AN7810F

Voltage Regulators AN78xx/AN78xxF Series 3-pin positive output voltage regulator (1 A type) I Overview The AN78xx series and the AN78xxF series are 3pin, fixed positive output type monolithic voltage regulators. Stabilized fixed output voltage is obtained from unstable DC input voltage without using any external components. 11 types of fixed output voltage are available; 5V, 6V, 7V, 8V, 9V, 10V, 12V, 15V, 18V, 20V, and 24V. They can be used widely in power circuits with current capacity of up to 1A. AN78xx series (10.35) 10.0±0.3 φ3.7±0.1 Unit: mm 4.5±0.2 1.4±0.1 15.4±0.2 (4.5) 1.4 +0.15 –0.05 0.8 +0.15 –0.05 I Features • No external components • Output voltage: 5V, 6V, 7V, 8V, 9V, 10V, 12V, 15V, 18V, 20V, 24V • Built-in overcurrent limit circuit • Built-in thermal overload protection circuit • Built-in ASO (area of safe operation) protection circuit (13.6) 2.54 2.54 0.45 +0.2 –0.0 (2.0) (2.5) 10.5±0.3 HSIP003-P-0000 AN78xxF series 10.50±0.30 φ5.30 (4.30) (1.73) φ3.10±0.10 Unit: mm 2.77±0.30 16.70±0.30 17.00±0.25 13.60±0.25 4.50±0.25 2.54 (0.40) 0.80±0.20 2.00±0.25 1.40±0.20 4.50±0.30 1 2 3 0.40+0.10 −0.05 2.50±0.25 I Block Diagram HSIP003-P-0000A 1 Pass Tr Q1 Current Source Current Limiter RSC 3 Input Output Starter Voltage Reference + Error Amp. − R2 Thermal Protection R1 2 Common 8.70±0.30 4.20±0.25 3.80±0.25 12.5±0.2 17.0±0.2 26.1±0.2 29.0±0.3 8.7±0.2 2.9±0.1 1: Input 2: Common 3: Output 1: Input 2: Common 3: Output 1 AN78xx/AN78xxF Series I Absolute Maximum Ratings at Ta = 25°C Parameter Input voltage Power dissipation AN78xx series AN78xxF series Symbol VI PD Topr Tstg Rating 35 *1 40 *2 15 *3 10.25 *3 −30 to +80 −55 to +150 Voltage Regulators Unit V V W °C °C Operating ambient temperature Storage temperature *1 AN7805/F, AN7806/F, AN7807/F, AN7808/F, AN7809/F, AN7810/F, AN7812/F, AN7815/F, AN7818/F *2 AN7820/F, AN7824/F *3 Follow the derating curve. When Tj exceeds 150°C, the internal circuit cuts off the output. I Electrical Characteristics at Ta = 25°C • AN7805, AN7805F (5V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions Tj = 25°C VI = 8 to 20V, IO = 5mA to 1A, Tj = 0 to 125°C, PD ≤ * VI = 7.5 to 25 V, Tj = 25°C VI = 8 to 12V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 7.5 to 25V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz VI = 8 to 18V, IO = 100mA, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 25V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C 62 2 17 700 2 − 0.3 40 Min 4.8 4.75 3 1 15 5 3.9 Typ 5 Max 5.2 5.25 100 50 100 50 8 1.3 0.5 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 10V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W 2 Voltage Regulators I Electrical Characteristics at Ta = 25°C (continued) • AN7806, 7806F (6V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions Tj = 25°C VI = 9 to 21V, IO = 5mA to 1A, Tj = 0 to 125°C, PD ≤ * VI = 8.5 to 25V, Tj = 25°C VI = 9 to 13V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 8.5 to 25V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz AN78xx/AN78xxF Series Min 5.75 5.7 Typ 6 Max 6.25 6.3 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C 5 1.5 14 4 3.9 120 60 120 60 8 1.3 0.5 40 59 2 17 700 2 − 0.4 VI = 9 to 19V, IO = 100mA, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 25V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 11V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W • AN7807, 7807F (7V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions Tj = 25°C VI = 10 to 22V, IO = 5mA to 1A, Tj = 0 to 125°C, PD ≤ * VI = 9.5 to 25V, Tj = 25°C VI = 10 to 15V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 9.5 to 25V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz VI = 10 to 20V, IO = 100mA, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 25V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C 57 2 16 700 2 − 0.5 46 Min 6.7 6.6 5 1.5 14 4 3.9 Typ 7 Max 7.3 7.4 140 70 140 70 8 1 0.5 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 12V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W 3 AN78xx/AN78xxF Series I Electrical Characteristics at Ta = 25°C (continued) • AN7808, 7808F (8V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions Tj = 25°C VI = 11 to 23V, IO = 5mA to 1A, Tj = 0 to 125°C, PD ≤ * VI = 10.5 to 25V, Tj = 25°C VI = 11 to 17V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 10.5 to 25V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz VI = 11.5 to 21.5V, IO = 100mA, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 25V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C Voltage Regulators Min 7.7 7.6 Typ 8 Max 8.3 8.4 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C 6 2 12 4 3.9 160 80 160 80 8 1 0.5 52 56 2 16 700 2 − 0.5 Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 14V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W • AN7809, 7809F (9V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions Tj = 25°C VI = 12 to 24V, IO = 5mA to 1A, Tj = 0 to 125°C, PD ≤ * VI = 11.5 to 26V, Tj = 25°C VI = 12 to 18V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 11.5 to 26V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz VI = 12 to 22V, IO = 100mA, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 26V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C 56 2 16 700 2 − 0.5 57 Min 8.65 8.55 7 2 12 4 3.9 Typ 9 Max 9.35 9.45 180 90 180 90 8 1 0.5 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 15V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W 4 Voltage Regulators I Electrical Characteristics at Ta = 25°C (continued) • AN7810, 7810F (10V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions AN78xx/AN78xxF Series Min 9.6 9.5 Typ 10 Max 10.4 10.5 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C Tj = 25°C VI = 13 to 25V, IO = 5mA to 1A, Tj = 0 to 125°C, PD ≤ * VI = 12.5 to 27V, Tj = 25°C VI = 13 to 19V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 12.5 to 27V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz VI = 13 to 23V, IO = 100mA, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 27V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C 8 2.5 12 4 3.9 200 100 200 100 8 1 0.5 63 56 2 16 700 2 − 0.6 Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 16V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W • AN7812, 7812F (12V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions Tj = 25°C VI = 15 to 27V, IO = 5mA to 1A, Tj = 0 to 125°C, PD ≤ * VI = 14.5 to 30V, Tj = 25°C VI = 16 to 22V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 14.5 to 30V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz VI = 15 to 25V, IO = 100mA, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 30V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C 55 2 18 700 2 − 0.8 75 Min 11.5 11.4 10 3 12 4 4 Typ 12 Max 12.5 12.6 240 120 240 120 8 1 0.5 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 19V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W 5 AN78xx/AN78xxF Series I Electrical Characteristics at Ta = 25°C (continued) • AN7815, 7815F (15V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions Tj = 25°C VI = 18 to 30V, IO = 5mA to 1A, Tj = 0 to 125°C, PD ≤ * VI = 17.5 to 30V, Tj = 25°C VI = 20 to 26V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 17.5 to 30V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz VI = 18.5 to 28.5V, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 30V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C Voltage Regulators Min 14.4 14.25 Typ 15 Max 15.6 15.75 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C 11 3 12 4 4 300 150 300 150 8 1 0.5 90 54 2 19 700 2 −1 Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 23V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W • AN7818, 7818F (18V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions Tj = 25°C VI = 21 to 33V, IO = 5mA to 1A, Tj = 0 to 125°C, PD ≤ * VI = 21 to 33V, Tj = 25°C VI = 24 to 30V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 21 to 33V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz VI = 22 to 32V, IO = 100mA, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 35V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C 53 2 16 700 2 −1.1 110 Min 17.3 17.1 14 4 12 4 4.1 Typ 18 Max 18.7 18.9 360 180 360 180 8 1 0.5 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 27V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W 6 Voltage Regulators I Electrical Characteristics at Ta = 25°C (continued) • AN7820, 7820F (20V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions AN78xx/AN78xxF Series Min 19.2 19 Typ 20 Max 20.8 21 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C Tj = 25°C VI = 24 to 35V, IO = 5mA to 1A, Tj = 0 to 125°C, PD ≤ * VI = 23 to 35V, Tj = 25°C VI = 26 to 32V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 23 to 35V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz VI = 24 to 34V, IO = 100mA, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 35V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C 15 5 12 4 4.1 400 200 400 200 8 1 0.5 110 53 2 22 700 2 −1.2 Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 29V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W • AN7824, 7824F (24V type) Parameter Output voltage Output voltage tolerance Line regulation Load regulation Bias current Bias current fluctuation to input Bias current fluctuation to load Output noise voltage Ripple rejection ratio Minimum input/output voltage difference Output impedance Output short-circuit current Peak output current Output voltage temperature coefficient Symbol VO VO REGIN REGL IBias ∆IBias(IN) ∆IBias(L) Vno RR VDIF(min) ZO IO(Short) IO(Peak) ∆VO/Ta Conditions Tj = 25°C VI = 28 to 38V, IO = 5mA to 1A, Tj = 0 to 125°C, PD≤ * VI = 27 to 38V, Tj = 25°C VI = 30 to 36V, Tj = 25°C IO = 5mA to 1.5A, Tj = 25°C IO = 250 to 750mA, Tj = 25°C Tj = 25°C VI = 27 to 38V, Tj = 25°C IO = 5mA to 1A, Tj = 25°C f = 10Hz to 100kHz VI = 28 to 38V, IO = 100mA, f = 120Hz IO = 1A, Tj = 25°C f = 1kHz VI = 38V, Tj = 25°C Tj = 25°C IO = 5mA, Tj = 0 to 125°C 50 2 28 700 2 −1.4 170 Min 23 22.8 18 6 12 4 4.1 Typ 24 Max 25 25.2 480 240 480 240 8 1 0.5 Unit V V mV mV mV mV mA mA mA µV dB V mΩ mA A mV/°C Note 1) The specified condition Tj = 25°C means that the test should be carried out within so short a test time (within 10ms) that the characteristic value drift due to the chip junction temperature rise can be ignored. Note 2) Unless otherwise specified, VI = 33V, IO = 500mA, CI = 0.33µF and CO = 0.1µF. * AN78xx series: 15W, AN78xxF series: 10.25W 7 AN78xx/AN78xxF Series I Main Characteristic Curve 16 14 (1) 16 14 Voltage Regulators Minimum input/output voltage difference VDIF(min.) (V) PD  Ta (AN78xx series) PD  Ta (AN78xxF series) VDIF(min.)  Tj 2.4 Power dissipation PD (W) 12 10 8 (3) 6 4 2 0 Power dissipation PD (W) (2) 2.0 IO = 1A 500mA 200mA 12 (1) 1.6 10 8 (2) 1.2 20mA 6 (3) 0.8 0mA 4 2 0 0.4 (4) 0 40 80 120 160 (4) 0 40 80 120 160 0 −40 0 40 80 120 160 Ambient temperature Ta (°C) Ambient temperature Ta (°C) Junction temperature Tj (°C) Thermal resistance value: Rth(j-c) = 5°C/W (max.) Rth(j-a) = 65°C/W (max.) Installation condition to heat sink Tightening torque 6kg·cm Heat radiation compound used (1) (2) (3) (4) Infinite heat sink: 15.0W 5°C/W heat sink: 12.5W 15°C/W heat sink: 6.3W Without heat sink: 1.923W Thermal resistance value: Rth(j-c) = 12.2°C/W (max.) Rth(j-a) = 65°C/W (max.) Installation condition to heat sink Tightening torque 6kg·cm Heat radiation compound used (1) Infinite heat sink: 10.25W (2) 5°C/W heat sink: 7.3W (3) 15°C/W heat sink: 4.5W (4) Without heat sink: 1.923W Input transient response Input voltage VI (V) Output voltage fluctuation (V) 20 AN7805 15 Load transient response AN7805 Current limiting characteristic Load current IO (A) 7 6 VI = 10V Tj = 25°C AN7805 2 1 Output voltage VO (V) 5 4 3 2 1 0 10 Output voltage fluctuation (mV) 0 1 10 5 0 0 −10 −20 −1 −2 0 2 4 6 8 10 0 10 20 30 40 50 0 0.6 1.2 1.8 2.4 Time t (µs) Time t (µs) Output current IO (A) 8 Voltage Regulators I Basic Regulator Circuit Input 1 3 Output AN78xx/AN78xxF Series CI AN78xx AN78xxF 2 Common CO CI : CI is necessary when the input line is long. CO: CO improves the transient response. I Usage Notes 1. Cautions for a basic circuit Di VI 1 2 3 VO CI CO Figure 1 CI: When a wiring from a smoothing circuit to a three-pin regulator is long, it is likely to oscillate in output. A capacitor of 0.1µF to 0.47µF should be connected near an input pin. CO: When any sudden change of load current is likely to occur, connect an electrolytic capacitor of 10µF to 100µF to improve a transitional response of output voltage. Di: Normally unnecessary. But add it in the case that there is a residual voltage at the output capacitor Co even after switching off the supply power because a current is likely to flow into an output pin of the IC and damage the IC. 2. Other caution items 1) Short-circuit between the input pin and GND pin If the input pin is short-circuitted to GND or is cut off when a large capacitance capacitor has been connected to the IC's load, a voltage of a capacitor connected to an output pin is applied between input/output of the IC and this likely results in damage of the IC. It is necessary, therefore, to connect a diode, as shown in figure 2, to counter the reverse bias between input/output pins. In 1 2 GND 3 Out Output + − CO Figure 2 2) Floating of GND pin If a GND pin is made floating in an operating mode, an unstabilized input voltage is outputted. In this case, a thermal protection circuit inside the IC does not normally operate. In this state, if the load is short-circuited or overloaded, it is likely to damage the IC. I Application Circuit Examples 1. Current bootstrap circuit VI Q1 3Ω 1 0.33µF 3 2. Adjustable output regulator VI IO VO 1 AN78xx AN78xxF 2 3 VO' R2 AN78xx AN78xxF 2 VO 0.1µF IBias R1 V' VO = VO' + IBias + RO R1 2 Note) VO varies due to sample to sample variation of IBias. Never fail to adjust individually with R1. 9