TC1070

50mA ADJUSTABLE CMOS LDO WITH SHUTDOWN PRELIMINARY INFORMATION TC1070 TC1070 50mA ADJUSTABLE CMOS LDO WITH SHUTDOWN FEATURES s s s s s s s s Zero Ground Current for Longer Battery Life! Adjustable Output Voltage Very Low Dropout Voltage Guaranteed 50mA Output Power-Saving Shutdown Mode Over-Current and Over-Temperature Protection Space-Saving SOT-23A-5 Package Pin Compatible with LP2980 and MIC5205 Regulators GENERAL DESCRIPTION The TC1070 is an adjustable LDO designed to supercede a variety of older (bipolar) voltage regulators. Designed specifically for battery-operated systems, the TC1070’s CMOS construction eliminates wasted ground current, significantly extending battery life. Total supply current is typically 50µA at full load (20 to 60 times lower than in bipolar regulators!). TC1070 key features include ultra low noise operation very low dropout voltage (typically 100mV at full load) and internal feed-forward compensation for fast response to step changes in load. Supply current is reduced to less than 1µA when the shutdown input is low. The TC1070 incorporates both over-temperature and over-current protection. Output voltage is programmed with a simple resistor divider from VOUT to ADJ. The TC1070 is stable with an output capacitor of only 1µF and has a maximum output current of 50mA. For higher output versions, please see the TC1107, TC1108 (IOUT = 300mA) data sheets. APPLICATIONS s s s s s s s Battery Operated Systems Portable Computers Medical Instruments Instrumentation Cellular / GSM / PHS Phones Linear Post-Regulator for SMPS Pagers ORDERING INFORMATION TYPICAL APPLICATION Part No. TC1070VCT Output Voltage **(V) Package Adjustable Junction Temp. Range SOT-23A-5* – 40°C to +125°C NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A) ** Other output voltages available. Please contact TelCom Semiconductor for details VIN 1 VIN VOUT 5 C1 1µF VOUT PIN CONFIGURATION VOUT ADJ 4 2 GND TC1070 5 R1 TC1070 (SOT-23A-5*) 3 SHDN ADJ 4 1 R2 2 3 TOP VIEW VIN GND SHDN NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A) Shutdown Control (from Power Control Logic) VOUT = VREF x [ R2 + 1 R1 ] TC1070-01 6/13/97 TelCom Semiconductor reserves the right to make changes in the circuitry1 and specifications ot its devices. PRELIMINARY INFORMATION 50mA ADJUSTABLE CMOS LDO WITH SHUTDOWN TC1070 ABSOLUTE MAXIMUM RATINGS* Input Voltage .................................................................7V Output Voltage .................................. (– 0.3) to (VIN + 0.3) Power Dissipation .................... Internally Limited (Note 7) Operating Temperature .................... – 40°C < TJ < 125°C Storage Temperature ............................ – 65°C to +150°C Maximum Voltage on Any Pin ........... VIN + 0.3V to – 0.3V Lead Temperature (Soldering, 10 Sec.) ................ +260°C *Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS: VIN = VOUT + 1V, IL = 0.1mA, CL = 3.3µF, SHDN > VIH, TA = 25°C, unless otherwise specified. BOLDFACE type specifications apply for junction temperatures of – 40°C to +125°C. Symbol VIN IOUTMAX VOUT Parameter Input Operating Voltage Maximum Output Current Output Voltage Test Conditions Min Typ — — VR ±0.5% Max 6.5 — VR + 2.5% Units V mA V — 50 VREF ≤ VOUT ≤ (VIN –0.05) VR – 2.5% IL = 0 (Note 1) — VREF ∆VREF/∆T ∆VOUT/∆VIN ∆VOUT/VOUT VIN – VOUT Reference Voltage VREF Temperature Coefficient Line Regulation Load Regulation Dropout Voltage (Note 4) IGND IIN IINSD PSRR IOUTSC ∆VOUT/∆PD TSD ∆TSD eN Ground Pin Current Supply Current Shutdown Supply Current Power Supply Rejection Ratio Output Short Circuit Current Thermal Regulation Thermal Shutdown Die Temperature Thermal Shutdown Hysteresis Output Noise Note 2 (VR + 1V) < VIN < 6V IL = 0.1mA to IOUTMAX (Note 3) IL = 0.1mA IL = 20mA IL = 50mA (Note 4) IL = IOUTMAX, (Note 5) SHDN = VIH, IL = 0 SHDN = 0V FRE ≤ 1kHz VOUT = 0V Note 6 — — — — 1.23 40 0.05 0.5 5 65 95 0 50 — 64 200 0.04 160 10 260 — — — — — V ppm/°C %/V % mV IL = IOUTMAX 470pF from Bypass to GND VIN = 2.5V to 6.5V VIN = 2.5V to 6.5V — — — — — — — — — — — 0.05 — 450 — — — — µA µA µA dB mA %/W °C °C nV/√Hz SHDN Input VIH VIL SHDN Input High Threshold SHDN Input Low Threshold 45 — — — — 15 %VIN %VIN TC1070-01 6/13/97 2 50mA ADJUSTABLE CMOS LDO WITH SHUTDOWN PRELIMINARY INFORMATION TC1070 ELECTRICAL CHARACTERISTICS: VIN = VOUT + 1V, IL = 0.1mA, CL = 3.3µF, SHDN > VIH, TA = 25°C, unless otherwise noted. Symbol ADJ Input IADJ Adjust Input Leakage Current — 50 — pA NOTES: 1. VR is the regulator output voltage setting. 2. TC VOUT = (VOUTMAX – VOUTMIN) x 106 VOUT x ∆T 3. Regulation is measured at a constant junction temperature using low duty cycle pulse testing. Load regulation is tested over a load range from 0.1mA to the maximum specified output current. Changes in output voltage due to heating effects are covered by the thermal regulation specification. 4. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value. 5. Ground pin current is the regulator pass transistor gate current. The total current drawn from the input supply is the sum of the load current, ground current and supply current (i.e. IIN = ISUPPLY + IGND + ILOAD). 6. Thermal Regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation effects. Specifications are for a current pulse equal to ILMAX at VIN = 6V for T = 10msec. 7. The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable junction temperature and the thermal resistance from junction-to-air (i.e. TA, TJ, qJA). Exceeding the maximum allowable power dissipation causes the device to initiate thermal shutdown. Please see Thermal Considerations section of this data sheet for more details. Parameter Test Conditions Min Typ Max Units PIN DESCRIPTION Pin No. (SOT-23A-5) 1 2 3 Symbol VIN GND SHDN Description Unregulated supply input. Ground terminal. Shutdown control input. The regulator is fully enabled when a logic high is applied to this input. The regulator enters shutdown when a logic low is applied to this input. During shutdown, output voltage falls to zero and supply current is reduced to 0.05 microamp (typical). Output voltage adjust terminal. Output voltage setting is programmed with a resistor divider from VOUT to this input. A capacitor may also be added to this input to resuce output noise (See Text). Regulated voltage output. 4 ADJ 5 VOUT TC1070-01 6/13/97 3 PRELIMINARY INFORMATION 50mA ADJUSTABLE CMOS LDO WITH SHUTDOWN TC1070 DETAILED DESCRIPTION The TC1070 is a precision fixed output voltage regulator. (If a fixed version is desired, please see the TC1014 or TC1015 data sheets.) Unlike the bipolar regulators, the TC1070 supply current does not increase with load current. In addition, VOUT remains stable and within regulation at very low load currents (an important consideration in RTC and CMOS RAM battery back-up applications). Figure 1 shows a typical application circuit. The regulator is enabled any time the shutdown input (SHDN) is at or above VIH, and shutdown (disabled) when SHDN is at or below VIL. SHDN may be controlled by a CMOS logic gate, or I/O port of a microcontroller. If the SHDN input is not required, it should be connected directly to the input supply. While in shutdown, supply current decreases to 0.05µA (typical) and VOUT falls to zero volts. Output Capacitor A 1µF (min) capacitor from VOUT to ground is recommended. The output capacitor should have an effective series resistance of 5Ω or less, and a resonant frequency above 1MHz. A 1µF capacitor should be connected from VIN to GND if there is more than 10 inches of wire between the regulator and the AC filter capacitor, or if a battery is used as the power source. Aluminum electrolytic or tantalum capacitor types can be used. (Since many aluminum electrolytic capacitors freeze at approximately – 30°C, solid tantalums are recommended for applications operating below – 25°C.) When operating from sources other than batteries, supplynoise rejection and transient response can be improved by increasing the value of the input and output capacitors and employing passive filtering techniques. Thermal Considerations 1 C1 1µF VIN VOUT 5 C2 1µF +2.45V 3.0V BATTERY 2 Thermal Shutdown Integrated thermal protection circuitry shuts the regulator off when die temperature exceeds 160°C. The regulator remains off until the die temperature drops to approximately 150°C. Power Dissipation The amount of power the regulator dissipates is primarily a function of input and output voltage, and output current. The following equation is used to calculate worst case actual power dissipation: PD ≈ (VINMAX – VOUTMIN)ILOADMAX Where: PD VINMAX VOUTMIN ILOADMAX = Worst case actual power dissipation = Maximum voltage on VIN = Minimum regulator output voltage = Maximum output (load) current Equation 2. GND TC1070 R1 2.2M 3 SHDN ADJ 4 C3 100pF 0.01µF (Optional) Shutdown Control (from Power Control Logic) R2 2.2M Figure 1. 2.45 Battery-Operated Supply Adjust Input The output voltage setting is determined by the values of R1 and R2 (Figure 1). The ohmic values of these resistors should be between 470K and 3M to minimize bleeder current. The output voltage setting is calculated using the following equation. VOUT = VREF x R1 + 1 R2 [ ] The maximum allowable power dissipation (Equation 2) is a function of the maximum ambient temperature (TAMAX), the maximum allowable die temperature (125°C) and the thermal resistance from junction-to-air (θJA). SOT-23A-5 packag has a θJA of approximately 220°C/Watt when mounted on a single layer FR4 dielectric copper clad PC board. PD MAX = (TJMAX – TJMAX) θJA Where all terms are previously defined. Equation 3. 4 Equation 1. The voltage adjustment range of the TC1070 is from VREF to (VIN – 0.05V). If so desired, a small capacitor (100pF to 0.01µF) may be added to the ADJ input to further reduce output noise. TC1070-01 6/13/97 50mA ADJUSTABLE CMOS LDO WITH SHUTDOWN PRELIMINARY INFORMATION TC1070 Equation 2 can be used in conjunction with Equation 3 to ensure regulator thermal operation is within limits. For example: Given: VINMAX = 3.0V ±10% VOUTMIN = 2.7V ±0.5V ILOAD = 40mA TAMAX = 55°C 1. Actual power dissipation 2. Maximum allowable dissipation Find: Actual power dissipation: PD ≈ (VINMAX – VOUTMIN)ILOADMAX = [(3.0 x 1.05) – (2.7 x .995)]40 x 10–3 = 18.5mW Maximum allowable power dissipation: PDMAX = (TJMAX – TAMAX) θJA = (125 – 55) 220 = 318mW In this example, the TC1070 dissipates a maximum of only 60mW; far below the allowable limit of 318mW. In a similar manner, Equation 2 and Equation 3 can be used to calculate maximum current and/or input voltage limits. Layout Considerations The primary path of heat conduction out of the package is via the package leads. Therefore, layouts having a ground plane, wide traces at the pads, and wide power supply bus lines combine to lower θJA and therefore increase the maximum allowable power dissipation limit. TC1070-01 6/13/97 5 PRELIMINARY INFORMATION 50mA ADJUSTABLE CMOS LDO WITH SHUTDOWN TC1070 SOT-23A-5 & = part number code + temperature range and voltage TC1070 (V) Adjustable Code BA represents year and quarter code represents lot ID number PACKAGE DIMENSIONS SOT-23A-5* .122 (3.10) .098 (2.50) .020 (0.50) .012 (0.30) .071 (1.80) .059 (1.50) .037 (0.95) REFERENCE .122 (3.10) .106 (2.70) .057 (1.45) .035 (0.90) .006 (0.15) .000 (0.00) 10° MAX. .022 (0.55) .008 (0.20) .010 (0.25) .004 (0.09) NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A) Dimensions: inches (mm) Sales Offices TelCom Semiconductor 1300 Terra Bella Avenue P.O. Box 7267 Mountain View, CA 94039-7267 TEL: 415-968-9241 FAX: 415-967-1590 E-Mail: liter@c2smtp.telcom-semi.com TC1070-01 6/13/97 TelCom Semiconductor Austin Product Center 9101 Burnet Rd. Suite 214 Austin, TX 78758 TEL: 512-873-7100 FAX: 512-873-8236 TelCom 6 TelCom Semiconductor H.K. Ltd. 10 Sam Chuk Street, 6/F San Po Kong Kowloon Hong Kong TEL: 852-2324-0122 FAX: 852-2354-9957 Printed in the U.S.A. 100mA ADJUSTABLE CMOS LDO WITH SHUTDOWN PRELIMINARY INFORMATION TC1071 TC1071 100mA ADJUSTABLE CMOS LDO WITH SHUTDOWN FEATURES s s s s s s s s Zero Ground Current for Longer Battery Life! Adjustable Output Voltage Very Low Dropout Voltage Guaranteed 100mA Output Power-Saving Shutdown Mode Over-Current and Over-Temperature Protection Space-Saving SOT-23A-5 Package Pin Compatible with LP2980 and MIC5205 Regulators GENERAL DESCRIPTION The TC1071 is an adjustable LDO designed to supercede a variety of older (bipolar) voltage regulators. Designed specifically for battery-operated systems, the TC1070’s CMOS construction eliminates wasted ground current, significantly extending battery life. Total supply current is typically 50µA at full load (20 to 60 times lower than in bipolar regulators!). TC1071 key features include ultra low noise operation very low dropout voltage (typically 200mV at full load) and internal feed-forward compensation for fast response to step changes in load. Supply current is reduced to less than 1µA when the shutdown input is low. The TC1071 incorporates both over-temperature and over-current protection. Output voltage is programmed with a simple resistor divider from VOUT to ADJ. The TC1071 is stable with an output capacitor of only 1µF and has a maximum output current of 100mA. For higher output versions, please see the TC1174 (IOUT = 300mA) data sheet. APPLICATIONS s s s s s s s Battery Operated Systems Portable Computers Medical Instruments Instrumentation Cellular / GSM / PHS Phones Linear Post-Regulator for SMPS Pagers TYPICAL APPLICATION ORDERING INFORMATION Part No. TC1071VCT Output Voltage **(V) Package Adjustable Junction Temp. Range VIN 1 SOT-23A-5* – 40°C to +125°C VIN VOUT 5 C1 1µF VOUT NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A) **Other output voltages available. Please contact TelCom Semiconductor for details 2 GND TC1071 R1 PIN CONFIGURATION VOUT ADJ 4 3 SHDN ADJ 4 5 R2 TC1071 (SOT-23A-5*) 1 2 3 TOP VIEW Shutdown Control (from Power Control Logic) VOUT = VREF x [ R2 + 1 R1 ] VIN GND SHDN NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A) TC1071-01 6/13/97 1 TelCom Semiconductor reserves the right to make changes in the circuitry and specifications ot its devices. PRELIMINARY INFORMATION 100mA ADJUSTABLE CMOS LDO WITH SHUTDOWN TC1071 ABSOLUTE MAXIMUM RATINGS* Input Voltage .................................................................7V Output Voltage .................................. (– 0.3) to (VIN + 0.3) Power Dissipation .................... Internally Limited (Note 7) Operating Temperature .................... – 40°C < TJ < 125°C Storage Temperature ............................ – 65°C to +150°C Maximum Voltage on Any Pin ........... VIN + 0.3V to – 0.3V Lead Temperature (Soldering, 10 Sec.) ................ +260°C *Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS: VIN = VOUT + 1V, IL = 0.1mA, CL = 3.3µF, SHDN > VIH, TA = 25°C, unless otherwise specified.BOLDFACE type specifications apply for junction temperatures of – 40°C to +125°C. Symbol VIN IOUTMAX VOUT Parameter Input Operating Voltage Maximum Output Current Output Voltage Test Conditions Min Typ — — VR ±0.5% Max 6.5 — VR + 2.5% Units V mA V — 100 VREF ≤ VOUT ≤ (VIN –0.05) VR – 2.5% IL = 0 (Note 1) — VREF ∆VREF/∆T ∆VOUT/∆VIN ∆VOUT/VOUT VIN – VOUT Reference Voltage VREF Temperature Coefficient Line Regulation Load Regulation Dropout Voltage (Note 4) IGND IIN IINSD PSRR IOUTSC ∆VOUT/∆PD eN Ground Pin Current Supply Current Shutdown Supply Current Power Supply Rejection Ratio Output Short Circuit Current Thermal Regulation Output Noise Note 2 (VR + 1V) < VIN < 6V IL = 0.1mA to IOUTMAX (Note 3) IL = 0.1mA IL = 20mA IL = 50mA IL = 100mA (Note 4) IL = IOUTMAX, (Note 5) SHDN = VIH, IL = 0 SHDN = 0V FRE ≤ 1kHz VOUT = 0V Note 6 IL = IOUTMAX 470pF from Bypass to GND VIN = 2.5V to 6.5V VIN = 2.5V to 6.5V — — — — 1.23 40 0.05 0.5 20 70 93 112 0 50 — 64 300 0.04 260 — — — — — V %/V % mV — — — — — — — — — 0.05 — 450 — — µA µA µA dB mA %/W nV/√Hz SHDN Input VIH VIL SHDN Input High Threshold SHDN Input Low Threshold 45 — — — — 15 %VIN %VIN TC1071-01 6/13/97 2 100mA ADJUSTABLE CMOS LDO WITH SHUTDOWN PRELIMINARY INFORMATION TC1071 ELECTRICAL CHARACTERISTICS: VIN = VOUT + 1V, IL = 0.1mA, CL = 3.3µF, SHDN > VIH, TA = 25°C, unless otherwise noted. Symbol ADJ Input IADJ Adjust Input Leakage Current — 50 — pA NOTES: 1. VR is the regulator output voltage setting. 2. TC VOUT = (VOUTMAX – VOUTMIN) x 106 VOUT x ∆T 3. Regulation is measured at a constant junction temperature using low duty cycle pulse testing. Load regulation is tested over a load range from 0.1mA to the maximum specified output current. Changes in output voltage due to heating effects are covered by the thermal regulation specification. 4. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value. 5. Ground pin current is the regulator pass transistor gate current. The total current drawn from the input supply is the sum of the load current, ground current and supply current (i.e. IIN = ISUPPLY + IGND + ILOAD). 6. Thermal Regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation effects. Specifications are for a current pulse equal to ILMAX at VIN = 6V for T = 10msec. 7. The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable junction temperature and the thermal resistance from junction-to-air (i.e. TA, TJ, qJA). Exceeding the maximum allowable power dissipation causes the device to initiate thermal shutdown. Please see Thermal Considerations section of this data sheet for more details. Parameter Test Conditions Min Typ Max Units PIN DESCRIPTION Pin No. (SOT-23A-5) 1 2 3 Symbol VIN GND SHDN Description Unregulated supply input. Ground terminal. Shutdown control input. The regulator is fully enabled when a logic high is applied to this input. The regulator enters shutdown when a logic low is applied to this input. During shutdown, output voltage falls to zero and supply current is reduced to 0.05 microamp (typical). Output voltage adjust terminal. Output voltage setting is programmed with a resistor divider from VOUT to this input. A capacitor may also be added to this input to resuce output noise (See Text). Regulated voltage output. 4 ADJ 5 VOUT TC1071-01 6/13/97 3 PRELIMINARY INFORMATION 100mA ADJUSTABLE CMOS LDO WITH SHUTDOWN TC1071 DETAILED DESCRIPTION The TC1071 is a precision fixed output voltage regulator. (If a fixed version is desired, please see the TC1014 or TC1015 data sheets.) Unlike the bipolar regulators, the TC1071 supply current does not increase with load current. In addition, VOUT remains stable and within regulation at very low load currents (an important consideration in RTC and CMOS RAM battery back-up applications). Figure 1 shows a typical application circuit. The regulator is enabled any time the shutdown input (SHDN) is at or above VIH, and shutdown (disabled) when SHDN is at or below VIL. SHDN may be controlled by a CMOS logic gate, or I/O port of a microcontroller. If the SHDN input is not required, it should be connected directly to the input supply. While in shutdown, supply current decreases to 0.05µA (typical) and VOUT falls to zero volts. Output Capacitor A 1µF (min) capacitor from VOUT to ground is recommended. The output capacitor should have an effective series resistance of 5Ω or less, and a resonant frequency above 1MHz. A 1µF capacitor should be connected from VIN to GND if there is more than 10 inches of wire between the regulator and the AC filter capacitor, or if a battery is used as the power source. Aluminum electrolytic or tantalum capacitor types can be used. (Since many aluminum electrolytic capacitors freeze at approximately – 30°C, solid tantalums are recommended for applications operating below – 25°C.) When operating from sources other than batteries, supplynoise rejection and transient response can be improved by increasing the value of the input and output capacitors and employing passive filtering techniques. Thermal Considerations 1 C1 1µF VIN VOUT 5 C2 1µF +2.45V 3.0V BATTERY 2 Thermal Shutdown Integrated thermal protection circuitry shuts the regulator off when die temperature exceeds 160°C. The regulator remains off until the die temperature drops to approximately 150°C. Power Dissipation The amount of power the regulator dissipates is primarily a function of input and output voltage, and output current. The following equation is used to calculate worst case actual power dissipation: PD ≈ (VINMAX – VOUTMIN)ILOADMAX Where: PD VINMAX VOUTMIN ILOADMAX = Worst case actual power dissipation = Maximum voltage on VIN = Minimum regulator output voltage = Maximum output (load) current Equation 2. GND TC1071 R1 2.2M 3 SHDN ADJ 4 R2 2.2M Shutdown Control (from Power Control Logic) Figure 1. 2.45 Battery-Operated Supply Adjust Input The output voltage setting is determined by the values of R1 and R2 (Figure 1). The ohmic values of these resistors should be between 470K and 3M to minimize bleeder current. The output voltage setting is calculated using the following equation. VOUT = VREF x R1 + 1 R2 [ ] The maximum allowable power dissipation (Equation 3) is a function of the maximum ambient temperature (TAMAX), the maximum allowable die temperature (125°C) and the thermal resistance from junction-to-air (θJA). SOT-23A-5 package has a θJA of approximately 220°C/Watt when mounted on a single layer FR4 dielectric copper clad PC board. PD MAX = (TJMAX – TAMAX) θJA Where all terms are previously defined. Equation 3. 4 Equation 1. The voltage adjustment range of the TC1071 is from VREF to (VIN – 0.05V). If so desired, a small capacitor (100pF to 0.01µF) may be added to the ADJ input to further reduce output noise. TC1071-01 6/13/97 100mA ADJUSTABLE CMOS LDO WITH SHUTDOWN PRELIMINARY INFORMATION TC1071 Equation 2 can be used in conjunction with Equation 3 to ensure regulator thermal operation is within limits. For example: Given: VINMAX = 3.0V ±10% VOUTMIN = 2.7V ±0.5V ILOAD = 98mA TAMAX = 55°C 1. Actual power dissipation 2. Maximum allowable dissipation Find: Actual power dissipation: PD ≈ (VINMAX – VOUTMIN)ILOADMAX = [(3.0 x 1.1) – (2.7 x .995)]40 x 10–3 = 60mW Maximum allowable power dissipation: PDMAX = (TJMAX – TAMAX) θJA = (125 – 55) 220 = 318mW In this example, the TC1071 dissipates a maximum of only 60mW; far below the allowable limit of 318mW. In a similar manner, Equation 1 and Equation 2 can be used to calculate maximum current and/or input voltage limits. For example, the maximum allowable VIN is found by substituting the maximum allowable power dissipation of 318mW into Equation 1, from which VINMAX = 5.9V. Layout Considerations The primary path of heat conduction out of the package is via the package leads. Therefore, layouts having a ground plane, wide traces at the pads, and wide power supply bus lines combine to lower θJA and therefore increase the maximum allowable power dissipation limit. TC1071-01 6/13/97 5 PRELIMINARY INFORMATION 100mA ADJUSTABLE CMOS LDO WITH SHUTDOWN TC1071 SOT-23A-5 & = part number code + temperature range and voltage TC1071 (V) Adjustable Code BB represents year and quarter code represents lot ID number PACKAGE DIMENSIONS SOT-23A-5* .122 (3.10) .098 (2.50) .020 (0.50) .012 (0.30) .071 (1.80) .059 (1.50) .037 (0.95) REFERENCE .122 (3.10) .106 (2.70) .057 (1.45) .035 (0.90) .006 (0.15) .000 (0.00) 10° MAX. .022 (0.55) .008 (0.20) .010 (0.25) .004 (0.09) NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A) Dimensions: inches (mm) Sales Offices TelCom Semiconductor 1300 Terra Bella Avenue P.O. Box 7267 Mountain View, CA 94039-7267 TEL: 415-968-9241 FAX: 415-967-1590 E-Mail: liter@c2smtp.telcom-semi.com TelCom Semiconductor Austin Product Center 9101 Burnet Rd. Suite 214 Austin, TX 78758 TEL: 512-873-7100 FAX: 512-873-8236 TelCom TelCom Semiconductor H.K. Ltd. 10 Sam Chuk Street, 6/F San Po Kong Kowloon Hong Kong TEL: 852-2324-0122 FAX: 852-2354-9957 TC1071-01 6/13/97 6 Printed in the U.S.A.