TL497AC, TL497AI, TL497AY SWITCHING VOLTAGE REGULATORS SLVS009C – JUNE 1976 – REVISED AUGUST 1995 • • • • • • • • TL497AC, TL497AI . . . D, N, OR PW PACKAGE (TOP VIEW) High Efficiency . . . 60% or Greater Output Current . . . 500 mA COMP INPUT INHIBIT FREQ CONTROL SUBSTRATE GND CATHODE ANODE Input Current Limit Protection TTL-Compatible Inhibit Adjustable Output Voltage Input Regulation . . . 0.2% Typ Output Regulation . . . 0.4% Typ 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 are not normally used in circuit applications of the device. Soft Start-Up Capability description The TL497AC and TL497AI incorporate on a single monolithic chip all the active functions required in the construction of switching voltage regulators. They can also be used as the control element to drive external components for high-power-output applications. The TL497AC and TL497AI were designed for ease of use in step-up, step-down, or voltage inversion applications requiring high efficiency. The TL497AC and TL497AI are fixed-on-time variable-frequency switching-voltage-regulator control circuits. 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 may 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 is also available for blocking or commutating purposes. The TL497AC and TL497AI also have 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. AVAILABLE OPTIONS PACKAGED DEVICES TA SURFACE MOUNT (D) PLASTIC DIP (N) SHRINK SMALL OUTLINE (PW) CHIP FORM (Y) 0°C to 70°C TL497ACD TL497ACN TL497ACPW TL497AY – 40°C to 85°C TL497AID TL497AIN — — Copyright 1995, 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 4–1 TL497AC, TL497AI, TL497AY SWITCHING VOLTAGE REGULATORS SLVS009C – JUNE 1976 – REVISED AUGUST 1995 description (continued) Simplicity of design is a primary feature of the TL497AC and TL497AI. With only six external components (three resistors, two capacitors, and one inductor), the TL497AC and TL497AI 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 TL497AC and TL497AI replace the TL497 in all applications. The TL497AC is characterized for operation from 0°C to 70°C, and the TL497AI is characterized for operation from – 40°C to 85°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 COL OUT EMIT OUT ANODE † BASE and BASE DRIVE are used for device testing only. They are not normally used in circuit applications of the device. 4–2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TL497AC, TL497AI, TL497AY SWITCHING VOLTAGE REGULATORS SLVS009C – JUNE 1976 – REVISED AUGUST 1995 TL497AY chip information This chip, when properly assembled, displays characteristics similar to the TL497AC. Thermal compression or ultrasonic bonding may be used on the doped aluminum bonding pads. The chips may be mounted with conductive epoxy or a gold-silicon preform. BONDING PAD ASSIGNMENTS (13) (11) (12) (10) (8) (14) CHIP THICKNESS: 15 MILS TYPICAL BONDING PADS: 4 × 4 MILS MINIMUM 68 TJmax= 150°C TOLERANCES ARE ± 10% ALL DIMENSIONS ARE IN MILS (1) (2) (3) (4) (5) (7) (6) 115 CUR BASE LIM SENS DRIVE† BASE† (13) FREQ CONTROL (12) (11) (3) (2) INHIBIT (1) COMP INPUT (4) SUBSTRATE (6) CATHODE (10) COL OUT (8) EMIT TL497AY OUT (7) (5) GND ANODE (14) VCC † BASE (11) and BASE DRIVE (12) are used for device testing only. They are not normally used in circuit applications of the device. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 4–3 TL497AC, TL497AI, TL497AY SWITCHING VOLTAGE REGULATORS SLVS009C – JUNE 1976 – REVISED AUGUST 1995 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 Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Dissipation Rating Table Operating free-air temperature range, TA: TL497AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C TL497AI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 40°C to 85°C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C Lead temperature 1,6 mm (1/16 inch) from case for 60 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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 under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. NOTE 1: All voltage values except diode voltages are with respect to network ground terminal. DISSIPATION RATING TABLE TA ≤ 25°C POWER RATING DERATING FACTOR D 950 mW N 1000 mW PW 700 mW PACKAGE TA = 70°C POWER RATING TA = 85°C POWER RATING 7.6 mW/°C DERATE ABOVE TA 25°C 608 mW 494 mW 9.2 mW/°C 41°C 733 mW 595 mW 5.6 mW/°C 25°C 448 mW — recommended operating conditions MIN MAX Supply voltage, VCC 4.5 12 High-level input voltage, VIH, INHIBIT 2.5 Low-level input voltage, VIL, INHIBIT O p voltage Output l g Step-down configuration (see Figure 2) VI + 2 Vref Inverting regulator (see Figure 3) –Vref V V 0.8 Step-up configuration (see Figure 1) UNIT V 30 VI – 1 – 25 V Power switch current 500 mA Diode forward current 500 mA 0 70 – 40 85 °C Operating free-air temperature, temperature TA 4–4 TL497AC TL497AI POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TL497AC, TL497AI, TL497AY SWITCHING VOLTAGE REGULATORS SLVS009C – JUNE 1976 – REVISED AUGUST 1995 electrical characteristics over recommended operating conditions, VCC = 6 V (unless otherwise noted) PARAMETER TEST CONDITIONS High-level input current, INHIBIT Low-level input current, INHIBIT Comparator reference voltage Comparator input bias current TL497AC TYP‡ MAX 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-state voltage VI = 4 4.5 5V Switch off-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 MIN VI(I) = 5 V VI(I) = 0 V IO = 100 mA IO = 500 mA Di d fforward Diode d voltage l g TA† 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 30 Full range 11 Full range 11 15 25°C Off-state supply current 14 6 Full range 14 16 9 µA V V V 30 25°C On-state supply current V 6 10 9 11 mA mA † Full range for the TL497AC is 0°C to 70°C and full range for the TL497AI is – 40°C to 85°C. ‡ 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 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 Di d fforward d voltage l g 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 4–5 TL497AC, TL497AI, TL497AY SWITCHING VOLTAGE REGULATORS SLVS009C – JUNE 1976 – REVISED AUGUST 1995 APPLICATION INFORMATION L RCL VO VI 14 13 10 8 R1 TL497A I (PK) + 2 IO max CO L (mH) 1 2 3 4 5 6 7 +I R2 = 1.2 kΩ V I (PK) C (pF) T BASIC CONFIGURATION (Peak Switching Current = I(PK) < 500 mA) RCL L VO [ 12 ton (ms) + (VO * 1.2) kW V R + 0.5 CL I (PK) 13 10 R1 8 CO TL497A 2 3 4 5 C O (mF) [ ton(ms) R2 = 1.2 kΩ CT EXTENDED POWER CONFIGURATION (using external transistor) Figure 1. Positive Regulator, Step-Up Configurations 4–6 O V I t on (ms) R1 VI 1 V Choose L (50 to 500 µH), calculate ton (25 to 150 µs) CT 14 ƪƫ DESIGN EQUATIONS POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 ƪ V V I O V I (PK) ripple ) IO (PK) ƫ TL497AC, TL497AI, TL497AY SWITCHING VOLTAGE REGULATORS SLVS009C – JUNE 1976 – REVISED AUGUST 1995 APPLICATION INFORMATION RCL L VO VI 14 13 10 DESIGN EQUATIONS 8 R1 TL497A 1 2 3 I CO 4 5 6 7 (PK) + 2 IO max L (mH) R2 = 1.2 kΩ V – V I O t on(ms) I (PK) Choose L (50 to 500 µH), calculate ton (10 to 150 µs) CT C (pF) T BASIC CONFIGURATION (Peak Switching Current = I(PK) < 500 mA) RCL + [ 12 ton(ms) + (VO * 1.2) kW V R + 0.5 CL I R1 L VO VI (PK) C 14 13 10 8 2 3 4 (mF) [ ton(ms) V I * VO V O V I (PK) ripple ) IO (PK) ƫ R1 TL497A 1 O ƪ CO 5 6 7 R2 = 1.2 kΩ CT EXTENDED POWER CONFIGURATION (using external transistor) Figure 2. Positive Regulator, Step-Down Configurations POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 4–7 TL497AC, TL497AI, TL497AY SWITCHING VOLTAGE REGULATORS SLVS009C – JUNE 1976 – REVISED AUGUST 1995 APPLICATION INFORMATION RCL DESIGN EQUATIONS 14 13 10 8 R1 † I 1 2 3 4 (PK) + 2 IO max 1 ) CO TL497A L (mH) R2 = 1.2 kΩ 5 VO CT BASIC CONFIGURATION (Peak Switching Current = I(PK) < 500 mA) RCL +I V I (PK) L [ 12 ton(ms) ǒŤ Ť Ǔ W (PK) C 13 10 8 R1 † TL497A 1 2 3 4 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 O V I t on(ms) + VO – 1.2 V R + 0.5 CL I R1 VI 14 V Choose L (50 to 500 µH), calculate ton (10 to 150 µs) C (pF) T 4–8 ƪ Ť Ťƫ L VI O (mF) [ ton(ms) ƪŤ Ť ƫ k V V I I (PK) ) IO O V ripple (PK) TL497AC, TL497AI, TL497AY SWITCHING VOLTAGE REGULATORS SLVS009C – JUNE 1976 – REVISED AUGUST 1995 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 V Vreg 3-Term Reg < 12 V 10 mA R CL 1 kΩ R1 Control R2 14 13 R2 + I BE(Q1) limit (PK) )I + V I B(Q2) ǒ V reg Ǔ *1 10 kW TL497A R1 5 Q2 CURRENT LIMIT FOR EXTENDED INPUT CONFIGURATION Figure 4. Extended Input Voltage Range (VI > 12 V) POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 4–9 4–10 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 IMPORTANT NOTICE Texas Instruments (TI) reserves the right to make changes to its products or to discontinue any semiconductor product or service without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing orders, that the information being relied on is current. TI warrants performance of its semiconductor products and related software 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, INTENDED, AUTHORIZED, OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT APPLICATIONS, DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. Inclusion of TI products in such applications is understood to be fully at the risk of the customer. Use of TI products in such applications requires the written approval of an appropriate TI officer. Questions concerning potential risk applications should be directed to TI through a local SC sales office. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards should be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or services described herein. Nor does TI 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. Copyright 1995, Texas Instruments Incorporated