LT1129/LT1129-3.3/LT1129-5 Micropower Low Dropout Regulators with Shutdown U FEATURES DESCRIPTIO ■ The LT®1129/LT1129-3.3/LT1129-5 are micropower low dropout regulators with shutdown. The devices are capable of supplying 700mA of output current with a dropout voltage of 0.4V at maximum output. Designed for use in battery-powered systems the low quiescent current, 50µA operating and 16µA in shutdown, make them an ideal choice. The quiescent current does not rise in dropout as it does with many other low dropout PNP regulators. ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 0.4V Dropout Voltage 700mA Output Current 50µA Quiescent Current No Protection Diodes Needed Adjustable Output from 3.8V to 30V 3.3V and 5V Fixed Output Voltages Controlled Quiescent Current in Dropout Shutdown 16µA Quiescent Current in Shutdown Stable with 3.3µF Output Capacitor Reverse Battery Protection No Reverse Output Current Thermal Limiting Surface Mount SOT-223 and DD Packages Other features of the LT1129 /LT1129-3.3/LT1129-5 include the ability to operate with small output capacitors. They are stable with only 3.3µF on the output while most older devices require between 10µF and 100µF for stability. Also the input may be connected to ground or a reverse voltage without reverse current flow from output to input. This makes the LT1129/LT1129-3.3/LT1129-5 ideal for backup power situations where the output is held high and the input is at ground or reversed. Under these conditions, only 16µA will flow from the output pin to ground. The devices are available in 5-lead TO-220, 5-lead DD and 3-lead SOT-223 packages. U APPLICATIO S ■ ■ ■ Low Current Regulator Regulator for Battery-Powered Systems Post Regulator for Switching Supplies 5V to 3.3V Logic Regulator , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. U ■ TYPICAL APPLICATIO 5V Supply with Shutdown Dropout Voltage 0.6 IN OUT 1 + LT1129-5 VIN > 5.5V 4 SENSE 5V OUT 500mA 2 3.3µF SOLID TANTALUM SHDN GND 3 VSHDN (PIN 4) OUTPUT < 0.25 OFF > 2.8 ON NC ON 0.5 DROPOUT VOLTAGE (V) 5 0.4 0.3 0.2 0.1 LT1129 • TA01 0 0 0.1 0.5 0.2 0.3 0.4 OUTPUT CURRENT (A) 0.6 0.7 LT1129 • TA02 112935fc 1 LT1129/LT1129-3.3/LT1129-5 U W W W ABSOLUTE AXI U RATI GS (Note 1) Input Voltage ...................................................... ± 30V* Output Pin Reverse Current ................................. 10mA Sense Pin Current ................................................ 10mA Adjust Pin Current ............................................... 10mA Shutdown Pin Input Voltage (Note 2) ........ 6.5V, – 0.6V Shutdown Pin Input Current (Note 2) .................. 20mA Output Short-Circuit Duration ......................... Indefinite Storage Temperature Range ................ – 65°C to 150°C Operating Junction Temperature Range (Note 2) LT1129C-X ......................................... 0°C to 125°C LT1129C-X Extended Temperature Range (Note 12) ........................................ –40°C to 125°C LT1129I-X ...................................... –40°C to 125°C Lead Temperature (Soldering, 10 sec).................. 300°C * For applications requiring input voltage ratings greater than 30V, contact the factory. U W U PACKAGE/ORDER I FOR ATIO TOP VIEW GND 1 20 GND GND 2 19 GND GND 3 18 GND GND 4 17 GND GND 5 16 GND GND 6 15 GND LT1129CF-3.3 TOP VIEW FRONT VIEW ORDER PART NUMBER TAB IS GND 5 VIN 4 SHDN 3 GND 2 SENSE/ADJ* OUTPUT 1 SENSE/ 2 ADJ* GND 3 7 GND 6 GND 5 SHDN NC 4 OUTPUT 1 8 VIN S8 PACKAGE 8-LEAD PLASTIC SO Q PACKAGE 5-LEAD PLASTIC DD OUT 7 14 IN SENSE 8 13 SHDN *PIN 2 = SENSE FOR LT1129-3.3/LT1129-5 = ADJ FOR LT1129 *PIN 2 = SENSE FOR LT1129-3.3/LT1129-5 = ADJ FOR LT1129 GND 9 12 GND θJA ≈ 30°C/ W θJA ≈ 60°C/ W GND 10 11 GND F PACKAGE 20-LEAD PLASTIC TSSOP NOTE: ALL GROUND PINS ARE INTERNALLY CONNECTED θJA ≈ 40°C/ W OBSOLETE PACKAGE FRONT VIEW TAB IS GND 3 OUTPUT 2 GND 1 VIN ST PACKAGE 3-LEAD PLASTIC SOT-223 θJA ≈ 50°C/ W ORDER PART NUMBER LT1129CST-3.3 LT1129CST-5 LT1129IST-3.3 LT1129IST-5 ORDER PART NUMBER ORDER PART NUMBER LT1129CQ LT1129CQ-3.3 LT1129CQ-5 LT1129IQ LT1129IQ-3.3 LT1129IQ-5 LT1129CS8 LT1129CS8-3.3 LT1129CS8-5 LT1129IS8 LT1129IS8-3.3 LT1129IS8-5 FRONT VIEW TAB IS GND 5 VIN 4 SHDN 3 GND 2 SENSE/ADJ* 1 OUTPUT T PACKAGE 5-LEAD PLASTIC TO-220 PART MARKING 1129 11293 11295 1129I 1129I3 1129I5 ORDER PART NUMBER LT1129CT LT1129CT-3.3 LT1129CT-5 LT1129IT LT1129IT-3.3 LT1129IT-5 *PIN 2 = SENSE FOR LT1129-3.3/LT1129-5 = ADJ FOR LT1129 θJA ≈ 50°C/ W Consult factory for Military grade parts. 112935fc 2 LT1129/LT1129-3.3/LT1129-5 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. PARAMETER CONDITIONS Regulated Output Voltage (Notes 4, 12) LT1129-3.3 LT1129-5 LT1129 (Note 5) Line Regulation (Note 12) LT1129-3.3 LT1129-5 LT1129 (Note 5) Load Regulation (Note 12) LT1129-3.3 LT1129-5 LT1129 (Note 5) Dropout Voltage (Note 6) Ground Pin Current (Note 7) MIN TYP MAX UNITS VIN = 3.8V, IOUT = 1mA, TJ = 25°C 4.3V < VIN < 20V, 1mA < IOUT < 700mA ● 3.250 3.200 3.300 3.300 3.350 3.400 V V VIN = 5.5V, IOUT = 1mA, TJ = 25°C 6V < VIN < 20V, 1mA < IOUT < 700mA ● 4.925 4.850 5.000 5.000 5.075 5.150 V V VIN = 4.3V, IOUT = 1mA, TJ = 25°C 4.8V < VIN < 20V, 1mA < IOUT < 700mA ● 3.695 3.640 3.750 3.750 3.805 3.860 V V ∆VIN = 4.8V to 20V, IOUT = 1mA ∆VIN = 5.5V to 20V, IOUT = 1mA ● 1.5 10 mV ● 1.5 10 mV ∆VIN = 4.3V to 20V, IOUT = 1mA ∆ILOAD = 1mA to 700mA, TJ = 25°C ∆ILOAD = 1mA to 700mA ● 1.5 10 mV ● 6 15 20 30 mV mV ∆ILOAD = 1mA to 700mA, TJ = 25°C ∆ILOAD = 1mA to 700mA ● 6 20 20 30 mV mV ∆ILOAD = 1mA to 700mA, TJ = 25°C ∆ILOAD = 1mA to 700mA ● 6 15 20 30 mV mV 0.13 0.20 0.25 V V 0.25 0.35 0.45 V V 0.37 0.45 0.60 V V 0.45 0.55 0.70 V V µA ILOAD = 10mA, TJ = 25°C ILOAD = 10mA ● ILOAD = 100mA, TJ = 25°C ILOAD = 100mA ● ILOAD = 500mA, TJ = 25°C ILOAD = 500mA ● ILOAD = 700mA, TJ = 25°C ILOAD = 700mA ● ILOAD = 0mA ● 50 70 ILOAD = 10mA ● 310 450 µA ILOAD = 100mA ● 2.0 3.5 mA ILOAD = 300mA ● 10 20 mA ILOAD = 500mA ● 25 45 mA ILOAD = 700mA ● 50 90 mA 150 300 nA 1.2 0.75 2.8 V V Adjust Pin Bias Current (Notes 5, 8) TJ = 25°C Shutdown Threshold VOUT = Off to On VOUT = On to Off ● ● Shutdown Pin Current (Note 9) VSHDN = 0V ● 6 10 µA Quiescent Current in Shutdown (Note 10) VIN = 6V, VSHDN = 0V ● 15 25 µA Ripple Rejection VIN – VOUT = 1V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 0.7A, TJ = 25°C Current Limit VIN – VOUT = 7V, TJ = 25°C Input Reverse Leakage Current VIN = –20V, VOUT = 0V Reverse Output Current (Note 11) LT1129-3.3 LT1129-5 LT1129 (Note 5) VOUT = 3.3V, VIN = 0V VOUT = 5V, VIN = 0V VOUT = 3.8V, VIN = 0V 0.25 52 64 1.2 ● 16 16 16 dB 1.6 A 1.0 mA 25 25 25 µA µA µA 112935fc 3 LT1129/LT1129-3.3/LT1129-5 ELECTRICAL CHARACTERISTICS Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The shutdown pin input voltage rating is required for a low impedance source. Internal protection devices connected to the shutdown pin will turn on and clamp the pin to approximately 7V or – 0.6V. This range allows the use of 5V logic devices to drive the pin directly. For high impedance sources or logic running on supply voltages greater than 5.5V, the maximum current driven into the shutdown pin must be limited to less than 20mA. Note 3: For junction temperatures greater than 110°C, a minimum load of 1mA is recommended. For TJ > 110°C and IOUT < 1mA, output voltage may increase by 1%. Note 4: Operating conditions are limited by maximum junction temperature. The regulated output voltage specification will not apply for all possible combinations of input voltage and output current. When operating at maximum input voltage, the output current range must be limited. When operating at maximum output current the input voltage range must be limited. Note 5: The LT1129 is tested and specified with the adjust pin connected to the output pin. Note 6: Dropout voltage is the minimum input/output voltage required to maintain regulation at the specified output current. In dropout the output voltage will be equal to (VIN – VDROPOUT). Dropout voltage is measured between the input pin and the output pin. External voltage drops between the output pin and the sense pin will add to the dropout voltage. Note 7: Ground pin current is tested with VIN = VOUT (nominal) and a current source load. This means that the device is tested while operating in its dropout region. This is the worst case ground pin current. The ground pin current will decrease slightly at higher input voltages. Note 8: Adjust pin bias current flows into the adjust pin. Note 9: Shutdown pin current at VSHDN = 0V flows out of the shutdown pin. Note 10: Quiescent current in shutdown is equal to the sum total of the shutdown pin current (6µA) and the ground pin current (9µA). Note 11: Reverse output current is tested with the input pin grounded. The output pin and the sense pin are forced to the rated output voltage. This current flows into the sense pin and out of the ground pin. For the LT1129 (adjustable version) the sense pin is internally tied to the output pin. Note 12: For C-grade devices Regulated Output Voltage, Line Regulation, and Load Regulation are guaranteed over the extended temperature range of – 40°C to 125°C. These parameters are not tested or quality assurance sampled at –40°C. They are guaranteed by design, correlation and/or inference from 25°C and/or 0°C tests. 112935fc 4 LT1129/LT1129-3.3/LT1129-5 U W TYPICAL PERFOR A CE CHARACTERISTICS 0.6 TJ ≤ 125°C 0.5 TJ ≤ 25°C 0.3 0.2 0.1 70 A. ILOAD = 700mA B. ILOAD = 500mA C. ILOAD = 300mA D. ILOAD = 100mA E. ILOAD = 10mA 0.5 60 A QUIESCENT CURRENT (µA) 0.6 0.4 Quiescent Current Dropout Voltage 0.7 DROPOUT VOLTAGE (V) DROPOUT VOLTAGE (V) Guaranteed Dropout Voltage 0.7 B C 0.4 D 0.3 E 0.2 VSHDN = OPEN (HI) 50 40 30 VSHDN = 0V 20 10 0.1 = TEST POINTS 0 0 0.3 0.4 0.2 0.5 OUTPUT CURRENT (A) 0.1 0.6 0 –50 0.7 50 25 0 75 TEMPERATURE (°C) –25 1129 G02 250 175 VSHDN = OPEN (HI) 125 100 75 50 VSHDN = 0V 25 200 175 150 VSHDN = OPEN (HI) 125 100 75 50 VSHDN = 0V 25 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 1 2 3 4 5 6 7 INPUT VOLTAGE (V) LT1129-3.3 Output Voltage 8 9 OUTPUT VOLTAGE (V) 3.300 3.275 3.250 3.225 50 100 125 1129 G06 VSHDN = 0V 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 9 10 1129 G13 3.850 ILOAD = 1mA 3.825 5.050 5.025 5.000 4.975 4.950 4.900 –50 8 LT1129 Adjust Pin Voltage 4.925 50 25 0 75 TEMPERATURE (°C) 75 0 ADJUST PIN VOLTAGE (V) 5.075 3.325 –25 100 10 5.100 ILOAD = 1mA 3.350 VSHDN = OPEN (HI) 125 LT1129-5 Output Voltage 3.400 3.200 –50 150 1129 G14 1129 G12 3.375 175 0 0 10 200 25 0 0 ILOAD = 0 RLOAD = ∞ VOUT = VADJ 225 QUIESCENT CURRENT (µA) 200 150 ILOAD = 0 RLOAD = ∞ 225 QUIESCENT CURRENT (µA) QUIESCENT CURRENT (µA) LT1129 Quiescent Current 250 ILOAD = 0 RLOAD = ∞ 125 100 1129 G11 LT1129-5 Quiescent Current 250 225 50 25 0 75 TEMPERATURE (°C) –25 1129 G10 LT1129-3.3 Quiescent Current ADJUST PIN VOLTAGE (V) 0 –50 125 100 ILOAD = 1mA 3.800 3.775 3.750 3.725 3.700 3.675 –25 50 25 0 75 TEMPERATURE (°C) 100 125 1129 G04 3.650 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 1129 G05 112935fc 5 LT1129/LT1129-3.3/LT1129-5 U W TYPICAL PERFOR A CE CHARACTERISTICS LT1129-3.3 Ground Pin Current LT1129-5 Ground Pin Current 2.0 2.0 1.8 RLOAD = 33Ω ILOAD = 100mA* GROUND PIN CURRENT (mA) 1.6 1.4 1.2 RLOAD = 66Ω ILOAD = 50mA* 1.0 0.8 0.6 RLOAD = 330Ω ILOAD = 10mA* 0.4 0.2 0 1 2 1.6 1.2 RLOAD = 100Ω ILOAD = 50mA* 1.0 0.8 0.6 RLOAD = 500Ω ILOAD = 10mA* 0.4 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1 0 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 1129 G18 20 0 RLOAD = 11Ω ILOAD = 300mA* 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 50 40 RLOAD = 7.1Ω ILOAD = 700mA* 30 RLOAD = 10Ω ILOAD = 500mA* 20 0 10 RLOAD = 16.6Ω ILOAD = 300mA* *For VOUT = 5V 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 TJ = 25°C 30 20 TJ = –50°C 10 0 0.1 0.2 0.3 0.4 0.5 OUTPUT CURRENT (A) 0.6 0.7 1129 G15 9 10 RLOAD = 7.5Ω ILOAD = 500mA* 20 10 RLOAD = 12.6Ω ILOAD = 300mA* *For VOUT = 3.75V 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1129 G23 Shutdown Pin Threshold (Off-to-On) 2.0 ILOAD = 1mA 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0 –50 1.6 ILOAD = 700mA 1.4 1.2 ILOAD = 1mA 1.0 0.8 0.6 0.4 0.2 0.2 0 30 0 9 SHUTDOWN THRESHOLD (V) SHUTDOWN THRESHOLD (V) GROUND PIN CURRENT (mA) 1.8 TJ = 125°C 8 RLOAD = 5.3Ω ILOAD = 700mA* 40 10 2.0 40 3 4 5 6 7 INPUT VOLTAGE (V) TJ = 25°C VOUT = VADJ 50 Shutdown Pin Threshold (On-to-Off) 70 50 2 1129 G22 Ground Pin Current 60 *For VOUT = 3.75V 1 60 1129 G21 VIN = 3.3V (LT1129-3.3) VIN = 5V (LT1129-5) VIN = 3.75V (LT1129) DEVICE IS OPERATING IN DROPOUT RLOAD = 375Ω ILOAD = 10mA* 0.4 LT1129 Ground Pin Current TJ = 25°C VOUT = VSENSE 10 *For VOUT = 3.3V 0 0.6 1129 G20 GROUND PIN CURRENT (mA) RLOAD = 6.6Ω ILOAD = 500mA* GROUND PIN CURRENT (mA) GROUND PIN CURRENT (mA) 30 10 0.8 0 60 TJ = 25°C VOUT = VSENSE RLOAD = 4.7Ω ILOAD = 700mA* RLOAD = 75Ω ILOAD = 50mA* 1.0 LT1129-5 Ground Pin Current 60 40 1.2 0 10 RLOAD = 38Ω ILOAD = 100mA* 1.4 1129 G19 LT1129-3.3 Ground Pin Current 50 1.6 0.2 *For VOUT = 5V 0 TJ = 25°C VOUT = VADJ 1.8 RLOAD = 50Ω ILOAD = 100mA* 1.4 0.2 *For VOUT = 3.3V 0 2.0 TJ = 25°C VOUT = VSENSE GROUND PIN CURRENT (mA) TJ = 25°C VOUT = VSENSE 1.8 GROUND PIN CURRENT (mA) LT1129 Ground Pin Current –25 50 25 0 75 TEMPERATURE (°C) 100 125 1129 G27 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 1129 G26 112935fc 6 LT1129/LT1129-3.3/LT1129-5 U W TYPICAL PERFOR A CE CHARACTERISTICS Shutdown Pin Input Current Shutdown Pin Current 10 8 7 6 5 4 3 2 1 0 –50 50 25 0 75 TEMPERATURE (°C) –25 100 ADJUST PIN BIAS CURRENT (nA) SHUTDOWN PIN CURRENT (µA) SHUTDOWN PIN INPUT CURRENT (mA) VSHDN = 0V 9 Adjust Pin Bias Current 400 25 20 15 10 5 0 1 7 3 8 2 5 6 4 SHUTDOWN PIN VOLTAGE (V) 1129 G25 Reverse Output Current VIN = 0V VOUT = VSENSE = 5V (LT1129-5) VOUT = VSENSE = 3.3V (LT1129-3.3) VOUT = VADJ = 3.75V (LT1129) 1.0 0.8 0.6 0.4 125 0 1 4 3 2 5 INPUT VOLTAGE (V) 0.4 LT1129-3.3 –25 (VIN – VOUT)AVG = 1V VRIPPLE = 0.5VP-P IL = 0.7A IOUT = 500mA VIN = 6V + 50mVRMS RIPPLE 90 80 66 64 62 60 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE (V) 58 9 10 1129 G30 56 –50 125 Ripple Rejection 70 COUT = 47µF SOLID TANTALUM 60 50 40 30 COUT = 3.3µF SOLID TANTALUM 20 10 100 100 20 LT1129-5 50 25 0 75 TEMPERATURE (°C) 1129 G08 RIPPLE REJECTION (dB) RIPPLE REJECTION (dB) 68 LT1129 VIN = 7V VOUT = 0V 0 –50 7 6 70 40 0 0.6 Ripple Rejection TJ = 25°C, VIN = 0V VOUT = VSENSE (LT1129-3.3/LT1129-5) VOUT = VADJ (LT1129) CURRENT FLOWS INTO DEVICE 30 125 0.8 1129 G07 100 50 100 1.0 0.2 0 100 Reverse Output Current 60 50 25 0 75 TEMPERATURE (°C) 1.2 1129 G29 70 –25 Current Limit 0.2 80 50 1.4 SHORT-CIRCUIT CURRENT (A) SHORT-CIRCUIT CURRENT (A) OUTPUT CURRENT (µA) 10 90 100 VOUT = 0V 15 50 25 0 75 TEMPERATURE (°C) 150 1129 G28 1.2 20 –25 200 Current Limit 5 OUTPUT CURRENT (µA) 9 1.4 0 –50 250 1129 G24 30 25 300 0 –50 0 125 VADJ = VOUT = 3.75V 350 10 0 –25 50 25 0 75 TEMPERATURE (°C) 100 125 1129 G03 10 100 1k 10k FREQUENCY (Hz) 100k 1M 1129 G01 112935fc 7 LT1129/LT1129-3.3/LT1129-5 U W TYPICAL PERFOR A CE CHARACTERISTICS LT1129-5 Transient Response Load Regulation LT1129-5 Transient Response 0 LT1129-5 –15 0.05 0 –0.05 –0.10 0.2 0.1 VIN = 6V CIN = 3.3µF COUT = 47µF 0 –0.1 –0.2 0.7 –25 –30 –50 VIN = VOUT(NOMINAL) + 1V ∆ILOAD = 1mA to 700mA *VADJ = VOUT 50 25 0 75 TEMPERATURE (°C) –25 100 125 0.6 0.5 0 50 100 150 200 250 300 350 400 450 500 TIME (µs) 1129 G09 1129 G31 LOAD CURRENT (A) –20 LOAD CURRENT (A) LOAD REGULATION (mV) LT1129* –10 VIN = 6V CIN = 3.3µF COUT = 3.3µF 0.10 OUTPUT VOLTAGE DEVIATION (V) OUTPUT VOLTAGE DEVIATION (V) LT1129-3.3 –5 0.5 0.3 0.1 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 TIME (ms) 1129 G32 U U U PI FU CTIO S Input Pin: Power is supplied to the device through the input pin. The input pin should be bypassed to ground if the device is more than 6 inches away from the main input filter capacitor. In general, the output impedance of a battery rises with frequency so it is advisable to include a bypass capacitor in battery-powered circuits. A bypass capacitor in the range of 1µF to 10µF is sufficient. The LT1129 is designed to withstand reverse voltages on the input pin with respect to both ground and the output pin. In the case of a reversed input, which can happen if a battery is plugged in backwards, the LT1129 will act as if there is a diode in series with its input. There will be no reverse current flow into the LT1129 and no reverse voltage will appear at the load. The device will protect both itself and the load. Output Pin: The output pin supplies power to the load. An output capacitor is required to prevent oscillations. See the Applications Information section for recommended value of output capacitance and information on reverse output characteristics. Shutdown Pin (SHDN): This pin is used to put the device into shutdown. In shutdown the output of the device is turned off. This pin is active low. The device will be shut down if the shutdown pin is actively pulled low. The shutdown pin current with the pin pulled to ground will be 6µA. The shutdown pin is internally clamped to 7V and – 0.6V (one VBE). This allows the shutdown pin to be driven directly by 5V logic or by open collector logic with a pullup resistor. The pull-up resistor is only required to supply the leakage current of the open collector gate, normally several microamperes. Pull-up current must be limited to a maximum of 20mA. A curve of shutdown pin input current as a function of voltage appears in the Typical Performance Characteristics. If the shutdown pin is not used it can be left open circuit. The device will be active, output on, if the shutdown pin is not connected. Sense Pin: For fixed voltage versions of the LT1129 (LT1129-3.3, LT1129-5) the sense pin is the input to the error amplifier. Optimum regulation will be obtained at the point where the sense pin is connected to the output pin. For most applications the sense pin is connected directly to the output pin at the regulator. In critical applications small voltage drops caused by the resistance (RP) of PC traces between the regulator and the load, which would normally degrade regulation, may be eliminated by connecting the sense pin to the output pin at the load as shown in Figure 1 (Kelvin Sense Connection). Note that the voltage drop across the external PC traces will add to the dropout voltage of the regulator. The sense pin bias current is 15µA at the nominal regulated output voltage. This pin is internally clamped to – 0.6V (one VBE). 112935fc 8 LT1129/LT1129-3.3/LT1129-5 U U U PI FU CTIO S Adjust Pin: For the LT1129 (adjustable version) the adjust pin is the input to the error amplifier. This pin is internally clamped to 6V and – 0.6V (one VBE). This pin has a bias current of 150nA which flows into the pin. See Bias Current curve in the Typical Performance Characteristics. The adjust pin reference voltage is equal to 3.75V referenced to ground. RP IN OUT LT1129 1µF SHDN SENSE LOAD + 10µF GND RP LT1129 • F01 Figure 1. Kelvin Sense Connection U W U U APPLICATIO S I FOR ATIO The LT1129 is a micropower low dropout regulator with shutdown, capable of supplying 700mA of output current at a dropout voltage of 0.4V. The device operates with very low quiescent current (50µA). In shutdown the quiescent current drops to only 16µA. In addition to the low quiescent current the LT1129 incorporates several protection features which make it ideal for use in battery-powered systems. The device is protected against reverse input voltages. In battery backup applications where the output can be held up by a backup battery when the input is pulled to ground, the LT1129 acts like it has a diode in series with its output and prevents reverse current flow. Adjustable Operation The adjustable version of the LT1129 has an output voltage range of 3.75V to 30V. The output voltage is set by the ratio of two external resistors as shown in Figure 2. The device servos the output voltage to maintain the voltage at the adjust pin at 3.75V. The current in R1 is then equal to 3.75V/R1. The current in R2 is equal to the sum of the current in R1 and the adjust pin bias current. The adjust pin bias current, 150nA at 25°C, flows through R2 into the adjust pin. The output voltage can be calculated according to the formula in Figure 2. The value of R1 should be less than 400k to minimize errors in the output voltage caused by the adjust pin bias current. Note that in shutdown the output is turned off and the divider current will be zero. Curves of Adjust Pin Voltage vs Temperature and Adjust Pin Bias Current vs Temperature appear in the Typical Performance Characteristics. The reference voltage at the adjust pin has a positive temperature coefficient of approximately 15ppm/°C. The adjust pin bias current has a negative temperature coefficient. These effects are small and will tend to cancel each other. The adjustable device is specified with the adjust pin tied to the output pin. This sets the output voltage to 3.75V. Specifications for output voltages greater than 3.75V will be proportional to the ratio of the desired output voltage to 3.75V (VOUT/3.75V). For example: load regulation for an output current change of 1mA to 700mA is – 6mV typical at VOUT = 3.75V. At VOUT = 12V, load regulation would be: ⎛ 12V ⎞ ⎜ ⎟ • ( – 6mV ) = ( –19mV ) ⎝ 3.75V ⎠ IN VOUT OUT LT1129 SHDN R2 ADJ + R1 GND LT1129 • F02 VOUT = 3.75V 1 + R2 + IADJ • R2 R1 VADJ = 3.75V IADJ = 150nA at 25°C OUTPUT RANGE = 3.75V to 30V ( ) ( ) Figure 2. Adjustable Operation 112935fc 9 LT1129/LT1129-3.3/LT1129-5 U W U U APPLICATIO S I FOR ATIO Thermal Considerations The power handling capability of the device will be limited by the maximum rated junction temperature (125°C). The power dissipated by the device will be made up of two components: copper. This data can be used as a rough guideline in estimating thermal resistance. The thermal resistance for each application will be affected by thermal interactions with other components as well as board size and shape. Some experimentation will be necessary to determine the actual value. 1. Output current multiplied by the input/output voltage differential: IOUT • (VIN – VOUT), and Table 1. Q Package, 5-Lead DD 2. Ground pin current multiplied by the input voltage: IGND • VIN. TOPSIDE* The ground pin current can be found by examining the Ground Pin Current curves in the Typical Performance Characteristics. Power dissipation will be equal to the sum of the two components listed above. The LT1129 series regulators have internal thermal limiting designed to protect the device during overload conditions. For continuous normal load conditions the maximum junction temperature rating of 125°C must not be exceeded. It is important to give careful consideration to all sources of thermal resistance from junction to ambient. Additional heat sources mounted nearby must also be considered. For surface mount devices heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper traces. Experiments have shown that the heat spreading copper layer does not need to be electrically connected to the tab of the device. The PC material can be very effective at transmitting heat between the pad area, attached to the tab of the device, and a ground or power plane layer either inside or on the opposite side of the board. Although the actual thermal resistance of the PC material is high, the length/area ratio of the thermal resistor between layers is small. Copper board stiffeners and plated through holes can also be used to spread the heat generated by power devices. COPPER AREA BACKSIDE THERMAL RESISTANCE BOARD AREA (JUNCTION-TO-AMBIENT) 2500 sq. mm 2500 sq. mm 2500 sq. mm 1000 sq. mm 2500 sq. mm 2500 sq. mm 27°C/W 125 sq. mm 2500 sq. mm 35°C/W 2500 sq. mm 25°C/W * Tab of device attached to topside copper Table 2. ST Package, 3-Lead SOT-223 COPPER AREA TOPSIDE* BACKSIDE THERMAL RESISTANCE BOARD AREA (JUNCTION-TO-AMBIENT) 2500 sq. mm 2500 sq. mm 2500 sq. mm 45°C/W 1000 sq. mm 2500 sq. mm 2500 sq. mm 45°C/W 225 sq. mm 2500 sq. mm 2500 sq. mm 53°C/W 100 sq. mm 2500 sq. mm 2500 sq. mm 59°C/W * Tab of device attached to topside copper Table 3. S8 Package, 8-Lead Plastic SOIC COPPER AREA TOPSIDE* BACKSIDE THERMAL RESISTANCE BOARD AREA (JUNCTION-TO-AMBIENT) 2500 sq. mm 2500 sq. mm 2500 sq. mm 55°C/W 1000 sq. mm 2500 sq. mm 2500 sq. mm 55°C/W 225 sq. mm 2500 sq. mm 2500 sq. mm 63°C/W 100 sq. mm 2500 sq. mm 2500 sq. mm 69°C/W * Device attached to topside copper T Package, 5-Lead TO-220 Thermal Resistance (Junction-to-Case) = 5°C/W The following tables list thermal resistances for each package. For the TO-220 package, thermal resistance is given for junction-to-case only since this package is usually mounted to a heat sink. Measured values of thermal resistance for several different board sizes and copper areas are listed for each package. All measurements were taken in still air on 3/32" FR-4 board with 1-oz 112935fc 10 LT1129/LT1129-3.3/LT1129-5 U W U U APPLICATIO S I FOR ATIO Calculating Junction Temperature Protection Features Example: Given an output voltage of 3.3V, an input voltage range of 4.5V to 5.5V, an output current range of 0mA to 500mA, and a maximum ambient temperature of 50°C, what will the maximum junction temperature be? The LT1129 incorporates several protection features which make it ideal for use in battery-powered circuits. In addition to the normal protection features associated with monolithic regulators, such as current limiting and thermal limiting, the device is protected against reverse input voltages, and reverse voltages from output to input. For fixed voltage devices the output and sense pins are tied together at the output. The power dissipated by the device will be equal to: IOUT MAX • (VIN MAX – VOUT) + (IGND • VIN MAX) where, IOUT MAX = 500mA VIN MAX = 5.5V IGND at (IOUT = 500mA, VIN = 5.5V) = 25mA so, P = 500mA • (5.5V – 3.3V) + (25mA • 5.5V) = 1.24W If we use a DD package, then the thermal resistance will be in the range of 25°C/W to 35°C/W depending on copper area. So the junction temperature rise above ambient will be approximately equal to: 1.24W • 30°C/W = 37.2°C The maximum junction temperature will then be equal to the maximum junction temperature rise above ambient plus the maximum ambient temperature or: TJMAX = 50°C + 37.2°C = 87.2°C Output Capacitance and Transient Performance The LT1129 is designed to be stable with a wide range of output capacitors. The minimum recommended value is 3.3µF with an ESR of 2Ω or less. The LT1129 is a micropower device and output transient response will be a function of output capacitance. See the Transient Response curves in the Typical Performance Characteristics. Larger values of output capacitance will decrease the peak deviations and provide improved output transient response. Bypass capacitors, used to decouple individual components powered by the LT1129, will increase the effective value of the output capacitor. Current limit protection and thermal overload protection are intended to protect the device against current overload conditions at the output of the device. For normal operation, the junction temperature should not exceed 125°C. The input of the device will withstand reverse voltages of 30V. Current flow into the device will be limited to less than 1mA (typically less than 100µA) and no negative voltage will appear at the output. The device will protect both itself and the load. This provides protection against batteries that can be plugged in backwards. For fixed voltage versions of the device, the sense pin is internally clamped to one diode drop below ground. For the adjustable version of the device, the output pin is internally clamped at one diode drop below ground. If the output pin of an adjustable device, or the sense pin of a fixed voltage device, is pulled below ground, with the input open or grounded, current must be limited to less than 5mA. In circuits where a backup battery is required, several different input/output conditions can occur. The output voltage may be held up while the input is either pulled to ground, pulled to some intermediate voltage, or is left open circuit. Current flow back into the output will vary depending on the conditions. Many battery-powered circuits incorporate some form of power management. The following information will help optimize battery life. Table 3 summarizes the following information. The reverse output current will follow the curve in Figure 3 when the input pin is pulled to ground. This current flows through the output pin to ground. The state of the shutdown pin will have no effect on output current when the input pin is pulled to ground. 112935fc 11 LT1129/LT1129-3.3/LT1129-5 U U W U APPLICATIO S I FOR ATIO In some applications it may be necessary to leave the input to the LT1129 unconnected when the output is held high. This can happen when the LT1129 is powered from a rectified AC source. If the AC source is removed, then the input of the LT1129 is effectively left floating. The reverse output current also follows the curve in Figure 3 if the input pin is left open. The state of the shutdown pin will have no effect on the reverse output current when the input pin is floating. When the input of the LT1129 is forced to a voltage below its nominal output voltage and its output is held high, the reverse output current will still follow the curve shown in Figure 3. This can happen if the input of the LT1129 is connected to a discharged (low voltage) battery and the output is held up by either a backup battery or by a second regulator circuit. When the input pin is forced below the output pin or the output pin is pulled above the input pin, the input current will typically drop to less than 2µA (see Figure 4). The state of the shutdown pin will have no effect on the reverse output current when the output is pulled above the input. 5 TJ = 25°C 90 VIN = 0V VSENSE = VOUT 80 CURRENT FLOWS 70 INTO DEVICE 60 LT1129 50 40 LT1129-3.3 30 3 2 1 20 LT1129-5 10 0 VOUT = 3.3V (LT1129-3.3) VOUT = 5V (LT1129-5) 4 INPUT CURRENT (µA) OUTPUT PIN CURRENT (µA) 100 0 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE (V) 9 10 0 1 3 2 INPUT VOLTAGE (V) 4 1129 F03 Figure 3. Reverse Output Current 5 1129 F04 Figure 4. Input Current Table 4. Fault Conditions INPUT PIN SHDN PIN OUTPUT PIN < VOUT (Nominal) Open (Hi) Forced to VOUT (Nominal) Reverse Output Current ≈ 15µA (See Figure 3) Input Current ≈ 1µA (See Figure 4) < VOUT (Nominal) Grounded Forced to VOUT (Nominal) Reverse Output Current ≈ 15µA (See Figure 3) Input Current ≈ 1µA (See Figure 4) Open Open (Hi) Forced to VOUT (Nominal) Reverse Output Current ≈ 15µA (See Figure 3) Open Grounded Forced to VOUT (Nominal) Reverse Output Current ≈ 15µA (See Figure 3) 112935fc 12 LT1129/LT1129-3.3/LT1129-5 U PACKAGE DESCRIPTIO F Package 20-Lead Plastic TSSOP (4.4mm) (LTC DWG # 05-08-1650) 6.40 – 6.60* (.252 – .260) 1.05 ±0.10 6.60 ±0.10 20 19 18 17 16 15 14 13 12 11 4.50 ±0.10 0.45 ±0.05 6.40 (.252) BSC 0.65 BSC 1 2 3 4 5 6 7 8 9 10 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50** (.169 – .177) 0.09 – 0.20 (.0035 – .0079) 0.25 REF 1.10 (.0433) MAX 0° – 8° 0.65 (.0256) BSC 0.50 – 0.75 (.020 – .030) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) 0.19 – 0.30 (.0075 – .0118) TYP 0.05 – 0.15 (.002 – .006) F20 TSSOP 0204 3. DRAWING NOT TO SCALE *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED .152mm (.006") PER SIDE OBSOLETE PACKAGE 112935fc 13 LT1129/LT1129-3.3/LT1129-5 U PACKAGE DESCRIPTIO Q Package 5-Lead Plastic DD Pak (LTC DWG # 05-08-1461) .256 (6.502) .060 (1.524) TYP .060 (1.524) .390 – .415 (9.906 – 10.541) .165 – .180 (4.191 – 4.572) .045 – .055 (1.143 – 1.397) 15° TYP .060 (1.524) .183 (4.648) +.008 .004 –.004 +0.203 0.102 –0.102 .059 (1.499) TYP .330 – .370 (8.382 – 9.398) ( ) .095 – .115 (2.413 – 2.921) .075 (1.905) .300 (7.620) +.012 .143 –.020 +0.305 3.632 –0.508 ( BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK .067 (1.702) .028 – .038 BSC (0.711 – 0.965) TYP ) Q(DD5) 0502 .420 .276 .080 .420 .050 ± .012 (1.270 ± 0.305) .013 – .023 (0.330 – 0.584) .325 .350 .205 .565 .565 .320 .090 .090 .067 .042 RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS IN INCH/(MILLIMETER) 2. DRAWING NOT TO SCALE .067 .042 RECOMMENDED SOLDER PAD LAYOUT FOR THICKER SOLDER PASTE APPLICATIONS 112935fc 14 LT1129/LT1129-3.3/LT1129-5 U PACKAGE DESCRIPTIO S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 .245 MIN .160 ±.005 7 5 6 .053 – .069 (1.346 – 1.752) .150 – .157 (3.810 – 3.988) NOTE 3 .228 – .244 (5.791 – 6.197) .030 ±.005 TYP 1 2 3 INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE .050 (1.270) BSC .014 – .019 (0.355 – 0.483) TYP .010 – .020 × 45° (0.254 – 0.508) 4 RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS IN .004 – .010 (0.101 – 0.254) .008 – .010 (0.203 – 0.254) 0°– 8° TYP 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) .016 – .050 (0.406 – 1.270) SO8 0303 ST Package 3-Lead Plastic SOT-223 (LTC DWG # 05-08-1630) .248 – .264 (6.30 – 6.71) .129 MAX .114 – .124 (2.90 – 3.15) .059 MAX .264 – .287 (6.70 – 7.30) .248 BSC .130 – .146 (3.30 – 3.71) .039 MAX .059 MAX .181 MAX .033 – .041 (0.84 – 1.04) .0905 (2.30) BSC .090 BSC RECOMMENDED SOLDER PAD LAYOUT 10° – 16° .010 – .014 (0.25 – 0.36) 10° MAX .071 (1.80) MAX 10° – 16° .024 – .033 (0.60 – 0.84) .181 (4.60) BSC .012 (0.31) MIN .0008 – .0040 (0.0203 – 0.1016) ST3 (SOT-233) 0502 112935fc 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. 15 LT1129/LT1129-3.3/LT1129-5 U TYPICAL APPLICATIO T Package 5-Lead Plastic TO-220 (Standard) (LTC DWG # 05-08-1421) .165 – .180 (4.191 – 4.572) .147 – .155 (3.734 – 3.937) DIA .390 – .415 (9.906 – 10.541) .045 – .055 (1.143 – 1.397) .230 – .270 (5.842 – 6.858) .570 – .620 (14.478 – 15.748) .460 – .500 (11.684 – 12.700) .620 (15.75) TYP .330 – .370 (8.382 – 9.398) .700 – .728 (17.78 – 18.491) SEATING PLANE .152 – .202 .260 – .320 (3.861 – 5.131) (6.60 – 8.13) .095 – .115 (2.413 – 2.921) .155 – .195* (3.937 – 4.953) .013 – .023 (0.330 – 0.584) BSC .067 (1.70) .028 – .038 (0.711 – 0.965) .135 – .165 (3.429 – 4.191) * MEASURED AT THE SEATING PLANE T5 (TO-220) 0801 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1121 150mA LDO Micropower Regulator 30µA IQ, SOT-223 Package LT1761 100mA Low Noise, LDO Micropower Regulator 20µA IQ, 20µVRMS Noise LT1762 150mA Low Noise, LDO Micropower Regulator 25µA IQ, 20µVRMS Noise LT1962 300mA Low Noise, LDO Micropower Regulator 30µA IQ, 20µVRMS Noise LT1763 500mA Low Noise, LDO Micropower Regulator 30µA IQ, 20µVRMS Noise LT1963 1.5A Low Noise, Fast Transient, LDO Regulator 340mV Dropout Voltage, 40µVRMS Noise LT1764 3A Low Noise, Fast Transient, LDO Regulator 340mV Dropout Voltage, 40µVRMS Noise 112935fc 16 Linear Technology Corporation LT/TP 0205 1K REV C • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 1994