TC38C46

TC18C46 TC28C46 TC38C46 CMOS CURRENT MODE PWM CONTROLLER FEATURES s s s s s s s s s s s s s s s s s s s Isolated Output Drive Low Power CMOS Construction Low Supply Current ................................. 2mA Typ. Wide Supply Voltage Operation .............. 8V to 18V Latch-Up Immunity ................... 500mA on Outputs Above and Below Rail Input Protection ............. 6V High Output Drive ................................ 500mA Peak Current Mode Control Fast Rise/Fall Time ..................... 50nsec @ 1000pF High Frequency Operation .......................... 500kHz UV Hysteresis Guaranteed Programmable Current Limit Shutdown Pin Available Double Ended Soft Start Low Prop Delay Current Amp to Output ......................................... < 350nsec Typ. Low Prop Delay Shutdown to Output ......................................... < 400nsec Typ. TC38C46Pin Compatible with Unitrode UC3846 ESD Protected ................................................. ±2 kV 1 GENERAL DESCRIPTION The TC38C46 is a current mode CMOS PWM control IC. It draws only 2 mA supply current, so it can be driven without a costly 50-60 Hz transformer. The output drive stage is capable of high drive currents, 300mA typical. The TC38C46 is pin compatible with earlier bipolar products so that designers can easily update older designs. A number of improvements have been added. This second generation part has been designed with an isolated drive stage. Unlike its cousin, the TC170, the output stage of the TC38C46 can be run from a separate power supply such as a secondary winding on an output transformer. This allows for bootstrap start-up of the power supply. 2 3 4 5 6 ORDERING INFORMATION Part No. TC18C46MJE TC28C46EOE TC28C46EPE TC38C46COE TC38C46CPE Configuration Non-Inverting Non-Inverting Non-Inverting Non-Inverting Non-Inverting Pkg./Temperature 16-Pin CerDIP – 55°C to +125°C 16-Pin SOIC (Wide) – 40 °C to +85°C 16-Pin Plastic DIP (Narrow) – 40°C to +85°C 16-Pin SOIC (Wide) 0°C to +70°C 16-Pin Plastic DIP (Narrow) 0°C to +70°C FUNCTIONAL BLOCK DIAGRAM VREF 2 VIN RT CT SYNC – CURRENT SENSE INPUT + CURRENT SENSE INPUT COMPENSATION 15 9 8 10 3 4 7 + +VS + ERROR AMP INPUT – ERROR AMP INPUT 5 6 + – ERROR AMPLIFIER 100µA LIMIT BUFFER AMPLIFIER Q4 + – 350mV LOCK-UP AMPLIFIER Q3 TC18C46 TC28C46 TC38C46 3.5kΩ Q1 – + POSITIVE FEEDBACK Q2 6kΩ SHUTDOWN COMPARATOR + – 350mV 16 CURRENT SENSE PWM AMPLIFIER COMPARATOR .65V – + x3 –+ + – R Q S S PWM LATCH 14 12 OSCILLATOR UNDER VOLTAGE LOCKOUT DQ CQ 5.1 VOLT REFERENCE 13 11 VDD OUTPUT A OUTPUT B GROUND 1 7 CURRENT LIMIT SOFT START ADJUST SHUTDOWN TC38C46 OUTPUTS LOW IN OFF STATE 8 TC18/28/28/C46-8 9/23/96 TELCOM SEMICONDUCTOR, INC. 4-101 CMOS CURRENT MODE PWM CONTROLLERS TC18C46 TC28C46 TC38C46 ABSOLUTE MAXIMUM RATINGS Output Current, Source or Sink (Pins 1, 14) ..........500mA Analog Inputs (Pins 3, 4, 5, 6, 16) .............. – 0.3V to +VIN Reference Output Current (Pin 2) ........................ – 30 mA Sync Output Current (Pin 10) .................................. – 5mA Error Amplifier Output Current (Pin 7) ..................... – 5mA Soft Start Sink Current (Pin 1) .................................. 50mA Oscillator Charging Current (Pin 9) ............................5mA Supply Voltage ............................................................18V Maximum Chip Temperature ................................... 150°C Storage Temperature ............................ – 65°C to +150°C Lead Temperature (Soldering, 10 sec) ................... 300°C Package Thermal Resistance CerDIP RθJ-A ................................................................. 150°C/W CerDIP RθJ-C ................................................................... 55°C/W PDIP RθJ-A ..................................................................... 125°C/W PDIP RθJ-C ........................................................................ 45°C/W SOIC RθJ-A ..................................................................... 250°C/W SOIC RθJ-C ....................................................................... 75°C/W NOTES: 1. All voltages are with respect to Ground, Pin 12. Currents are positive into, negative out of the specified terminal. 2. Static-sensitive device. Unused devices must be stored in conductive material. Protect devices from static discharge and static fields. Stresses above 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 above 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. PIN CONFIGURATIONS 16-Pin Plastic DIP (Narrow) 16-Pin CerDIP CURRENT LIMIT/ SOFT START VREF – CURRENT SENSE + CURRENT SENSE + ERROR AMP – ERROR AMP COMP CT 1 2 3 4 5 6 7 8 TC18C46MJE TC28C46EPE TC38C46CPE 16 15 14 13 12 11 10 9 SHDN VIN OUTPUT B VDD GND OUTPUT A SYNC RT CURRENT LIMIT/ SOFT START VREF – CURRENT SENSE + CURRENT SENSE + ERROR AMP – ERROR AMP COMP CT 16-Pin SOIC (Wide) 1 2 3 4 5 6 7 8 TC28C46EOE TC38C46COE 16 15 14 13 12 11 10 9 SHDN VIN OUTPUT B VDD GND OUTPUT A SYNC RT 4-102 TELCOM SEMICONDUCTOR, INC. CMOS CURRENT MODE PWM CONTROLLERS TC18C46 TC28C46 TC38C46 ELECTRICAL CHARACTERISTICS: unless otherwise stated, these specifications apply for TA = – 55°C to +125°C for TC18C46; – 40°C to +85°C for the TC28C46; and 0°C to +70°C for the TC38C46; VIN = VDD = 16V; RT = 30.1k; CT = 270pF. TC18C46 TC28C46 Parameter Reference Section Output Voltage Line Regulation Load Regulation Temp Coefficient Total Output Range Long Term Drift Short Circuit Output Current Output Noise Voltage Tf = 25°C, IO = 1mA VIN = 8V to 16V IO = 1mA to 10mA Over Operating Range, (Note 1) Line, Load, and Temperature (Note 1) Tf = 125°C, 1000 Hrs (Note 1) VREF = 0V 10 Hz ≤ f ≤ 10 kHz, Tf = 25°C (Note 1) Tf = 25°C VIN = 8V to 16V Over Operating Range (Note 1) 5.0 — — — 4.97 — 20 — 96.5 — — 1.2 3.6 VDD –0.5 — — — — — — — 70 0.7 70 70 2 5 4.75 — 1.3 5.1 4 4 0.2 — 50 — 22 102 .1 .04 2 3.8 — — 8.5 8.5 ±5 ±5 ±10 ±10 90 1 90 90 4 10 4.9 0.4 2 5.2 20 20 0.5 5.24 — 70 — 106.5 2.0 0.06 3 4 — 0.5 — 5 50 ±25 ±100 ±100 — — — — — — 5.1 0.9 — 5.0 — — — 4.94 — 20 — 96.5 — — 1.2 3.6 VDD –0.5 — — — — — — — 70 0.7 70 70 2 5 4.75 — 1.3 5.1 4 4 0.2 — 50 — 22 101 .1 .04 2 3.8 — — 8.5 8.5 ±5 ±5 ±0.1 ±0.1 90 1 90 90 4 10 4.9 0.4 2 5.2 20 20 0.5 5.26 — 70 — 106.5 1.5 0.06 3 4 — 0.5 — 5 50 ±25 ±0.5 ±0.5 — — — — — — 5.1 0.9 — V mV mV mV/°C V mV mA µV(rms) kHz %/V %/°C mA V V V V V nA mV nA nA dB MHz dB dB mA mA V V V/µsec 1 2 3 4 5 6 7 TC38C46 Max Min Typ Max Units Test Conditions Min Typ Oscillator Section Initial Accuracy Voltage Coefficient Temp Coefficient Clock Ramp Reset Current Osc Ramp Amplitude Sync Output High Level Sync Output Low Level Sync Input High Level Sync Input Low Level Sync Input Current (Note 1) (Note 1) Pin 8 = 0V, (Note 1) Pin 8 = 0V, (Note 1) Sync Voltage = 5.25V, Pin 8 = 0V Error Amp Section Input Offset Voltage Input Bias Current Input Offset Current Open Loop Voltage Gain Gain Bandwidth Product CMRR PSRR Output Sink Current Output Source Current High Level Output Volt Low Level Output Volt Slew Rate ∆VO = 1V to 6V, RL = 100k Tf = 25°C (Note 1) VCM = 0V to 11V VIN = 8V to 16V V(EA –) = 5V, V(EA+) = 4.9V, V(CMPTR) = 1.2V V(EA –) = 5V, V(EA+) = 5.1V, V(CMPTR) = 2.5V RL = (CMPTR) 5kΩ to GND, ACL = 300 RL = (CMPTR) 5kΩ to GND, ACL = 300 8 TELCOM SEMICONDUCTOR, INC. 4-103 CMOS CURRENT MODE PWM CONTROLLERS TC18C46 TC28C46 TC38C46 ELECTRICAL CHARACTERISTICS (Cont): Unless otherwise stated, these specifications apply for TA = –55°C to +125°C for TC18C46; – 40°C to +85°C for the TC28C46; and 0°C to +70°C for the TC38C46; VIN = VDD = 16V; RT = 30.1k; CT = 270pF. TC18C46 TC28C46 Parameter Current Sense Section Amplifier Gain Max Differential Input Signal (VPin 4-VPin 3) Input Offset Voltage CMRR PSRR Input Bias Current Input Offset Current Input Common Mode Range Delay to Outputs (Notes 2, 3) (Note 2) (Note 2) VCM = 1V to 12V, (Note 2) VIN = 8V to 16V, (Note 2) (Note 1) (Note 1) (Note 1) Tf = 25°C, (Note 1) — (Shutdown Unlatched) 2.7 1.1 0.4 40 40 — — 0 150 ±1 3 320 0 140 — 100 125 3 1.5 0.65 60 60 ±1 ±0.1 — 225 ±25 3.5 360 — — — 50 250 3.6 1.8 0.85 — — ±100 ±2 11 400 — 4 400 VIN — 60 — 400 2.7 1.1 0.4 40 40 — — 0 150 ±1 3 320 0 140 — 100 125 3 1.5 0.65 60 60 ±1 ±0.1 — 225 ±25 3.5 360 — — — 50 250 3.4 1.8 0.85 — — ±100 ±2 11 400 mV 4 400 VIN — 65 — 400 V/V V V dB dB nA nA V nsec TC38C46 Max Min Typ Max Units Test Conditions Min Typ Current Limit Adjust Section Current Limit Voltage Offset Input Impedance kΩ mV V µA µA nsec nsec Ω Ω nsec nsec V V V mA µA Shutdown Terminal Section Threshold Voltage Input Voltage Range Min Latching Current (IPin 1) Max Non-Latching Current (IPin1) Min Pulse Width Delay to Outputs (Note 1) (Note 4) (Note 5) (Note 1) (Note 1) Output Section Output Low Level rDS (ON) Output High Level rDS (ON) Output Rise Time Output Fall Time ISINK = 20mA ISOURCE = 20mA CL = 1 µF CL = 1 µF — — — — 6.5 7.4 0.6 — — 10 20 55 55 7 7.8 0.8 1.2 250 20 35 90 90 7.3 8 1 2.5 350 — — — — 6.5 7.4 0.6 — — 10 20 55 55 7 7.8 0.8 1.2 250 20 35 90 90 7.3 8 1 2 350 Undervoltage Lockout Section Undervoltage Threshold Start Threshold Threshold Hysteresis Total Standby Current Supply Current Start-Up Current NOTES: 1. These parameters, although guaranteed over the recommended operating conditions, are not tested in production. 2. Parameter measured at trip point of latch with VPin 6 = VREF, VPin 16 = 0V. 3. Amplifier gain is defined as: 4-104 G = ∆VPin 7 ;∆VPin 4 = 0V to 1V ∆VPin 4 4. Current into Pin 1 guaranteed to latch circuit in shutdown state. 5. Current into Pin 1 guaranteed not to latch circuit in shutdown state. TELCOM SEMICONDUCTOR, INC. CMOS CURRENT MODE PWM CONTROLLERS TC18C46 TC28C46 TC38C46 Peak Current Limit Setup Resistors R1 and R2 at the CURRENT LIMIT input (pin 1) set the peak current limit (Figure 1). The potential at pin 1 is easily calculated: V1 = VREF R2 R1 + R2 The input pulse to pin 16 should be at least 100nsec wide and have an amplitude of at least 1V in order to get the minimum propagation delay from input to output. If these parameters are met, the delay should be less than 400nsec at 25°C; however, the delay time will increase as the device temperature rises. 1 2 3 4 5 6 7 Soft Restart From Shutdown A soft restart can be programmed if nonlatched shutdown operation is used. A capacitor at pin 1 will cause a gradual increase in potential toward V1. When the voltage at pin 1 reaches 0.75V, the PWM latch set input is removed and the circuit establishes a regulated output voltage. The soft-start operation forces the PWM output drivers to initially operate with minimum duty cycle and low peak currents. Even if a soft start is not required, it is necessary to insert a capacitor between pin 1 and ground if the current IL is greater than 140µA. This capacitor will prevent "noise triggering" of the latch, yet minimize the soft-start effect. R1 should be selected first. The shutdown circuit feature is not latched for (VREF – 0.35)/R1