1054L) External Shutdown External Oscillator Synchronization Can Be Paralleled Pin Compatible with the LTC®1044/LTC7660 The LT ®1054 is a monolithic, bipolar, switched-capacitor voltage converter and regulator. The LT1054 provides higher output current than previously available converters with significantly lower voltage losses. An adaptive switch driver scheme optimizes efficiency over a wide range of output currents. Total voltage loss at 100mA output current is typically 1.1V. This holds true over the full supply voltage range of 3.5V to 15V. Quiescent current is typically 2.5mA. The LT1054 also provides regulation, a feature not previously available in switched-capacitor voltage converters. By adding an external resistive divider a regulated output can be obtained. This output will be regulated against changes in both input voltage and output current. The LT1054 can also be shut down by grounding the feedback pin. Supply current in shutdown is less than 100µA. The internal oscillator of the LT1054 runs at a nominal frequency of 25kHz. The oscillator pin can be used to adjust the switching frequency or to externally synchronize the LT1054. The LT1054 is pin compatible with previous converters such the LTC1044/LTC7660. APPLICATIO S s s s s Voltage Inverter Voltage Regulator Negative Voltage Doubler Positive Voltage Doubler , LTC and LT are registered trademarks of Linear Technology Corporation. BLOCK DIAGRA VREF 6 2.5V R VIN 8 2 REFERENCE DRIVE + 1 FEEDBACK/ SHUTDOWN VOLTAGE LOSS (V) + – OSC R 7 OSC Q Q CAP + 2 CIN* CAP – 4 DRIVE DRIVE 3 GND *EXTERNAL CAPACITORS + COUT* 5 –VOUT DRIVE LT1054 • BD U LT1054/LT1054L Voltage Loss 3.5V ≤ VIN ≤ 15V (LT1054) 3.5V ≤ VIN ≤ 7V (LT1054L) CIN = COUT = 100µF INDICATES GUARANTEED TEST POINT LT1054 1 TJ = 125°C TJ = 25°C TJ = – 55°C 0 LT1054L 0 25 50 75 100 OUTPUT CURRENT (mA) 125 1054 TA01• W U 1054lfe 1 LT1054/LT1054L ABSOLUTE AXI U RATI GS Supply Voltage (Note 2) LT1054 ................................................................ 16V LT1054L ................................................................ 7V Input Voltage Pin 1 ................................................. 0V ≤ VPIN1 ≤ V+ Pin 3 (S Package) ............................. 0V ≤ VPIN3 ≤ V+ Pin 7 ............................................. 0V ≤ VPIN7 ≤ VREF Pin 13 (S Package) ...................... 0V ≤ VPIN13 ≤ VREF Operating Junction Temperature Range LT1054C/LT1054LC ............................. 0°C to 100°C LT1054I ........................................... – 40°C to 100°C PACKAGE/ORDER I FOR ATIO TOP VIEW FB/SHDN 1 FB/SHDN 1 CAP + 2 GND 3 CAP – 4 8 7 6 5 V+ OSC VREF VOUT CAP + 2 GND 3 CAP – 4 N8 PACKAGE 8-LEAD PLASTIC DIP S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 125°C, θJA = 120°C/W SEE REGULATION AND CAPACITOR SELECTION SECTIONS IN THE APPLICATIONS INFORMATION FOR IMPORTANT INFORMATION ON THE S8 DEVICE TJMAX = 125°C, θJA = 130°C/ W (N8) ORDER PART NUMBER LT1054CN8 LT1054IN8 J8 PACKAGE 8-LEAD CERAMIC DIP ORDER PART NUMBER LT1054CS8 LT1054LCS8 LT1054IS8 S8 PART MARKING 1054 1054L 1054I TJMAX = 150°C, θJA = 100°C/ W (J8) LT1054CJ8 LT1054MJ8 OBSOLETE PACKAGE Consider N8 Package for Alternate Source 2 U U W WW U W (Note 1) Maximum Junction Temperature (Note 3) LT1054C/LT1054LC ........................................ 125°C LT1054I ............................................................ 125°C Storage Temperature Range J8, N8 and S8 Packages .................... –55°C to 150°C S Package ........................................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C (Note 6) TOP VIEW TOP VIEW 8 7 6 5 V+ OSC VREF VOUT NC 1 NC 2 FB/SHDN 3 CAP + 4 16 NC 15 NC 14 V + 13 OSC 12 VREF 11 VOUT 10 NC 9 SW PACKAGE 16-LEAD PLASTIC SO NC GND 5 CAP – 6 NC 7 NC 8 TJMAX = 125°C, θJA = 150°C/W ORDER PART NUMBER LT1054CSW LT1054ISW 1054lfe LT1054/LT1054L ELECTRICAL CHARACTERISTICS PARAMETER Supply Current CONDITIONS ILOAD = 0mA The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 7) MIN VIN = 3.5V VIN = 15V LT1054L: VIN = 3.5V VIN = 7V LT1054: q q q q q q q q q q q q q TYP 2.5 3.0 2.5 3.0 Supply Voltage Range Voltage Loss (VIN – VOUT) Output Resistance Oscillator Frequency Reference Voltage Regulated Voltage Line Regulation Load Regulation Maximum Switch Current Supply Current in Shutdown LT1054 LT1054L CIN = COUT = 100µF Tantalum (Note 4) IOUT = 10mA IOUT = 100mA IOUT = 125mA (LT1054L) ∆IOUT = 10mA to 100mA (Note 5) LT1054: 3.5V ≤ VIN ≤ 15V LT1054L: 3.5V ≤ VIN ≤ 7V IREF = 60µA, TJ = 25°C VIN = 7V, TJ = 25°C, RL = 500Ω (Note 6) LT1054: 7V ≤ VIN ≤ 12V, RL = 500Ω (Note 6) VIN = 7V, 100Ω ≤ RL ≤ 500Ω (Note 6) VPIN1 = 0V 3.5 3.5 0.35 1.10 1.35 10 25 25 2.50 – 5.00 5 10 300 100 MAX 4.0 5.0 4.0 5.0 15 7 0.55 1.60 1.75 15 40 35 2.65 2.75 – 5.20 25 50 200 UNITS mA mA mA mA V V V V V Ω kHz kHz V V V mV mV mA µA 15 15 2.35 2.25 – 4.70 q q q Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The absolute maximum supply voltage rating of 16V is for unregulated circuits using LT1054. For regulation mode circuits using LT1054 with VOUT ≤ 15V at Pin 5 (Pin 11 on S package), this rating may be increased to 20V. The absolute maximum supply voltage for LT1054L is 7V. Note 3: The devices are guaranteed by design to be functional up to the absolute maximum junction temperature. Note 4: For voltage loss tests, the device is connected as a voltage inverter, with pins 1, 6, and 7 (3, 12, and 13 S package) unconnected. The voltage losses may be higher in other configurations. Note 5: Output resistance is defined as the slope of the curve, (∆VOUT vs ∆IOUT), for output currents of 10mA to 100mA. This represents the linear portion of the curve. The incremental slope of the curve will be higher at currents < 10mA due to the characteristics of the switch transistors. Note 6: All regulation specifications are for a device connected as a positive-to-negative converter/regulator with R1 = 20k, R2 = 102.5k, C1 = 0.002µF, (C1 = 0.05µF S package) CIN = 10µF tantalum, COUT = 100µF tantalum. Note 7: The S8 package uses a different die than the H, J8, N8 and S packages. The S8 device will meet all the existing data sheet parameters. See Regulation and Capacitor Selection in the Applications Information section for differences in application requirements. 1054lfe 3 LT1054/LT1054L TYPICAL PERFOR A CE CHARACTERISTICS Shutdown Threshold 0.6 0.5 SHUTDOWN THRESHOLD (V) SUPPLY CURRENT (mA) VPIN1 0.4 0.3 0.2 0.1 0 – 50 – 25 3 FREQUENCY (kHz) 50 25 75 0 TEMPERATURE (˚C) Supply Current in Shutdown 120 AVERAGE INPUT CURRENT (mA) 140 120 100 QUIESCENT CURRENT (µA) 80 60 40 20 0 80 60 40 20 0 0 20 60 80 40 OUTPUT CURRENT (mA) 100 VOLTAGE LOSS (V) VPIN1 = 0V 0 10 5 INPUT VOLTAGE (V) Output Voltage Loss INVERTER CONFIGURATION CIN = 10µF TANTALUM COUT = 100µF TANTALUM 2 VOLTAGE LOSS (V) IOUT = 100mA VOLTAGE LOSS (V) 1 0 1 10 OSCILLATOR FREQUENCY (kHz) 100 4 UW 100 LT1054 • TPC01 Supply Current 5 IL = 0 4 35 Oscillator Frequency 25 VIN = 3.5V VIN = 15V 2 1 0 125 0 10 5 INPUT VOLTAGE (V) 15 LT1054 • TPC02 15 –70 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 LT1054 • TPC03 Average Input Current 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 Output Voltage Loss IOUT = 100mA 100 IOUT = 50mA IOUT = 10mA INVERTER CONFIGURATION COUT = 100µF TANTALUM fOSC = 25kHz 0 10 20 30 40 50 60 70 80 90 100 INPUT CAPACITANCE (µF) LT1054 • TPC06 15 LT1054 • TPC04 LT1050 • TPC05 Output Voltage Loss INVERTER CONFIGURATION CIN = 100µF TANTALUM COUT = 100µF TANTALUM 2 IOUT = 100mA 1 IOUT = 50mA IOUT = 10mA 0 1 10 OSCILLATOR FREQUENCY (kHz) 100 IOUT = 50mA IOUT = 10mA LT1054 • TPC07 LT1054 • TPC08 1054lfe LT1054/LT1054L TYPICAL PERFOR A CE CHARACTERISTICS Regulated Output Voltage –4.7 100 –4.9 REFERENCE VOLTAGE CHANGE (mV) –4.8 OUTPUT VOLTAGE (V) –5.0 –5.1 –11.6 –11.8 –12.0 –12.2 –12.4 –12.6 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 PIN FUNCTIONS FB/SHDN (Pin 1): Feedback/Shutdown Pin. This pin has two functions. Pulling Pin 1 below the shutdown threshold (≈ 0.45V) puts the device into shutdown. In shutdown the reference/regulator is turned off and switching stops. The switches are set such that both CIN and COUT are discharged through the output load. Quiescent current in shutdown drops to approximately 100µA (see Typical Performance Characteristics). Any open-collector gate can be used to put the LT1054 into shutdown. For normal (unregulated) operation the device will start back up when the external gate is shut off. In LT1054 circuits that use the regulation feature, the external resistor divider can provide enough pull-down to keep the device in shutdown until the output capacitor (COUT) has fully discharged. For most applications where the LT1054 would be run intermittently, this does not present a problem because the discharge time of the output capacitor will be short compared to the offtime of the device. In applications where the device has to start up before the output capacitor (COUT) has fully discharged, a restart pulse must be applied to Pin 1 of the LT1054. Using the circuit of Figure 5, the restart signal can be either a pulse (tp > 100µs) or a logic high. Diode coupling the restart signal into Pin 1 will allow the output voltage to come up and regulate without overshoot. The resistor divider R3/R4 in Figure 5 should be chosen to provide a signal level at pin 1 of 0.7V to 1.1V. Pin 1 is also the inverting input of the LT1054’s error amplifier and as such can be used to obtain a regulated output voltage. CAP +/CAP – (Pin 2/Pin 4): Pin 2, the positive side of the input capacitor (CIN), is alternately driven between V + and ground. When driven to V +, Pin 2 sources current from V +. When driven to ground Pin 2 sinks current to ground. Pin 4, the negative side of the input capacitor, is driven alternately between ground the VOUT. When driven to ground, Pin 4 sinks current to ground. When driven to VOUT Pin 4 sources current from COUT. In all cases current flow in the switches is unidirectional as should be expected using bipolar switches. VOUT (Pin 5): In addition to being the output pin this pin is also tied to the substrate of the device. Special care must be taken in LT1054 circuits to avoid pulling this pin positive with respect to any of the other pins. Pulling Pin 5 positive with respect to Pin 3 (GND) will forward bias the substrate diode which will prevent the device from starting. This condition can occur when the output load driven by the LT1054 is referred to its positive supply (or to some other positive voltage). Note that most op amps present just such a load since their supply currents flow from their V + terminals to their V – terminals. To prevent start-up problems with this type of load an external transistor must be added as shown in Figure 1. This will prevent VOUT (Pin 5) 1054lfe UW Reference Voltage Temperature Coefficient 80 60 40 20 0 –20 –40 –60 –80 50 25 0 75 TEMPERATURE (°C) 100 125 VREF AT 0 = 2.500V –100 –50 –25 LT1054 • TPC09 LT1054 • TPC10 U U U 5 LT1054/LT1054L PIN FUNCTIONS from being pulled above the ground pin (Pin 3) during start-up. Any small, general purpose transistor such as 2N2222 or 2N2219 can be used. RX should be chosen to provide enough base drive to the external transistor so that it is saturated under nominal output voltage and maximum output current conditions. In some cases an N-channel enhancement mode MOSFET can be used in place of the transistor. RX ≤ (|VOUT|)β IOUT V+ FB/SHDN V+ RX + CIN OSC CAP + LT1054 GND VREF CAP – VOUT Figure 1 Figure 2 V + (Pin 8): Input Supply. The LT1054 alternately charges CIN to the input voltage when CIN is switched in parallel with the input supply and then transfers charge to COUT when CIN is switched in parallel with COUT. Switching occurs at 1054lfe 6 + VREF (Pin 6): Reference Output. This pin provides a 2.5V reference point for use in LT1054-based regulator circuits. The temperature coefficient of the reference voltage has been adjusted so that the temperature coefficient of the regulated output voltage is close to zero. This requires the reference output to have a positive temperature coefficient as can be seen in the typical performance curves. This nonzero drift is necessary to offset a drift term inherent in the internal reference divider and comparator network tied to the feedback pin. The overall result of these drift terms is a regulated output which has a slight positive temperature coefficient at output voltages below 5V and a slight negative TC at output voltages above 5V. Reference output current should be limited, for regulator feedback networks, to approximately 60µA. The reference pin will draw ≈ 100µA when shorted to ground and will not affect the internal reference/regulator, so that this pin can also be used as a pull-up for LT1054 circuits that require synchronization. + U U U OSC (Pin 7): Oscillator Pin. This pin can be used to raise or lower the oscillator frequency or to synchronize the device to an external clock. Internally Pin 7 is connected to the oscillator timing capacitor (Ct ≈ 150pF) which is alternately charged and discharged by current sources of ± 7µA so that the duty cycle is ≈ 50%. The LT1054 oscillator is designed to run in the frequency band where switching losses are minimized. However the frequency can be raised, lowered, or synchronized to an external system clock if necessary. The frequency can be lowered by adding an external capacitor (C1, Figure 2) from Pin 7 to ground. This will increase the charge and discharge times which lowers the oscillator frequency. The frequency can be increased by adding an external capacitor (C2, Figure 2, in the range of 5pF to 20pF) from Pin 2 to Pin 7. This capacitor will couple charge into CT at the switch transitions, which will shorten the charge and discharge time, raising the oscillator frequency. Synchronization can be accomplished by adding an external resistive pull-up from Pin 7 to the reference pin (Pin 6). A 20k pull-up is recommended. An open collector gate or an NPN transistor can then be used to drive the oscillator pin at the external clock frequency as shown in Figure 2. Pulling up Pin 7 to an external voltage is not recommended. For circuits that require both frequency synchronization and regulation, an external reference can be used as the reference point for the top of the R1/R2 divider allowing Pin 6 to be used as a pull-up point for Pin 7. IL LOAD + – IQ IOUT LT1054 • F01 COUT FB/SHDN V + VIN C2 + CIN OSC CAP LT1054 GND VREF CAP – + C1 VOUT COUT LT1054 • F02 LT1054/LT1054L PIN FUNCTIONS the oscillator frequency. During the time that CIN is charging, the peak supply current will be approximately equal to 2.2 times the output current. During the time that CIN is delivering charge to COUT the supply current drops to approximately 0.2 times the output current. An input supply bypass capacitor will supply part of the peak input current drawn by the LT1054 and average out the current drawn from the supply. A minimum input supply bypass capacitor of 2µF, preferably tantalum or some other low ESR type is recommended. A larger capacitor may be desirable in some cases, for example, when the actual input supply is connected to the LT1054 through long leads, or when the pulse current drawn by the LT1054 might affect other circuitry through supply coupling. APPLICATIONS INFORMATION Theory of Operation To understand the theory of operation of the LT1054, a review of a basic switched-capacitor building block is helpful. In Figure 3 when the switch is in the left position, capacitor C1 will charge to voltage V1. The total charge on C1 will be q1 = C1V1. The switch then moves to the right, discharging C1 to voltage V2. After this discharge time the charge on C1 is q2 = C1V2. Note that charge has been transferred from the source V1 to the output V2. The amount of charge transferred is: ∆q = q1 – q2 = C1(V1 – V2) If the switch is cycled f times per second, the charge transfer per unit time (i.e., current) is: I = (f)(∆q) = (f)[C1(V1 – V2)] To obtain an equivalent resistance for the switched-capacitor network we can rewrite this equation in terms of voltage and impedance equivalence: I = V1 – V2 = V1 – V2 (1/fC1) REQUIV REQUIV V1 REQUIV = 1 fC1 C2 RL LT1054 • F04 A new variable REQUIV is defined such that REQUIV = 1/fC1. Thus the equivalent circuit for the switched-capacitor network is as shown in Figure 4. The LT1054 has the same switching action as the basic switched-capacitor building block. Even though this simplification doesn’t include finite switch on-resistance and output voltage ripple, it provides an intuitive feel for how the device works. These simplified circuits explain voltage loss as a function of frequency (see Typical Performance Characteristics). As frequency is decreased, the output impedance will eventu- U W U U U U U V1 f C1 C2 RL V2 LT1054 • F03 Figure 3. Switched-Capacitor Building Block V2 Figure 4. Switched-Capacitor Equivalent Circuit ally be dominated by the 1/fC1 term and voltage losses will rise. Note that losses also rise as frequency increases. This is caused by internal switching losses which occur due to some finite charge being lost on each switching cycle. This charge loss per-unit-cycle, when multiplied by the switching frequency, becomes a current loss. At high frequency this loss becomes significant and voltage losses again rise. The oscillator of the LT1054 is designed to run in the frequency band where voltage losses are at a minimum. Regulation The error amplifier of the LT1054 servos the drive to the PNP switch to control the voltage across the input capacitor (CIN) which in turn will determine the output voltage. Using the reference and error amplifier of the LT1054, an external resistive divider is all that is needed to set the regulated output voltage. Figure 5 shows the basic regulator configuration and the formula for calculating the appropriate resistor values. R1 should be chosen to be 1054lfe 7 LT1054/LT1054L APPLICATIONS INFORMATION R3 FB/SHDN R4 CIN 10µF TANTALUM V+ + OSC CAP + LT1054 GND VREF CAP – VOUT FOR EXAMPLE: TO GET VOUT = – 5V REFERRED TO THE GROUND PIN OF THE LT1054, CHOOSE R1 = 20k, THEN R2 = 20k |–5V| + 1 = 102.6k* 2.5V – 40mV 2 *CHOOSE THE CLOSEST 1% VALUE ) ) Figure 5 20k or greater because the reference output current is limited to ≈ 100µA. R2 should be chosen to be in the range of 100k to 300k. For optimum results the ratio of CIN/COUT is recommended to be 1/10. C1, required for good load regulation at light load currents, should be 0.002µF for all output voltages. A new die layout was required to fit into the physical dimensions of the S8 package. Although the new die of the LT1054CS8 will meet all the specifications of the existing LT1054 data sheet, subtle differences in the layout of the new die require consideration in some application circuits. In regulating mode circuits using the 1054CS8 the nominal values of the capacitors, CIN and COUT, must be approximately equal for proper operation at elevated junction temperatures. This is different from the earlier part. Mismatches within normal production tolerances for the capacitors are acceptable. Making the nominal capacitor values equal will ensure proper operation at elevated junction temperatures at the cost of a small degradation in the transient response of regulator circuits. For unregulated circuits the values of CIN and COUT are normally equal for all packages. For S8 applications assistance in unusual applications circuits, please consult the factory. It can be seen from the circuit block diagram that the maximum regulated output voltage is limited by the supply 8 + |VOUT| |VOUT| R2 = +1 ≈ +1 1.21V VREF R1 – 40mV 2 WHERE VREF = 2.5V NOMINAL ) RESTART SHUTDOWN )) ) VOUT COUT 100µF TANTALUM LT1054 • F05 + VIN U W U U 2.2µF R1 R2 C1 voltage. For the basic configuration, |VOUT| referred to the ground pin of the LT1054 must be less than the total of the supply voltage minus the voltage loss due to the switches. The voltage loss versus output current due to the switches can be found in Typical Performance Characteristics. Other configurations such as the negative doubler can provide higher output voltages at reduced output currents (see Typical Applications). Capacitor Selection For unregulated circuits the nominal values of CIN and COUT should be equal. For regulated circuits see the section on Regulation. While the exact values of CIN and COUT are noncritical, good quality, low ESR capacitors such as solid tantalum are necessary to minimize voltage losses at high currents. For CIN the effect of the ESR of the capacitor will be multiplied by four due to the fact that switch currents are approximately two times higher than output current and losses will occur on both the charge and discharge cycle. This means that using a capacitor with 1Ω of ESR for CIN will have the same effect as increasing the output impedance of the LT1054 by 4Ω. This represents a significant increase in the voltage losses. For COUT the affect of ESR is less dramatic. COUT is alternately charged and discharged at a current approximately equal to the output current and the ESR of the capacitor will cause a step function to occur in the output ripple at the switch transitions. This step function will degrade the output regulation for changes in output load current and should be avoided. Realizing that large value tantalum capacitors can be expensive, a technique that can be used is to parallel a smaller tantalum capacitor with a large aluminum electrolytic capacitor to gain both low ESR and reasonable cost. Where physical size is a concern some of the newer chip type surface mount tantalum capacitors can be used. These capacitors are normally rated at working voltages in the 10V to 20V range and exhibit very low ESR (in the range of 0.1Ω). Output Ripple The peak-to-peak output ripple is determined by the value of the output capacitor and the output current. Peak-topeak output ripple may be approximated by the formula: dV = IOUT 2fCOUT 1054lfe LT1054/LT1054L APPLICATIONS INFORMATION where dV = peak-to-peak ripple and f = oscillator frequency. For output capacitors with significant ESR a second term must be added to account for the voltage step at the switch transitions. This step is approximately equal to: (2IOUT)(ESR of COUT) Power Dissipation The power dissipation of any LT1054 circuit must be limited such that the junction temperature of the device does not exceed the maximum junction temperature ratings. The total power dissipation must be calculated from two components, the power loss due to voltage drops in the switches and the power loss due to drive current losses. The total power dissipated by the LT1054 can be calculated from: P ≈ (VIN – |VOUT|)(IOUT) + (VIN)(IOUT)(0.2) where both VIN and VOUT are referred to the ground pin (Pin 3) of the LT1054. For LT1054 regulator circuits, the power dissipation will be equivalent to that of a linear regulator. Due to the limited power handling capability of the LT1054 packages, the user will have to limit output current requirements or take steps to dissipate some power external to the LT1054 for large input/output differentials. This can be accomplished by placing a resistor in series with CIN as shown in Figure 6. A portion of the input voltage will then be dropped across this resistor without affecting the output regulation. Because switch current is approximately 2.2 times the output current and the resistor will cause a voltage drop when CIN is both charging and discharging, the resistor should be chosen as: VIN FB/SHDN V + RX + CIN OSC CAP + LT1054 GND VREF CAP – VOUT R1 R2 C1 VOUT COUT LT1054 • F06 Figure 6 1054lfe U W + U U RX = VX/(4.4 IOUT) where VX ≈ VIN – [(LT1054 Voltage Loss)(1.3) + |VOUT|] and IOUT = maximum required output current. The factor of 1.3 will allow some operating margin for the LT1054. For example: assume a 12V to – 5V converter at 100mA output current. First calculate the power dissipation without an external resistor: P = (12V – | – 5V|)(100mA) + (12V)(100mA)(0.2) P = 700mW + 240mW = 940mW At θJA of 130°C/W for a commercial plastic device this would cause a junction temperature rise of 122°C so that the device would exceed the maximum junction temperature at an ambient temperature of 25°C. Now calculate the power dissipation with an external resistor (RX). First find how much voltage can be dropped across RX. The maximum voltage loss of the LT1054 in the standard regulator configuration at 100mA output current is 1.6V, so VX = 12V – [(1.6V)(1.3) + | – 5V|] = 4.9V and RX = 4.9V/(4.4)(100mA) = 11Ω This resistor will reduce the power dissipated by the LT1054 by (4.9V)(100mA) = 490mW. The total power dissipated by the LT1054 would then be (940mW – 490mW) = 450mW. The junction temperature rise would now be only 58°C. Although commercial devices are guaranteed to be functional up to a junction temperature of 125°C, the specifications are only guaranteed up to a junction temperature of 100°C, so ideally you should limit the junction temperature to 100°C. For the above example this would mean limiting the ambient temperature to 42°C. Other steps can be taken to allow higher ambient temperatures. The thermal resistance numbers for the LT1054 packages represent worst case numbers with no heat sinking and still air. Small clip-on type heat sinks can be used to lower the thermal resistance of the LT1054 package. In some systems there may be some available airflow which will help to lower the thermal resistance. Wide PC board traces from the LT1054 leads can also help to remove heat from the device. This is especially true for plastic packages. 9 LT1054/LT1054L TYPICAL APPLICATIONS N Basic Voltage Inverter FB/SHDN V + 100µF + + –VOUT 100µF LT1054 • TAO2 CAP – VOUT 10µF OSC CAP + LT1054 GND VREF CAP – VOUT VOUT REFER TO FIGURE 5 Negative Voltage Doubler Positive Doubler FB/SHDN V + OSC CAP LT1054 GND VREF CAP – + + VOUT 100µF + – QX* 100µF RX* 1N4001 VOUT 50mA VIN 1N4001 3.5V TO 15V + – VIN 2µF + 100µF + 10µF FB/SHDN V + OSC CAP + LT1054 GND VREF CAP – VOUT VOUT + VIN = 3.5V TO 15V VOUT ≈ 2VIN – (VL + 2VDIODE) VL = LT1054 VOLTAGE LOSS VIN VIN = – 3.5V TO –15V VOUT = 2VIN + (LT1054 VOLTAGE LOSS) + (QX SATURATION VOLTAGE) LT1054 • TAO4 *SEE FIGURE 3 100mA Regulating Negative Doubler VIN 3.5 TO 15V + 2.2µF FB/SHDN V + FB/SHDN V + VOUT SET R1 40k 0.002µF HP5082-2810 20k PIN 2 LT1054 #1 10µF + 10µF 1N4002 + OSC CAP LT1054 #1 GND VREF CAP – VOUT 10µF + 10µF + 10µF 1N4002 + OSC CAP LT1054 #2 GND VREF CAP – VOUT + 1N4002 100µF VIN = 3.5 TO 15V VOUT MAX ≈ – 2VIN + [1054 VOLTAGE LOSS + 2(VDIODE)] –VOUT IOUT ≅ 100mA MAX LT1054 • TAO6 |VOUT| |VOUT| R2 = +1 = + 1 , REFER TO FIGURE 5 1.21V R1 VREF – 40mV 2 1054lfe ) )) ) 10 + 1N4002 R2 500k 1N4002 10µF + |VOUT| |VOUT| R2 = +1 = +1 , 1.21V R1 VREF – 40mV 2 ) )) ) + OSC CAP + LT1054 GND VREF + + U Basic Voltage Inverter/Regulator + VIN 2µF FB/SHDN V+ VIN 2µF R1 R2 0.002µF 100µF LT1054 • TA03 + 2µF + LT1054 • TAO5 + LT1054/LT1054L TYPICAL APPLICATIONS N Bipolar Supply Doubler VIN 3.5V TO 15V +VOUT = 1N4001 5V to ± 12V Converter VIN = 5V + 5µF + FB/SHDN V + VOUT ≈ 12V IOUT = 25mA 1N914 1N914 + 10µF + OSC CAP LT1054 #1 GND VREF CAP – VOUT 2N2219 1k 100µF + + 10µF FB/SHDN V + OSC CAP + LT1054 #2 GND VREF CAP – VOUT 10µF 20k VOUT ≈ –12V IOUT = 25mA LT1054 • TAO8 Strain Gauge Bridge Signal Conditioner 10k INPUT TTL OR CMOS LOW FOR ON 10k 2N2907 5V + 40Ω 10k ZERO TRIM 10µF 1 A1 1/2 LT1013 301k 3 100k 350Ω 10k 1µF 5 200k FB/SHDN V + 5V 3k 2N2222 + 10µF OSC CAP + LT1054 GND VREF CAP – VOUT + 100µF TANTALUM A = 125 FOR 0V TO 3V OUT FROM FULL-SCALE BRIDGE OUTPUT OF 24mV + – – 0.022µF 8 2 100k 5k 5k GAIN TRIM 6 1M 7 A2 1/2 LT1013 4 + + + 100µF 5µF + + VIN = 3.5V TO 15V +VOUT ≈ 2VIN – (VL + 2VDIODE) –VOUT ≈ – 2VIN + (VL + 2VDIODE) VL = LT1054 VOLTAGE LOSS 100µF – + U + – + 100µF + 10µF FB/SHDN V + OSC CAP + LT1054 GND VREF CAP – VOUT + + 10µF 100µF 10µF + –VOUT LT1054 • TAO7 TO PIN 4 LT1054 #1 100µF LT1054 • TAO9 1054lfe 11 LT1054/LT1054L TYPICAL APPLICATIONS N VIN 3.5V TO 5.5V 20k 1N914 1N914 FB/SHDN V + 1N914 + 10µF R2 125k 2N2219 100µF 3k VOUT = 5V VIN = 3.5V TO 5.5V VOUT = 5V IOUT(MAX) = 50mA 1N5817 1N914 LT1054 • TA10 Regulating 200mA, 12V to – 5V Converter 5µF 12V FB/SHDN V + OSC CAP + LT1054 #1 GND VREF CAP – VOUT R1 39.2k R2 200k 200µF VOUT = –5V IOUT = 0mA to 200mA FB/SHDN V + HP5082-2810 10Ω 1/2W + 10µF 10µF 0.002µF + 10Ω 1/2W OSC CAP + LT1054 #2 GND VREF CAP – VOUT 20k REFER TO FIGURE 5 Digitally Programmable Negative Supply 15V + 5µF 20k LT1004-2.5 2.5V 20k 14 16 FB/SHDN V + 10µF + OSC CAP + LT1054 GND VREF CAP – VOUT VOUT = – VIN (PROGRAMMED) 100µF 12 + |VOUT| |VOUT| R2 = +1 = +1 , 1.21V R1 VREF – 40mV 2 ) )) ) LT1054 • TA11 11 AD558 DIGITAL INPUT 13 12 LT1054 • TA12 + CAP – VOUT 0.002µF + + – + + U 3.5V to 5V Regulator 1 8 7 LTC1044 6 5 + + R1 20k 1µF 5µF R2 125k OSC CAP + LT1054 GND VREF 2 3 4 1µF 1054lfe LT1054/LT1054L PACKAGE DESCRIPTION J8 Package 8-Lead CERDIP (Narrow .300 Inch, Hermetic) (Reference LTC DWG # 05-08-1110) CORNER LEADS OPTION (4 PLCS) .405 (10.287) MAX 8 7 6 5 .045 – .068 (1.143 – 1.650) FULL LEAD OPTION .300 BSC (7.62 BSC) .008 – .018 (0.203 – 0.457) NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS U .005 (0.127) MIN .023 – .045 (0.584 – 1.143) HALF LEAD OPTION .025 (0.635) RAD TYP 1 2 3 .220 – .310 (5.588 – 7.874) 4 .200 (5.080) MAX .015 – .060 (0.381 – 1.524) 0° – 15° .045 – .065 (1.143 – 1.651) .014 – .026 (0.360 – 0.660) .100 (2.54) BSC .125 3.175 MIN J8 0801 OBSOLETE PACKAGE 1054lfe 13 LT1054/LT1054L PACKAGE DESCRIPTION N8 Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510) .400* (10.160) MAX 8 7 6 5 .300 – .325 (7.620 – 8.255) .008 – .015 (0.203 – 0.381) ( +.035 .325 –.015 8.255 +0.889 –0.381 ) INCHES MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm) NOTE: 1. DIMENSIONS ARE .050 BSC 8 .245 MIN .030 ±.005 TYP RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) 0°– 8° TYP NOTE: 1. DIMENSIONS IN INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) 14 U .255 ± .015* (6.477 ± 0.381) 1 2 3 4 .130 ± .005 (3.302 ± 0.127) .045 – .065 (1.143 – 1.651) .065 (1.651) TYP .120 (3.048) .020 MIN (0.508) MIN .018 ± .003 (0.457 ± 0.076) N8 1002 .100 (2.54) BSC S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 7 6 5 .045 ±.005 .160 ±.005 .228 – .244 (5.791 – 6.197) .150 – .157 (3.810 – 3.988) NOTE 3 1 2 3 4 .053 – .069 (1.346 – 1.752) .004 – .010 (0.101 – 0.254) .016 – .050 (0.406 – 1.270) .014 – .019 (0.355 – 0.483) TYP .050 (1.270) BSC SO8 0303 1054lfe LT1054/LT1054L PACKAGE DESCRIPTION SW Package 16-Lead Plastic Small Outline (Wide .300 Inch) (Reference LTC DWG # 05-08-1620) .030 ±.005 TYP N .420 MIN 1 2 3 RECOMMENDED SOLDER PAD LAYOUT 1 .291 – .299 (7.391 – 7.595) NOTE 4 .010 – .029 × 45° (0.254 – 0.737) 0° – 8° TYP 2 3 4 5 6 7 8 .005 (0.127) RAD MIN .009 – .013 (0.229 – 0.330) NOTE 3 .016 – .050 (0.406 – 1.270) NOTE: 1. DIMENSIONS IN INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS. THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS 4. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U .050 BSC .045 ±.005 .398 – .413 (10.109 – 10.490) NOTE 4 16 15 14 13 12 11 10 9 N .325 ±.005 NOTE 3 .394 – .419 (10.007 – 10.643) N/2 N/2 .093 – .104 (2.362 – 2.642) .037 – .045 (0.940 – 1.143) .050 (1.270) BSC .004 – .012 (0.102 – 0.305) .014 – .019 (0.356 – 0.482) TYP S16 (WIDE) 0502 1054lfe 15 LT1054/LT1054L TYPICAL APPLICATIONS N Positive Doubler with Regulation VIN = 5V 50k 1N5817 VOUT 8V 50mA + + 1N5817 0.03µF 5.5k 10µF 10k 5V 0.1µF LT1054 • TA13 |VOUT| |VOUT| R2 = +1 = + 1 , REFER TO FIGURE 5 1.21V R1 VREF – 40mV LT1054 • TA14 2 ) )) ) THE TYPICAL APPLICATIONS CIRCUITS WERE VERIFIED USING THE STANDARD LT1054. FOR S8 APPLICATIONS ASSISTANCE IN ANY OF THE UNUSUAL APPLICATIONS CIRCUITS PLEASE CONSULT THE FACTORY RELATED PARTS PART NUMBER LTC1144 LTC1514/LTC1515 LT1611 LT1614 LTC1911 DESCRIPTION Switched-Capacitor Wide Input Range Voltage Converter with Shutdown Step-Up/Step-Down Switched Capacitor DC/DC Converters 150mA Output, 1.4mHz Micropower Inverting Switching Regulator 250mA Output, 600kHz Micropower Inverting Switching Regulator 250mA, 1.5MHz Inductorless Step-Down DC/DC Converter COMMENTS Wide Input Voltage Range: 2V to 18V, ISD < 8µA, SO8 VIN: 2V to 10V, VOUT: 3.3V to 5V, IQ = 60µA, SO8 VIN: 0.9V to 10V, VOUT: ±34V ThinSOT VIN: 0.9V to 6V, VOUT: ±30V, IQ = 1mA, MS8, SO8 VIN: 2.7V to 5.5V, VOUT: 1.5V/1.8V, IQ = 180µA, MS8 VIN: 3.1V to 5.5V, VOUT: 1.2V, 1.5V, IQ = 35µA, ThinSOT™ LTC3250/LTC3250-1.2/ Inductorless Step-Down DC/DC Converter LTC3250-1.5 LTC3251 LTC3252 500mA Spread Spectrum Inductorless Step-Down DC/DC Converter VIN: 2.7V to 5.5V, VOUT: 0.9V to 1.6V, 1.2V, 1.5V, IQ = 9µA, MS10E Dual 250mA, Spread Spectrum Inductorless Step-Down DC/DC Converter VIN: 2.7V to 5.5V, VOUT: 0.9V to 1.6V, IQ = 50µA, DFN12 ThinSOT is a trademark of Linear Technology Corporation. 16 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 q FAX: (408) 434-0507 q LT/TP 0104 1K REV E • PRINTED IN USA www.linear.com © LINEAR TECHNOLOGY CORPORATION 1987 + + 2.5k – 10k 10µF 10k LT1006 1N4001 VIN = 3.5V TO 15V VOUT(MAX) ≈ – 2VIN + (VL + 2VDIODE) VL = LT1054 VOLTAGE LOSS + 100µF U Negative Doubler with Regulator VIN 3.5V TO 15V + FB/SHDN V + OSC CAP LT1054 GND VREF CAP – + 2µF FB/SHDN V + + 10µF + + OSC CAP LT1054 GND VREF CAP – VOUT + 2µF R1, 20k 100µF 1N4001 –VOUT 100µF R2 1M 0.002µF VOUT 1054lfe