TL497A SWITCHING VOLTAGE REGULATORS SLVS009D – JUNE 1976 – REVISED JULY 1999 D D D D D D D D D, N, OR PW PACKAGE (TOP VIEW) High Efficiency . . . 60% or Greater Output Current . . . 500 mA Input Current Limit Protection TTL-Compatible Inhibit Adjustable Output Voltage Input Regulation . . . 0.2% Typ Output Regulation . . . 0.4% Typ Soft Start-Up Capability COMP INPUT INHIBIT FREQ CONTROL SUBSTRATE GND CATHODE ANODE description 1 14 2 13 3 12 4 11 5 10 6 9 7 8 VCC CUR LIM SENS BASE DRIVE† BASE† COL OUT NC EMIT OUT NC – No internal connection † BASE (11) and BASE DRIVE (12) are used for device testing only. They normally are not used in circuit applications of the device. The TL497A incorporates all the active functions required in the construction of switching voltage regulators. It can also be used as the control element to drive external components for high-power-output applications. The TL497A was designed for ease of use in step-up, step-down, or voltage-inversion applications requiring high efficiency. The TL497A is a fixed-on-time variable-frequency switching-voltage-regulator control circuit. The switch-on time is programmed by a single external capacitor connected between FREQ CONTROL and GND. This capacitor, CT, is charged by an internal constant-current generator to a predetermined threshold. The charging current and the threshold vary proportionally with VCC. Thus, the switch-on time remains constant over the specified range of input voltage (4.5 V to 12 V). Typical on times for various values of CT are as follows: TIMING CAPACITOR, CT (pF) ON TIME (µs) 200 250 350 400 500 750 1000 1500 2000 19 22 26 32 44 56 80 120 180 The output voltage is controlled by an external resistor ladder network (R1 and R2 in Figures 1, 2, and 3) that provides a feedback voltage to the comparator input. This feedback voltage is compared to the reference voltage of 1.2 V (relative to SUBSTRATE) by the high-gain comparator. When the output voltage decays below the value required to maintain 1.2 V at the comparator input, the comparator enables the oscillator circuit, which charges and discharges CT as described above. The internal pass transistor is driven on during the charging of CT. The internal transistor can be used directly for switching currents up to 500 mA. Its collector and emitter are uncommitted, and it is current driven to allow operation from the positive supply voltage or ground. An internal Schottky diode matched to the current characteristics of the internal transistor also is available for blocking or commutating purposes. The TL497A also has on-chip current-limit circuitry that senses the peak currents in the switching regulator and protects the inductor against saturation and the pass transistor against overstress. The current limit is adjustable and is programmed by a single sense resistor, RCL, connected between VCC and CUR LIM SENS. The current-limit circuitry is activated when 0.7 V is developed across RCL. External gating is provided by the INHIBIT input. When the INHIBIT input is high, the output is turned off. Simplicity of design is a primary feature of the TL497A. With only six external components (three resistors, two capacitors, and one inductor), the TL497A operates in numerous voltage-conversion applications (step-up, step-down, invert) with as much as 85% of the source power delivered to the load. The TL497A replaces the TL497 in all applications. The TL497AC is characterized for operation from 0°C to 70°C. The TL497AI is characterized for operation from –40°C to 85°C. Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Copyright 1999, Texas Instruments Incorporated PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1 TL497A SWITCHING VOLTAGE REGULATORS SLVS009D – JUNE 1976 – REVISED JULY 1999 AVAILABLE OPTIONS PACKAGED DEVICES CHIP FORM (Y) TA SMALL-OUTLINE (D) PLASTIC DIP (N) SHRINK SMALL-OUTLINE (PW) 0°C to 70°C TL497ACD TL497ACN TL497ACPW TL497AY –40°C to 85°C TL497AID TL497AIN — — The D and PW packages are only taped and reeled. Add the suffix R to the device type (e.g., TL497ACPWR). Chip forms are tested at 25°C. functional block diagram BASE† BASE DRIVE† CUR LIM SENS FREQ CONTROL INHIBIT COMP INPUT SUBSTRATE CATHODE 11 12 13 Current Limit Sense 3 2 Oscillator 1 4 10 1.2-V Reference 8 6 7 † BASE and BASE DRIVE are used for device testing only. They normally are not used in circuit applications of the device. 2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 COL OUT EMIT OUT ANODE TL497A SWITCHING VOLTAGE REGULATORS SLVS009D – JUNE 1976 – REVISED JULY 1999 absolute maximum ratings over operating free-air temperature range (unless otherwise noted)† Supply voltage, VCC (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 V Output voltage, VO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 V Input voltage, VI(COMP INPUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 V Input voltage, VI(INHIBIT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 V Diode reverse voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 V Power switch current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750 mA Diode forward current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750 mA Package thermal impedance, θJA (see Notes 2 and 3): D package . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86°C/W N package . . . . . . . . . . . . . . . . . . . . . . . . . . . 101°C/W PW package . . . . . . . . . . . . . . . . . . . . . . . . . . 113°C/W Lead temperature 1,6 mm (1/16 inch) from case for 60 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°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 under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. NOTES: 1. All voltage values except diode voltages are with respect to network ground terminal. 2. Maximum power dissipation is a function of TJ(max), θJA, and TA. The maximum allowable power dissipation at any allowable ambient temperature is PD = (TJ(max) – TA)/θJA. Operating at the absolute maximum TJ of 150°C can impact reliability. 3. The package thermal impedance is calculated in accordance with JESD 51, except for through-hole packages, which use a trace length of zero. recommended operating conditions Supply voltage, VCC High-level input voltage, VIH INHIBIT pin Low-level input voltage, VIL INHIBIT pin MAX 4.5 12 2.5 Step-down configuration (see Figure 2) VI + 2 Vref Inverting regulator (see Figure 3) –Vref UNIT V V 0.8 Step-up configuration (see Figure 1) Output voltage MIN V 30 VI – 1 –25 V Power switch current 500 mA Diode forward current 500 mA 0 70 –40 85 °C TL497AC Operating temperature range TA O erating free-air tem erature range, TL497AI POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 3 TL497A SWITCHING VOLTAGE REGULATORS SLVS009D – JUNE 1976 – REVISED JULY 1999 electrical characteristics over recommended operating conditions, VCC = 6 V (unless otherwise noted) PARAMETER TA† TEST CONDITIONS High-level input current, INHIBIT Low-level input current, INHIBIT Comparator reference voltage Comparator input bias current MIN TL497AI TYP‡ MAX UNIT Full range 0.8 1.5 0.8 1.5 mA Full range 5 10 5 20 µA VI = 4.5 V to 6 V VI = 6 V Full range 1.2 1.32 1.2 1.26 V 40 100 40 100 µA 0.13 0.2 0.13 0.2 Switch on on-state state voltage VI = 4 4.5 5V Switch off off-state state current VI = 4 4.5 5V V, VO = 30 V Sense voltage, CUR LIM SENS VI = 6 V IO = 10 mA Diode reverse voltage TL497AC TYP‡ MAX VI(I) = 5 V VI(I) = 0 V IO = 100 mA IO = 500 mA Diode forward voltage MIN 1.08 Full range 25°C Full range 0.85 25°C 10 Full range 25°C 1.14 1 50 10 200 0.45 1 50 500 0.45 1 Full range 0.75 0.85 0.75 0.95 IO = 100 mA IO = 500 mA Full range 0.9 1 0.9 1.1 Full range 1.33 1.55 1.33 1.75 IO = 500 µA IO = 200 µA Full range Full range 30 11 Full range 25°C Off state supply current Off-state 14 11 15 6 Full range 14 16 9 µA V V V 30 25°C On state supply current On-state V 6 10 9 11 mA mA † Full range is 0°C to 70°C for the TL497AC and –40°C to 85°C for the TL497AI. ‡ All typical values are at TA = 25°C. electrical characteristics over recommended operating conditions, VCC = 6 V, TA = 25°C (unless otherwise noted) PARAMETER TEST CONDITIONS High-level input current, INHIBIT Low-level input current, INHIBIT Comparator reference voltage Comparator input bias current Switch on-state voltage 4 TL497AY MIN TYP MAX UNIT VI(I) = 5 V VI(I) = 0 V 0.8 mA 5 µA VI = 4.5 V to 6 V VI = 6 V 1.2 V 40 µA Switch off-state current VI = 4.5 V, VI = 4.5 V, IO = 100 mA VO = 30 V 0.13 V 10 µA 0.75 Diode forward voltage IO = 10 mA IO = 100 mA IO = 500 mA 1.33 0.9 V On-state supply current 11 mA Off-state supply current 6 mA POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TL497A SWITCHING VOLTAGE REGULATORS SLVS009D – JUNE 1976 – REVISED JULY 1999 APPLICATION INFORMATION RCL L VO VI 14 13 10 8 R1 TL497A I + 2 IO max (PK) CO m L ( H) 1 2 3 4 5 6 7 ƪƫ DESIGN EQUATIONS + I VI (PK) R2 = 1.2 kΩ C (pF) T BASIC CONFIGURATION (Peak Switching Current = I(PK) < 500 mA) RCL L VO [ 12 ton (ms) + (VO – 1.2 V) kW V R + 0.5 CL I (PK) 13 10 R1 8 CO TL497A 2 3 m t on ( s) R1 VI 1 O V I Choose L (50 to 500 µH), calculate ton (25 to 150 µs) CT 14 V 4 5 C O m ( F) [ ton(ms) ƪ V V I I (PK) O V ripple ) IO (PK) ƫ R2 = 1.2 kΩ CT EXTENDED POWER CONFIGURATION (using external transistor) Figure 1. Positive Regulator, Step-Up Configurations POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 5 TL497A SWITCHING VOLTAGE REGULATORS SLVS009D – JUNE 1976 – REVISED JULY 1999 APPLICATION INFORMATION RCL L VO VI 14 13 10 DESIGN EQUATIONS 8 R1 TL497A I + 2 IO max (PK) CO m L ( H) 1 2 3 4 5 6 7 R2 = 1.2 kΩ V – V I O t on( s) I (PK) C (pF) T BASIC CONFIGURATION (Peak Switching Current = I(PK) < 500 mA) [ 12 ton(ms) + (VO – 1.2 V) kW V R + 0.5 CL I R1 L VO VI (PK) C 14 13 10 8 1 2 3 4 O m ( F) [ ton(ms) R1 TL497A CO 5 6 7 R2 = 1.2 kΩ CT EXTENDED POWER CONFIGURATION (using external transistor) Figure 2. Positive Regulator, Step-Down Configurations 6 POST OFFICE BOX 655303 m Choose L (50 to 500 µH), calculate ton (10 to 150 µs) CT RCL + • DALLAS, TEXAS 75265 ƪ V I * VO V O V I (PK) ripple ) IO (PK) ƫ TL497A SWITCHING VOLTAGE REGULATORS SLVS009D – JUNE 1976 – REVISED JULY 1999 APPLICATION INFORMATION ƪ Ť Ťƫ L RCL VI DESIGN EQUATIONS 14 13 10 8 R1 † I CO TL497A 1 2 3 4 + 2 IO max 1 ) (PK) m L ( H) R2 = 1.2 kΩ 5 VO CT (PK) BASIC CONFIGURATION (Peak Switching Current = I(PK) < 500 mA) L [ 12 ton(ms) ǒŤ Ť (PK) C 13 10 8 R1 2 3 4 ǓW ƪŤ Ť ƫ O m ( F) [ ton(ms) k V V I I (PK) ) IO O V ripple (PK) † TL497A 1 m t on( s) + VO – 1.2 V V R + 0.5 CL I R1 VI 14 O V I Choose L (50 to 500 µH), calculate ton (10 to 150 µs) C (pF) T RCL + I VI V CO 5 R2 = 1.2 kΩ VO CT EXTENDED POWER CONFIGURATION (using external transistor) † Use external catch diode, e.g., 1N4001, when building an inverting supply with the TL497A. Figure 3. Inverting Applications POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 7 TL497A SWITCHING VOLTAGE REGULATORS SLVS009D – JUNE 1976 – REVISED JULY 1999 APPLICATION INFORMATION Switching Circuit VI VO 3-Term Reg < 12 V Control 14 13 TL497A 5 EXTENDED INPUT CONFIGURATION WITHOUT CURRENT LIMIT RCL VI Switching Circuit VO DESIGN EQUATIONS Q1 Vreg 3-Term Reg < 12 V R CL 1 kΩ R1 Control R2 14 13 R2 TL497A R1 5 Q2 CURRENT LIMIT FOR EXTENDED INPUT CONFIGURATION Figure 4. Extended Input Voltage Range (VI > 12 V) 8 + I BE(Q1) V 10 mA POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 limit (PK) )I + V I B(Q2) ǒ V reg Ǔ *1 10 k W IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER’S RISK. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI’s publication of information regarding any third party’s products or services does not constitute TI’s approval, warranty or endorsement thereof. Copyright 1999, Texas Instruments Incorporated