LT1764 Series 3A, Fast Transient Response, Low Noise, LDO Regulators U FEATURES DESCRIPTIO ■ The LT ®1764 is a low dropout regulator optimized for fast transient response. The device is capable of supplying 3A of output current with a dropout voltage of 340mV. Operating quiescent current is 1mA, dropping to < 1µA in shutdown. Quiescent current is well controlled; it does not rise in dropout as it does with many other regulators. In addition to fast transient response, the LT1764 has very low output voltage noise which makes the device ideal for sensitive RF supply applications. Output voltage range is from 1.21V to 20V. The LT1764 regulators are stable with output capacitors as low as 10µF. Internal protection circuitry includes reverse battery protection, current limiting, thermal limiting and reverse current protection. The device is available in fixed output voltages of 1.5V, 1.8V, 2.5V, 3.3V and as an adjustable device with a 1.21V reference voltage. The LT1764 regulators are available in 5-lead TO-220, DD and Exposed Pad 16-lead TSSOP packages. ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Optimized for Fast Transient Response Output Current: 3A Dropout Voltage: 340mV at 3A Low Noise: 40µVRMS (10Hz to 100kHz) 1mA Quiescent Current Wide Input Voltage Range: 2.7V to 20V No Protection Diodes Needed Controlled Quiescent Current in Dropout Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3.3V Adjustable Output from 1.21V to 20V < 1µA Quiescent Current in Shutdown Stable with 10µF Output Capacitor Reverse Battery Protection No Reverse Current Thermal Limiting Available in 5-Lead TO-220, DD and 16-Lead TSSOP Packages U APPLICATIO S ■ , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6144250, 6118263. 3.3V to 2.5V Logic Power Supply Post Regulator for Switching Supplies U ■ TYPICAL APPLICATIO Dropout Voltage 400 3.3VIN to 2.5VOUT Regulator VIN > 3V OUT 2.5V 3A + 10µF 10µF LT1764-2.5 SHDN SENSE GND DROPOUT VOLTAGE (mV) IN + 350 300 250 200 150 100 1764 TA01 50 0 0 0.5 1.0 1.5 2.0 LOAD CURRENT (A) 2.5 3.0 1764 TA02 1764fb 1 LT1764 Series U W W W ABSOLUTE MAXIMUM RATINGS (Note 1) IN Pin Voltage ........................................................ ±20V OUT Pin Voltage .................................................... ±20V Input to Output Differential Voltage (Note 12) ....... ±20V SENSE Pin Voltage ............................................... ±20V ADJ Pin Voltage ...................................................... ±7V SHDN Pin Voltage ................................................. ±20V Output Short-Circuit Duration ......................... Indefinite Operating Junction Temperature Range – 40°C to 125°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C W U U PACKAGE/ORDER INFORMATION TOP VIEW FRONT VIEW FRONT VIEW TAB IS GND 5 SENSE/ADJ* 5 SENSE/ ADJ* 4 OUT 4 OUT 3 GND 3 GND 2 IN 2 IN 1 SHDN 1 SHDN Q PACKAGE 5-LEAD PLASTIC DD *PIN 5 = SENSE FOR LT1764-1.5/LT1764-1.8/ LT1764-2.5/LT1764-3.3 = ADJ FOR LT1764 TJMAX = 150°C, θJA = 30°C/ W T PACKAGE 5-LEAD PLASTIC TO-220 TAB IS GND *PIN 5 = SENSE FOR LT1764-1.5/LT1764-1.8/ LT1764-2.5/LT1764-3.3 = ADJ FOR LT1764 TJMAX = 150°C, θJA = 50°C/ W GND 1 16 GND NC 2 15 NC OUT 3 14 IN OUT 4 OUT 5 12 IN SENSE/ADJ* 6 11 NC GND 7 10 SHDN GND 8 9 17 13 IN GND FE PACKAGE 16-LEAD PLASTIC TSSOP EXPOSED PAD (PIN 17) IS GND. MUST BE SOLDERED TO THE PCB. *PIN 6 = SENSE FOR LT1764-1.5/ LT1764-1.8/LT1764-2.5/ LT1764-3.3 = ADJ FOR LT1764 TJMAX = 150°C, θJA = 38°C/ W ORDER PART NUMBER ORDER PART NUMBER ORDER PART NUMBER FE PART MARKING LT1764EQ LT1764EQ-1.5 LT1764EQ-1.8 LT1764EQ-2.5 LT1764EQ-3.3 LT1764ET LT1764ET-1.5 LT1764ET-1.8 LT1764ET-2.5 LT1764ET-3.3 LT1764EFE LT1764EFE-1.5 LT1764EFE-1.8 LT1764EFE-2.5 LT1764EFE-3.3 1764EFE 1764EFE15 1764EFE18 1764EFE25 1764EFE33 Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges. 1764fb 2 LT1764 Series ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) PARAMETER CONDITIONS Minimum Input Voltage (Notes 3, 11) ILOAD = 0.5A ILOAD = 1.5A ILOAD = 2.7A, 110°C < TJ ≤ 125°C ILOAD = 3A, – 40°C ≤ TJ ≤ 110°C Regulated Output Voltage (Note 4) MIN TYP MAX UNITS 1.7 1.9 2.3 2.3 2.7 2.7 V V V V LT1764-1.5 VIN = 2.21V, ILOAD = 1mA 2.7V < VIN < 20V, 1mA < ILOAD < 3A, – 40°C ≤ TJ ≤ 110°C 2.7V < VIN < 20V, 1mA < ILOAD < 2.7A, 110°C < TJ ≤ 125°C 1.477 1.447 1.447 1.500 1.500 1.500 1.523 1.545 1.545 V V V LT1764-1.8 VIN = 2.3V, ILOAD = 1mA 2.8V < VIN < 20V, 1mA < ILOAD < 3A, – 40°C ≤ TJ ≤ 110°C 2.8V < VIN < 20V, 1mA < ILOAD < 2.7A, 110°C < TJ ≤ 125°C 1.773 1.737 1.737 1.800 1.800 1.800 1.827 1.854 1.854 V V V LT1764-2.5 VIN = 3V, ILOAD = 1mA 3.5V < VIN < 20V, 1mA < ILOAD < 3A, – 40°C ≤ TJ ≤ 110°C 3.5V < VIN < 20V, 1mA < ILOAD < 2.7A, 110°C < TJ ≤ 125°C 2.462 2.412 2.412 2.500 2.500 2.500 2.538 2.575 2.575 V V V LT1764-3.3 VIN = 3.8V, ILOAD = 1mA 4.3V < VIN < 20V, 1mA < ILOAD < 3A, – 40°C ≤ TJ ≤ 110°C 4.3V < VIN < 20V, 1mA < ILOAD < 2.7A, 110°C < TJ ≤ 125°C 3.250 3.183 3.183 3.300 3.300 3.300 3.350 3.400 3.400 V V V ADJ Pin Voltage (Notes 3, 4) LT1764 1.192 1.168 1.168 1.210 1.210 1.210 1.228 1.246 1.246 V V V Line Regulation LT1764-1.5 LT1764-1.8 LT1764-2.5 LT1764-3.3 LT1764 (Note 3) ∆VIN = 2.21V to 20V, ILOAD = 1mA ∆VIN = 2.3V to 20V, ILOAD = 1mA ∆VIN = 3V to 20V, ILOAD = 1mA ∆VIN = 3.8V to 20V, ILOAD = 1mA ∆VIN = 2.21V to 20V, ILOAD = 1mA 2.5 3 4 4.5 2 10 10 10 10 10 mV mV mV mV mV Load Regulation LT1764-1.5 VIN = 2.7V, ∆ILOAD = 1mA to 3A VIN = 2.7V, ∆ILOAD = 1mA to 3A, – 40°C ≤ TJ ≤ 110°C VIN = 2.7V, ∆ILOAD = 1mA to 2.7A, 110°C < TJ ≤ 125°C 3 7 23 23 mV mV mV LT1764-1.8 VIN = 2.8V, ∆ILOAD = 1mA to 3A VIN = 2.8V, ∆ILOAD = 1mA to 3A, – 40°C ≤ TJ ≤ 110°C VIN = 2.8V, ∆ILOAD = 1mA to 2.7A, 110°C < TJ ≤ 125°C 4 8 25 25 mV mV mV LT1764-2.5 VIN = 3.5V, ∆ILOAD = 1mA to 3A VIN = 3.5V, ∆ILOAD = 1mA to 3A, – 40°C ≤ TJ ≤ 110°C VIN = 3.5V, ∆ILOAD = 1mA to 2.7A, 110°C < TJ ≤ 125°C 4 10 30 30 mV mV mV LT1764-3.3 VIN = 4.3V, ∆ILOAD = 1mA to 3A VIN = 4.3V, ∆ILOAD = 1mA to 3A, – 40°C ≤ TJ ≤ 110°C VIN = 4.3V, ∆ILOAD = 1mA to 2.7A, 110°C < TJ ≤ 125°C 4 12 40 40 mV mV mV LT1764 (Note 3) VIN = 2.7V, ∆ILOAD = 1mA to 3A VIN = 2.7V, ∆ILOAD = 1mA to 3A, – 40°C ≤ TJ ≤ 110°C VIN = 2.7V, ∆ILOAD = 1mA to 2.7A, 110°C < TJ ≤ 125°C 2 5 20 20 mV mV mV 0.02 0.05 0.10 V V 0.07 0.13 0.18 V V 0.14 0.20 0.27 V V 0.25 0.33 0.40 V V 0.66 V 0.34 0.45 0.66 V V VIN = 2.21V, ILOAD = 1mA 2.7V < VIN < 20V, 1mA < ILOAD < 3A, – 40°C ≤ TJ ≤ 110°C 2.7V < VIN < 20V, 1mA < ILOAD < 2.7A, 110°C < TJ ≤ 125°C ● ● ● ● ● Dropout Voltage VIN = VOUT(NOMINAL) ILOAD = 1mA ILOAD = 1mA ● (Notes 5, 6, 11) ILOAD = 100mA ILOAD = 100mA ● ILOAD = 500mA ILOAD = 500mA ● ILOAD = 1.5A ILOAD = 1.5A ● ILOAD = 2.7A, 110°C < TJ ≤ 125°C ILOAD = 3A ILOAD = 3A, – 40°C ≤ TJ ≤ 110°C 1764fb 3 LT1764 Series ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) PARAMETER CONDITIONS MIN GND Pin Current VIN = VOUT(NOMINAL) + 1V (Notes 5, 7) ILOAD = 0mA ILOAD = 1mA ILOAD = 100mA ILOAD = 500mA ILOAD = 1.5A ILOAD = 2.7A, 110°C < TJ ≤ 125°C ILOAD = 3A, – 40°C ≤ TJ ≤ 110°C Output Voltage Noise COUT = 10µF, ILOAD = 3A, BW = 10Hz to 100kHz ADJ Pin Bias Current (Notes 3, 8) Shutdown Threshold VOUT = Off to On VOUT = On to Off ● ● ● ● ● TYP MAX UNITS 1 1.1 3.5 11 40 120 120 1.5 1.6 5 18 75 200 200 mA mA mA mA mA mA mA µVRMS 40 ● ● 0.25 3 10 µA 0.9 0.75 2 V V SHDN Pin Current (Note 9) VSHDN = 0V VSHDN = 20V 0.01 7 1 30 µA µA Quiescent Current in Shutdown VIN = 6V, VSHDN = 0V 0.01 1 µA Ripple Rejection VIN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 1.5A Current Limit VIN = 7V, VOUT = 0V Input Reverse Leakage Current 55 63 dB 4 A LT1764-1.8, LT1764-2.5, LT1764-3.3 VIN = VOUT(NOMINAL) + 1V, ∆VOUT = – 0.1V, – 40°C ≤ TJ ≤ 110°C VIN = VOUT(NOMINAL) + 1V, ∆VOUT = – 0.1V, 110°C < TJ ≤ 125°C 3.1 2.8 A A LT1764, LT1764-1.5 VIN = 2.7V, ∆VOUT = – 0.1V, – 40°C ≤ TJ ≤ 110°C VIN = 2.7V, ∆VOUT = – 0.1V, 110°C < TJ ≤ 125°C 3.1 2.8 A A VIN = – 20V, VOUT = 0V Reverse Output Current (Note 10) LT1764-1.5 VOUT = 1.5V, VIN < 1.5V LT1764-1.8 VOUT = 1.8V, VIN < 1.8V LT1764-2.5 VOUT = 2.5V, VIN < 2.5V LT1764-3.3 VOUT = 3.3V, VIN < 3.3V LT1764 (Note 3) VOUT = 1.21V, VIN < 1.21V Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT1764 regulators are tested and specified under pulse load conditions such that TJ ≈ TA. The LT1764 is 100% tested at TA = 25°C. Performance at – 40°C and 125°C is assured by design, characterization and correlation with statistical process controls. Note 3: The LT1764 (adjustable version) is tested and specified for these conditions with the ADJ pin connected to the OUT pin. 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: To satisfy requirements for minimum input voltage, the LT1764 (adjustable version) is tested and specified for these conditions with an external resistor divider (two 4.12k resistors) for an output voltage of 2.42V. The external resistor divider will add a 300µA DC load on the output. ● 600 600 600 600 300 1 mA 1200 1200 1200 1200 600 µA µA µA µA µA Note 6: Dropout voltage is the minimum input to output voltage differential needed to maintain regulation at a specified output current. In dropout, the output voltage will be equal to: VIN – VDROPOUT. Note 7: GND pin current is tested with VIN = VOUT(NOMINAL) + 1V or VIN = 2.7V (whichever is greater) and a current source load. The GND pin current will decrease at higher input voltages. Note 8: ADJ pin bias current flows into the ADJ pin. Note 9: SHDN pin current flows into the SHDN pin. Note 10: Reverse output current is tested with the IN pin grounded and the OUT pin forced to the rated output voltage. This current flows into the OUT pin and out the GND pin. Note 11. For the LT1764, LT1764-1.5 and LT1764-1.8 dropout voltage will be limited by the minimum input voltage specification under some output voltage/load conditions. Note 12. All combinations of absolute maximum input voltage and absolute maximum output voltage cannot be achieved. The absolute maximum differential from input to output is ±20V. For example, with VIN = 20V, VOUT cannot be pulled below ground. 1764fb 4 LT1764 Series U W TYPICAL PERFOR A CE CHARACTERISTICS Typical Dropout Voltage Guaranteed Dropout Voltage GUARANTEED DROPOUT VOLTAGE (mV) 700 DROPOUT VOLTAGE (mV) 500 400 TJ = 125°C 300 200 TJ = 25°C 100 0 0 0.5 1.0 1.5 2.0 OUTPUT CURRENT (A) 2.5 = TEST POINTS 600 500 500 TJ ≤ 125°C 400 300 TJ ≤ 25°C 200 0 Quiescent Current LT1764 0.8 0.6 VIN = 6V RL = ∞ IL = 0 VSHDN = VIN 50 25 75 0 TEMPERATURE (°C) 0.5 2.0 1.5 1.0 OUTPUT CURRENT (A) IL = 1mA 2.56 1.82 2.54 1.81 1.80 1.79 1.78 3.34 1.220 3.28 3.26 3.24 75 50 25 TEMPERATURE (°C) 0 100 75 50 25 TEMPERATURE (°C) 2.48 2.46 2.42 – 50 – 25 125 100 125 1756 G07 75 50 25 TEMPERATURE (°C) 0 100 125 1756 G06 LT1764-1.8 Quiescent Current 40 IL = 1mA 1.215 1.210 1.205 1.200 1.190 – 50 – 25 TJ = 25°C RL = ∞ VSHDN = VIN 35 30 25 20 15 10 5 1.195 0 2.50 2.44 QUIESCENT CURRENT (mA) 1.225 ADJ PIN VOLTAGE (V) OUTPUT VOLTAGE (V) IL = 1mA 3.36 3.22 – 50 – 25 2.52 LT1764 ADJ Pin Voltage 1.230 125 IL = 1mA 1756 G05 LT1764-3.3 Output Voltage 3.30 100 LT1764-2.5 Output Voltage 1.83 1.76 – 50 – 25 125 3.32 50 25 75 0 TEMPERATURE (°C) 1764 G03 2.58 1764 G04 3.38 3.0 2.5 1.77 100 IL = 100mA 0 –50 –25 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) QUIESCENT CURRENT (mA) LT1764-1.8/2.5/3.3 0 –50 –25 IL = 0.5A LT1764-1.8 Output Voltage 1.84 1.0 0.2 IL = 1.5A 200 1764 G02 1.4 0.4 IL = 3A 300 IL = 1mA 1764 G01 1.2 400 100 100 0 3.0 Dropout Voltage 600 DROPOUT VOLTAGE (mV) 600 0 75 50 25 TEMPERATURE (°C) 0 100 125 1756 G08 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1764 G09 1764fb 5 LT1764 Series U W TYPICAL PERFOR A CE CHARACTERISTICS LT1764-2.5 Quiescent Current LT1764-3.3 Quiescent Current TJ = 25°C RL = ∞ VSHDN = VIN 1.6 TJ = 25°C RL = ∞ VSHDN = VIN 35 QUIESCENT CURRENT (mA) 30 25 20 15 10 5 30 25 20 15 10 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 1764 G10 LT1764-1.8 GND Pin Current 0 RL = 6Ω IL = 300mA* 7.5 5.0 RL = 18Ω IL = 100mA* 2.5 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 TJ = 25°C VSHDN = VIN *FOR VOUT = 2.5V 30 RL = 5Ω IL = 500mA* 25 20 RL = 25Ω IL = 100mA* 15 RL = 8.33Ω IL = 300mA* 10 10 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 150 8 9 GND PIN CURRENT (mA) RL = 4.33Ω IL = 300mA* 6 RL = 12.1Ω IL = 100mA* 3 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1764 G16 RL = 33Ω IL = 100mA* 20 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 60 RL = 1.2Ω IL = 1.5A* 0 TJ = 25°C VSHDN = VIN *FOR VOUT = 2.5V 160 RL = 2.57Ω IL = 0.7A* RL = 0.83Ω IL = 3A* 120 80 RL = 1.66Ω IL = 1.5A* 40 0 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 10 1764 G15 200 RL = 0.6Ω IL = 3A* 90 9 LT1764-2.5 GND Pin Current 30 2 RL = 11Ω IL = 300mA* 30 10 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.8V 120 9 RL = 6.6Ω IL = 500mA* 40 LT1764-1.8 GND Pin Current RL = 2.42Ω IL = 500mA* 1 50 1764 G14 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.21V 0 60 0 0 LT1764 GND Pin Current 12 TJ = 25°C VSHDN = VIN *FOR VOUT = 3.3V 70 10 1764 G13 15 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) LT1764-3.3 GND Pin Current 0 1 4 1764 G12 5 0 0 2 80 35 GND PIN CURRENT (mA) GND PIN CURRENT (mA) 10.0 0.4 10 GND PIN CURRENT (mA) TJ = 25°C VSHDN = VIN *FOR VOUT = 1.8V 12.5 0.6 LT1764-2.5 GND Pin Current 15.0 GND PIN CURRENT (mA) 9 40 RL = 3.6Ω IL = 500mA* 0.8 1764 G11 20.0 17.5 1.0 0 0 0 1.2 0.2 5 0 TJ = 25°C RL = 4.3k VSHDN = VIN 1.4 GND PIN CURRENT (mA) QUIESCENT CURRENT (mA) 35 0 LT1764 Quiescent Current 40 QUIESCENT CURRENT (mA) 40 9 10 1764 G17 0 1 2 RL = 3.57Ω IL = 0.7A* 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1764 G18 1764fb 6 LT1764 Series U W TYPICAL PERFOR A CE CHARACTERISTICS 200 150 TJ = 25°C VSHDN = VIN *FOR VOUT = 3.3V RL = 1.1Ω IL = 3A* 120 80 RL = 2.2Ω IL = 1.5A* RL = 4.71Ω IL = 0.7A* 40 GND Pin Current vs ILOAD 160 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.21V 120 GND PIN CURRENT (mA) 160 GND PIN CURRENT (mA) LT1764 GND Pin Current RL = 0.4Ω IL = 3A* 90 RL = 0.81Ω IL = 1.5A* 60 RL = 1.73Ω IL = 0.7A* VIN = VOUT(NOM) + 1V 140 GND PIN CURRENT (mA) LT1764-3.3 GND Pin Current 30 120 100 80 60 40 20 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 0 10 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 1764 G19 0.6 0.5 0.4 0.3 0.2 0.1 50 25 0 75 TEMPERATURE (°C) 100 0.7 0.6 IL = 1mA 0.5 0.4 0.3 0.2 6 5 4 3 2 0 50 25 0 75 TEMPERATURE (°C) 100 125 5 4 3 2 6 8 10 12 14 16 18 20 SHDN PIN VOLTAGE (V) 5 TJ = –50°C 3.0 CURRENT LIMIT (A) 6 4 Current Limit 3.5 7 2 6 4.0 VSHDN = 20V 8 0 1764 G24 ADJ Pin Bias Current ADJ PIN BIAS CURRENT (µA) SHDN PIN INPUT CURRENT (µA) 7 1764 G23 SHDN Pin Input Current 2.5 2.0 1.5 4 TJ = 125°C 3 TJ = 25°C 2 1.0 1 0.5 1 0 –50 –25 8 1 0 –50 –25 125 3.0 9 IL = 3A 0.8 1764 G22 9 2.5 SHDN Pin Input Current 0.1 0 –50 –25 1.0 2.0 1.5 OUTPUT CURRENT (A) 10 0.9 0.7 0.5 0 1764 G21 1.0 IL = 1mA 0.8 10 0 10 SHDN Pin Threshold (Off-to-On) SHDN PIN THRESHOLD (V) SHDN PIN THRESHOLD (V) 0.9 9 1764 G20 SHDN Pin Threshold (On-to-Off) 1.0 8 SHDN PIN INPUT CURRENT (µA) 0 50 25 0 75 TEMPERATURE (°C) 100 125 1764 G25 0 – 50 – 25 0 75 50 25 TEMPERATURE (°C) 0 100 125 1756 G26 0 2 4 6 8 10 12 14 16 18 20 INPUT/OUTPUT DIFFERENTIAL (V) 1764 G27 1764fb 7 LT1764 Series U W TYPICAL PERFOR A CE CHARACTERISTICS Current Limit Reverse Output Current VIN = 7V VOUT = 0V CURRENT LIMIT (A) 5 4 3 2 1 5.0 REVERSE OUTPUT CURRENT (mA) 6 4.5 LT1764 4.0 LT1764-1.8 3.5 3.0 LT1764-2.5 LT1764-3.3 2.5 TJ = 25°C VIN = 0V CURRENT FLOWS INTO OUTPUT PIN VOUT = VADJ (LT1764) VOUT = VFB (LT1764-1.8/-2.5/-3.3) 2.0 1.5 1.0 0.5 0 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 0 125 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE (V) 9 1764 G28 1764 G29 Ripple Rejection Reverse Output Current 80 VIN = 0V 0.9 VOUT = 1.21V (LT1764) = 1.8V (LT1764-1.8) V 0.8 OUT VOUT = 2.5V (LT1764-2.5) 0.7 VOUT = 3.3V (LT1764-3.3) 70 RIPPLE REJECTION (dB) REVERSE OUTPUT CURRENT (mA) 1.0 0.6 LT1764-1.8/-2.5/-3.3 0.5 0.4 0.3 LT1764 0.2 0.1 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 60 50 COUT = 100µF TANTALUM + 10 × 1µF CERAMIC 40 30 20 COUT = 10µF IL = 1.5A TANTALUM 10 VIN = VOUT(NOM) + 1V + 50mVRMS RIPPLE 0 100 100k 10 1k 10k FREQUENCY (Hz) Ripple Rejection 65 60 55 50 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 1764 G32 3.0 MINIMUM INPUT VOLTAGE (V) RIPPLE REJECTION (dB) LT1764 Minimum Input Voltage IL = 1.5A VIN = VOUT(NOM) + 1V + 0.5VP-P RIPPLE AT f = 120Hz 70 1M 1764 G31 1764 G30 75 10 2.5 IL = 3A 2.0 IL = 1.5A 1.5 IL = 500mA IL = 100mA 1.0 0.5 0 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 1764 G33 1764fb 8 LT1764 Series U W TYPICAL PERFOR A CE CHARACTERISTICS Load Regulation Output Noise Spectral Density OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) 10 LOAD REGULATION (mV) 5 LT1764 0 –5 LT1764-1.8 –10 LT1764-2.5 –15 LT1764-3.3 –20 ∆IL = 1mA TO 3A VIN = 2.7V (LT1764) VIN = VOUT(NOM) + 1V (LT1764-1.8/-2.5/-3.3) –25 –30 – 50 – 25 75 50 25 TEMPERATURE (°C) 100 0 125 1 COUT = 10µF ILOAD = 3A LT1764-3.3 LT1764-2.5 LT1764 LT1764-1.8 0.1 0.01 10 100 1k 10k FREQUENCY (Hz) 1764 G35 1764 G34 RMS Output Noise vs Load Current (10Hz to 100kHz) 40 COUT = 10µF 100k LT1764-3.3 10Hz to 100kHz Output Noise LT1764-3.3 OUTPUT NOISE (µVRMS) 35 30 LT1764-2.5 VOUT 100µV/ DIV 25 LT1764-1.8 20 LT1764 15 10 COUT = 10µF IL = 3A 5 0 0.0001 0.001 0.01 0.1 LOAD CURRENT (A) 1ms/DIV 1764 G37 10 1 1764 G36 0.1 0 VIN = 4.3V CIN = 3.3µF TANTALUM COUT = 10µF TANTALUM –0.1 –0.2 OUTPUT VOLTAGE DEVIATION (V) 0.2 LT1764-3.3 Transient Response 0.2 0.1 0 –0.1 VIN = 4.3V CIN = 33µF COUT = 100µF TANTALUM + 10 × 1µF CERAMIC –0.2 1.00 0.75 0.50 0.25 0 0 2 4 6 8 10 12 14 16 18 20 TIME (µs) 1764 G38 LOAD CURRENT (A) LOAD CURRENT (A) OUTPUT VOLTAGE DEVIATION (V) LT1764-3.3 Transient Response 3 2 1 0 0 2 4 6 8 10 12 14 16 18 20 TIME (µs) 1764 G39 1764fb 9 LT1764 Series U U U PI FU CTIO S (DD and TO-220/TSSOP) SHDN (Pin 1/Pin 10): Shutdown. The SHDN pin is used to put the LT1764 regulators into a low power shutdown state. The output will be off when the SHDN pin is pulled low. The SHDN pin can be driven either by 5V logic or open-collector logic with a pull-up resistor. The pull-up resistor is required to supply the pull-up current of the open-collector gate, normally several microamperes, and the SHDN pin current, typically 7µA. If unused, the SHDN pin must be connected to VIN. The device will be in the low power shutdown state if the SHDN pin is not connected. OUT (Pin 4/Pins 3, 4, 5): Output. The output supplies power to the load. A minimum output capacitor of 10µF is required to prevent oscillations. Larger output capacitors will be required for applications with large transient loads to limit peak voltage transients. See the Applications Information section for more information on output capacitance and reverse output characteristics. SENSE (Pin 5/Pin 6): Sense. For fixed voltage versions of the LT1764 (LT1764-1.8/LT1764-2.5/LT1764-3.3), 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 OUT pin of the regulator. In critical applications, small voltage drops are caused by the resistance (RP) of PC traces between the regulator and the load. These may be eliminated by connecting the SENSE pin to the output 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 600µA at the nominal rated output voltage. The SENSE pin can be pulled below ground (as in a dual supply system where the regulator load is returned to a negative supply) and still allow the device to start and operate. IN (Pin 2/Pins 12, 13, 14): Input. Power is supplied to the device through the IN pin. A bypass capacitor is required on this pin if the device is more than six 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 LT1764 regulators are designed to withstand reverse voltages on the IN pin with respect to ground and the OUT pin. In the case of a reverse input, which can happen if a battery is plugged in backwards, the device will act as if there is a diode in series with its input. There will be no reverse current flow into the regulator and no reverse voltage will appear at the load. The device will protect both itself and the load. ADJ (Pin 5/Pin 6): Adjust. For the adjustable LT1764, this is the input to the error amplifier. This pin is internally clamped to ±7V. It has a bias current of 3µA which flows into the pin. The ADJ pin voltage is 1.21V referenced to ground and the output voltage range is 1.21V to 20V. GND (Pin 3/Pins 1, 7, 8, 9, 16, 17): Ground. The exposed pad (FE Package) is ground and must be soldered to the PCB for rated thermal performance. 2 IN OUT 4 RP LT1764 + VIN 1 SHDN SENSE GND + 5 LOAD 3 RP 1764 F01 Figure 1. Kelvin Sense Connection 1764fb 10 LT1764 Series U W U U APPLICATIO S I FOR ATIO The LT1764 series are 3A low dropout regulators optimized for fast transient response. The devices are capable of supplying 3A at a dropout voltage of 340mV. The low operating quiescent current (1mA) drops to less than 1µA in shutdown. In addition to the low quiescent current, the LT1764 regulators incorporate several protection features which make them ideal for use in battery-powered systems. The devices are protected against both reverse input and reverse output voltages. In battery backup applications where the output can be held up by a backup battery when the input is pulled to ground, the LT1764-X acts like it has a diode in series with its output and prevents reverse current flow. Additionally, in dual supply applications where the regulator load is returned to a negative supply, the output can be pulled below ground by as much as 20V and still allow the device to start and operate. Adjustable Operation The adjustable version of the LT1764 has an output voltage range of 1.21V to 20V. The output voltage is set by the ratio of two external resistors as shown in Figure 2. The device servos the output to maintain the voltage at the ADJ pin at 1.21V referenced to ground. The current in R1 is then equal to 1.21V/R1 and the current in R2 is the current in R1 plus the ADJ pin bias current. The ADJ pin bias current, 3µA at 25°C, flows through R2 into the ADJ pin. The output voltage can be calculated using the formula in Figure 2. The value of R1 should be less than 4.17k to minimize errors in the output voltage caused by the ADJ pin bias current. Note that in shutdown the output is turned off and the divider current will be zero. The adjustable device is tested and specified with the ADJ pin tied to the OUT pin for an output voltage of 1.21V. Specifications for output voltages greater than 1.21V will IN VIN OUT VOUT + R2 LT1764 ADJ GND R1 1764 F02 ⎛ R2⎞ VOUT = 1.21V ⎜ 1 + ⎟ + (IADJ )(R2) ⎝ R1⎠ VADJ = 1.21V IADJ = 3µA AT 25°C OUTPUT RANGE = 1.21V TO 20V Figure 2. Adjustable Operation be proportional to the ratio of the desired output voltage to 1.21V: VOUT/1.21V. For example, load regulation for an output current change of 1mA to 3A is – 3mV typical at VOUT = 1.21V. At VOUT = 5V, load regulation is: (5V/1.21V)(–3mV) = – 12.4mV Output Capacitance and Transient Response The LT1764 regulators are designed to be stable with a wide range of output capacitors. The ESR of the output capacitor affects stability, most notably with small capacitors. A minimum output capacitor of 10µF with an ESR in the range of 50mΩ to 3Ω is recommended to prevent oscillations. Larger values of output capacitance can decrease the peak deviations and provide improved transient response for larger load current changes. Bypass capacitors, used to decouple individual components powered by the LT1764-X, will increase the effective output capacitor value. Extra consideration must be given to the use of ceramic capacitors. Ceramic capacitors are manufactured with a variety of dielectrics, each with different behavior across temperature and applied voltage. The most common dielectrics used are specified with EIA temperature characteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high capacitances in a small package, but they tend to have strong voltage and temperature coefficients as shown in Figures 3 and 4. When used with a 5V regulator, a 16V 10µF Y5V capacitor can exhibit an effective value as low as 1µF to 2µF for the DC bias voltage applied and over the operating temperature range. The X5R and X7R dielectrics result in more stable characteristics and are more suitable for use as the output capacitor. The X7R type has better stability across temperature, while the X5R is less expensive and is available in higher values. Care still must be exercised when using X5R and X7R capacitors; the X5R and X7R codes only specify operating temperature range and maximum capacitance change over temperature. Capacitance change due to DC bias with X5R and X7R capacitors is better than Y5V and Z5U capacitors, but can still be significant enough to drop capacitor values below appropriate levels. Capacitor DC bias characteristics tend to improve as component case size increases, but expected capacitance at operating voltage should be verified. 1764fb 11 LT1764 Series U W U U APPLICATIO S I FOR ATIO 20 The protection is designed to provide some output current at all values of input-to-output voltage up to the device breakdown. BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF 0 CHANGE IN VALUE (%) X5R –20 –40 –60 Y5V –80 –100 0 2 14 8 6 4 10 12 DC BIAS VOLTAGE (V) 16 1764 F03 Figure 3. Ceramic Capacitor DC Bias Characteristics The problem occurs with a heavy output load when the input voltage is high and the output voltage is low. Common situations are immediately after the removal of a short circuit or when the SHDN pin is pulled high after the input voltage has already been turned on. The load line for such a load may intersect the output current curve at two points. If this happens, there are two stable output operating points for the regulator. With this double intersection, the input power supply may need to be cycled down to zero and brought up again to make the output recover. 40 CHANGE IN VALUE (%) 20 X5R 0 –20 –40 Y5V –60 –80 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF –100 –50 –25 50 25 75 0 TEMPERATURE (°C) When power is first turned on, as the input voltage rises, the output follows the input, allowing the regulator to start up into very heavy loads. During the start-up, as the input voltage is rising, the input-to-output voltage differential is small, allowing the regulator to supply large output currents. With a high input voltage, a problem can occur wherein removal of an output short will not allow the output voltage to recover. Other regulators, such as the LT1085, also exhibit this phenomenon, so it is not unique to the LT1764 series. 100 125 1764 F04 Figure 4. Ceramic Capacitor Temperature Characteristics Voltage and temperature coefficients are not the only sources of problems. Some ceramic capacitors have a piezoelectric response. A piezoelectric device generates voltage across its terminals due to mechanical stress, similar to the way a piezoelectric accelerometer or microphone works. For a ceramic capacitor the stress can be induced by vibrations in the system or thermal transients. Overload Recovery Like many IC power regulators, the LT1764-X has safe operating area protection. The safe area protection decreases the current limit as input-to-output voltage increases and keeps the power transistor inside a safe operating region for all values of input-to-output voltage. Output Voltage Noise The LT1764 regulators have been designed to provide low output voltage noise over the 10Hz to 100kHz bandwidth while operating at full load. Output voltage noise is typically 50nV√Hz over this frequency bandwidth for the LT1764 (adjustable version). For higher output voltages (generated by using a resistor divider), the output voltage noise will be gained up accordingly. This results in RMS noise over the 10Hz to 100kHz bandwidth of 15µVRMS for the LT1764 increasing to 37µVRMS for the LT1764-3.3. Higher values of output voltage noise may be measured when care is not exercised with regards to circuit layout and testing. Crosstalk from nearby traces can induce unwanted noise onto the output of the LT1764-X. Power supply ripple rejection must also be considered; the LT1764 regulators do not have unlimited power supply rejection and will pass a small portion of the input noise through to the output. 1764fb 12 LT1764 Series U U W U APPLICATIONS INFORMATION Table 2. FE Package, 16-Lead TSSOP Thermal Considerations The power handling capability of the device is limited by the maximum rated junction temperature (125°C). The power dissipated by the device is made up of two components: COPPER AREA TOPSIDE* BACKSIDE BOARD AREA THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 2500mm2 2500mm2 2500mm2 38°C/W 2 2 2 43°C/W 2500mm 2 2500mm 48°C/W 2500mm2 2500mm2 60°C/W 1000mm 225mm 2 2500mm 2 2500mm 1. Output current multiplied by the input/output voltage differential: (IOUT)(VIN – VOUT), and * Device is mounted on topside 2. GND pin current multiplied by the input voltage: (IGND)(VIN). T Package, 5-Lead TO-220 Thermal Resistance (Junction-to-Case) = 2.5°C/W The GND pin current can be found using the GND Pin Current curves in the Typical Performance Characteristics. Power dissipation will be equal to the sum of the two components listed above. Calculating Junction Temperature The LT1764 series regulators have internal thermal limiting designed to protect the device during overload conditions. For continuous normal 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. Surface mount heatsinks and plated through-holes can also be used to spread the heat generated by power devices. The following tables list thermal resistance for several different board sizes and copper areas. All measurements were taken in still air on 1/16" FR-4 board with one ounce copper. Table 1. Q Package, 5-Lead DD COPPER AREA TOPSIDE* BACKSIDE BOARD AREA THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 2500mm2 2500mm2 2500mm2 23°C/W 2 2 2 25°C/W 33°C/W 1000mm 2500mm 2500mm 125mm2 2500mm2 2500mm2 100mm2 Example: Given an output voltage of 3.3V, an input voltage range of 4V to 6V, an output current range of 0mA to 500mA and a maximum ambient temperature of 50°C, what will the maximum junction temperature be? The power dissipated by the device will be equal to: IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)) where, IOUT(MAX) = 500mA VIN(MAX) = 6V IGND at (IOUT = 500mA, VIN = 6V) = 10mA So, P = 500mA(6V – 3.3V) + 10mA(6V) = 1.41W Using a DD package, the thermal resistance will be in the range of 23°C/W to 33°C/W depending on the copper area. So the junction temperature rise above ambient will be approximately equal to: 1.41W(28°C/W) = 39.5°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 + 39.5°C = 89.5°C * Device is mounted on topside 1764fb 13 LT1764 Series U W U U APPLICATIONS INFORMATION Protection Features The LT1764 regulators incorporate several protection features which make them 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 devices are protected against reverse input voltages, reverse output voltages and reverse voltages from output to input. 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 20V. Current flow into the device will be limited to less than 1mA and no negative voltage will appear at the output. The device will protect both itself and the load. This provides protection against batteries which can be plugged in backward. The output of the LT1764-X can be pulled below ground without damaging the device. If the input is left open circuit or grounded, the output can be pulled below ground by 20V. For fixed voltage versions, the output will act like a large resistor, typically 5k or higher, limiting current flow to typically less than 600µA. For adjustable versions, the output will act like an open circuit; no current will flow out of the pin. If the input is powered by a voltage source, the output will source the short-circuit current of the device and will protect itself by thermal limiting. In this case, grounding the SHDN pin will turn off the device and stop the output from sourcing the short-circuit current. The ADJ pin of the adjustable device can be pulled above or below ground by as much as 7V without damaging the device. If the input is left open circuit or grounded, the ADJ pin will act like an open circuit when pulled below ground and like a large resistor (typically 5k) in series with a diode when pulled above ground. In situations where the ADJ pin is connected to a resistor divider that would pull the ADJ pin above its 7V clamp voltage if the output is pulled high, the ADJ pin input current must be limited to less than 5mA. For example, a resistor divider is used to provide a regulated 1.5V output from the 1.21V reference when the output is forced to 20V. The top resistor of the resistor divider must be chosen to limit the current into the ADJ pin to less than 5mA when the ADJ pin is at 7V. The 13V difference between OUT and ADJ pins divided by the 5mA maximum current into the ADJ pin yields a minimum top resistor value of 2.6k. 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 follow the curve shown in Figure 5. When the IN pin of the LT1764-X is forced below the OUT pin or the OUT pin is pulled above the IN pin, input current will typically drop to less than 2µA. This can happen if the input of the device is connected to a discharged (low voltage) battery and the output is held up by either a backup battery or a second regulator circuit. The state of the SHDN pin will have no effect on the reverse output current when the output is pulled above the input. REVERSE OUTPUT CURRENT (mA) 5.0 4.5 TJ = 25°C VIN = OV CURRENT FLOWS INTO OUTPUT PIN VOUT = VADJ (LT1764) VOUT = VFB (LT1764-1.8, LT1764-2.5, LT1764-3.3) LT1764 4.0 3.5 LT1764-1.8 3.0 2.5 2.0 LT1764-2.5 1.5 1.0 LT1764-3.3 0.5 0 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE (V) 9 10 1764 F05 Figure 5. Reverse Output Current 1764fb 14 LT1764 Series U TYPICAL APPLICATIO S SCR Preregulator Provides Efficiency Over Line Variations L1 500µH NTE5437 LT1764-3.3 L2 90V AC TO 140V AC + 1N4148 10V AC AT 115VIN IN SHDN 10000µF OUT FB 22µF GND 1k VOUT 3.3V 3A + 34k* 10V AC AT 115VIN 12.1k* NTE5437 1N4002 1N4002 V+ “SYNC” 1N4002 TO ALL “V +” POINTS 2.4k + + 22µF 750Ω 1N4148 200k C1A 1/2 LT1018 0.1µF – V+ 0.033µF 750Ω V+ + C1B 1/2 LT1018 + 1N4148 A1 LT1006 – L1: COILTRONICS CTX500-2-52 L2: STANCOR P-8560 *1% FILM RESISTOR 10k 10k 10k V+ – 1µF V+ LT1004 1.2V 1764 TA03 1764fb 15 LT1764 Series U TYPICAL APPLICATIO S Adjustable Current Source R5 0.01Ω + VIN > 2.7V C1 10µF LT1004-1.2 IN OUT LT1764-1.8 SHDN FB R1 1k R2 40.2k R4 2.2k R6 2.2k LOAD R8 100k GND R3 2k C3 1µF R7 470Ω ADJUST R1 FOR 0A TO 3A CONSTANT CURRENT 2 – 3 + 8 1/2 LT1366 C2 3.3µF 1 4 1764 TA04 1764fb 16 LT1764 Series U PACKAGE DESCRIPTION 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 1764fb 17 LT1764 Series U PACKAGE DESCRIPTION T Package 5-Lead Plastic TO-220 (Standard) (LTC DWG # 05-08-1421) 0.390 – 0.415 (9.906 – 10.541) 0.165 – 0.180 (4.191 – 4.572) 0.147 – 0.155 (3.734 – 3.937) DIA 0.045 – 0.055 (1.143 – 1.397) 0.230 – 0.270 (5.842 – 6.858) 0.460 – 0.500 (11.684 – 12.700) 0.570 – 0.620 (14.478 – 15.748) 0.330 – 0.370 (8.382 – 9.398) 0.620 (15.75) TYP 0.700 – 0.728 (17.78 – 18.491) SEATING PLANE 0.152 – 0.202 0.260 – 0.320 (3.861 – 5.131) (6.60 – 8.13) 0.095 – 0.115 (2.413 – 2.921) 0.155 – 0.195* (3.937 – 4.953) 0.013 – 0.023 (0.330 – 0.584) BSC 0.067 (1.70) 0.028 – 0.038 (0.711 – 0.965) 0.135 – 0.165 (3.429 – 4.191) * MEASURED AT THE SEATING PLANE T5 (TO-220) 0399 1764fb 18 LT1764 Series U PACKAGE DESCRIPTION FE Package 16-Lead Plastic TSSOP (4.4mm) (Reference LTC DWG # 05-08-1663) Exposed Pad Variation BB 4.90 – 5.10* (.193 – .201) 3.58 (.141) 3.58 (.141) 16 1514 13 12 1110 6.60 ±0.10 9 2.94 (.116) 4.50 ±0.10 2.94 6.40 (.116) (.252) BSC SEE NOTE 4 0.45 ±0.05 1.05 ±0.10 0.65 BSC 1 2 3 4 5 6 7 8 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50* (.169 – .177) 0.09 – 0.20 (.0035 – .0079) 0.50 – 0.75 (.020 – .030) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) 3. DRAWING NOT TO SCALE 0.25 REF 1.10 (.0433) MAX 0° – 8° 0.65 (.0256) BSC 0.195 – 0.30 (.0077 – .0118) TYP 0.05 – 0.15 (.002 – .006) FE16 (BB) TSSOP 0204 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE 1764fb 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. 19 LT1764 Series U TYPICAL APPLICATIO Paralleling of Regulators for Higher Output Current R1 0.01Ω + IN OUT LT1764-3.3 SHDN FB C1 100µF VIN > 3.7V + 3.3V 6A C2 22µF GND R2 0.01Ω IN SHDN OUT LT1764 SHDN R7 4.12k GND R3 2.2k R4 2.2k 3 + 8 – 4 R5 1k 1 1/2 LT1366 2 R6 6.65k ADJ C3 0.01µF 1764 TA05 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1120 125mA Low Dropout Regulator with 20µA IQ Includes 2.5V Reference and Comparator LT1121 150mA Micropower Low Dropout Regulator 30µA IQ, SOT-223 Package LT1129 700mA Micropower Low Dropout Regulator 50µA Quiescent Current LT1175 500mA Negative Low Dropout Micropower Regulator 45µA IQ, 0.26V Dropout Voltage, SOT-223 Package LT1374 4.5A, 500kHz Step-Down Converter 4.5A, 0.07Ω Internal Switch, SO-8 Package LT1521 300mA Low Dropout Micropower Regulator with Shutdown 15µA IQ, Reverse Battery Protection LT1529 3A Low Dropout Regulator with 50µA IQ 500mV Dropout Voltage LT1573 UltraFastTM Transient Response Low Dropout Regulator Drives External PNP LT1575 UltraFast Transient Response Low Dropout Regulator Drives External N-Channel MOSFET LT1735 Synchronous Step-Down Converter High Efficiency, OPTI-LOOP® Compensation LT1761 Series 100mA, Low Noise, Low Dropout Micropower Regulators in SOT-23 20µA Quiescent Current, 20µVRMS Noise, SOT-23 Package LT1762 Series 150mA, Low Noise, LDO Micropower Regulators 25µA Quiescent Current, 20µVRMS Noise, MSOP Package LT1763 Series 500mA, Low Noise, LDO Micropower Regulators 30µA Quiescent Current, 20µVRMS Noise, SO-8 Package LT1962 300mA, Low Noise, LDO Micropower Regulator 20µVRMS Noise, MSOP Package LT1963 1.5A, Low Noise, Fast Transient Response LDO 40µVRMS Noise, SOT-223 Package UltraFast is a trademark of Linear Technology Corporation. OPTI-LOOP is a registered trademark of Linear Technology Corporation. 1764fb 20 Linear Technology Corporation LT 1205 REV B • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2005