LT/SG1525A, LT/SG3525A ly _LT/SG1527A, LT/SG3527A TECHNOLOGY _ Regulating Pulse Width , Modulators FEATURES DESCRIPTION Undervoltage Lockout with Hysteresis The LT1525A and LT1527A are improved general pur- Guaranteed 1% 5.1V Reference pose switching regulator control circuits. Included on the Guaranteed 10mV/1000 Hr Long Term Stability Chip are a trimmed 1% voltage subsurface zener refer- Latching PWM ence, oscillator, comparator and high current class B @ 8V to 35V Operation totem pole output drivers. Included in the design of the @ 100Hz to 400kHz Oscillator LT1525A are easy synchronization to an external clock, 400mA Source and Sink Current soft-start and adjustable deadtime control. A shutdown pin allows instantaneous shutdown. The LT1525A and LT1527A differ only in their output logic phasing. The LT1525A has a low output during the APPLICATIONS off state, while the LT1527A has a high output during Switching Power Supplies the off state. Both devices have undervoltage lockout = Motor Speed Control with about 0.5V hysteresis, giving reliable operation even m Power Converters with slowly varying supplies. The combination of improved features and advanced processing for high reliability make Linear Technology s switching regulators a supreme choice. . Ei ieee siete 16 | Bo | REFERENCE uw | | +VIN 1S REGULATOR LOCKOUT ; 4 JL! 10 OUTPUT A LT1525A Start-Up GROUND 12--menennendh INTERNAL 1 | 7 ae CIRCUITRY SYNC S OSC OUTPUT - 4 Ry 6f | Q | | : . OSCILLATOR ; F/F : | OUTPUT LOADED TO V~ Cy 5 Q t 14 | DISCHARGE 7 OUTPUT B | I _ | J output STAGE 5 - o oe eee eee wee oe > COMPENSATION F Ve 4 INV INPUT OUTPUT A NU INPUT SOFT-START 8 OUTPUT B 5k SHUTDOWN 10 14 ~ ~ ~ | = sGisa7A LT Wee 5-97LT/SG1525A, LT/SG3525A LT/SG1527A, LT/SG3527A ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) . ORDER PART Supply Voltage(+Vin) ...............008 +40V TOP VIEW NUMBER LogicInputs .................. 0.3V to +5.5V 1S, Analoginputs .................. 0.3V to +ViN rwviweur [1 is) Vee LT1525AJ Output Current, SourceorSink ............ 500mA ntinpur [2 is] + Vin LT1527AJ Reference OutputCurrent ..-.............. So0mA sync [3] 4] ourrur 8 LT3525AJ Oscillator Charging Current ................. 5mA osc ourur [a av LT3527AJ Power Dissipation at Ta = +25C (Note 2)... 1000mW LT3525AN Thermal Resistance: Junction toAmbient... 100C/W er fs] f] GROUND LT3527AN Power Dissipation at Tc = + 25C (Note 3)... 2000mW Ry [6 fi] ourrut a SG1525AJ oem Resistance sanction toCase ...... 60C/W oiscuance [7] Fa] SHUTDOWN SG1527AJ perating Temperature Range 15250, 1527A......... 0.00, 55C to 150C sorr-stant [3] E]conrensanon | OFS 3525A, 3527A.............00. 2... 0Cto70C onesie 18 Pry DLARTIC . G3525AN Storage Temperature Range ....... 65C to 150C $G3527AN Lead Temperature (Soldering, 10sec.) ..... +300C RECOMMENDED OPERATING CONDITIONS (Note 4) ~ oe re Input Voltage(+Vin).............. +8Vto +35V ReferenceLoad Current ....22....... OmA to 20mA Collector Supply Voltage (Vc) ...... +4.5Vto+35V = Oscillator Frequency Range........ 100Hz to 400kHz Sink/Source Load Current Oscillator Timing Resistor............ 2kQ to 150kQ (Steady State) ......00. 00.0008, OmAto100mA __ Oscillator Timing Capacitor ........ 0.001 pF to 0.1pF Sink/ Source Load Current (Peak)... . . OmAto400mA Deadtime Resistor Range.............. 00 to 5000 ELECTRICAL CHARACTERISTICS Vin = +20V unless otherwise noted aa LT1525A $G1525A PARAMETER CONDITIONS LT1527A ** $G1527A UNITS MIN TYP MAX MIN TYP MAX REFERENCE SECTION Output Voltage T= 25C 5.05 5.10 5.15 5.05 5.10 5.15 oy Line Regulation Vin = 8V to 35V e 5 10 10 20 mV Load Reguiation IL =OmA to 20mA e 20 50 20 50 mV Temperature Stability e 20 =650 C- --- 20 50 mV Total Output Variation Line, Load, and Temperature e 50 5.1 5.2 5.0 51 5.2 V Short Circuit Current Veer =0, Tj=25C 80 100 80 100 mA Output Noise Voltage 10HZ= f= 10kHz, Tj =25C 40 200 40 200 yuVrms Long Term Stability T)= 125C 1 10 20 50 mv/VKhr 5-98 7 @ AbeLT/SG1525A, LT/SG3525A LT/SG1527A, LT/SG3527A ELECTRICAL CHARACTERISTICS LT1525A SG1525A PARAMETER CONDITIONS LT1527A $G1527A UNITS MIN TYP MAX MIN TYP MAX OSCILLATOR SECTION (Note 6) initial Accuracy T, = 25C (Note 6) 2 6 2 6 % Voltage Stability Vin =8V to 35V e 05 1 03 1 % Temperature Stability e 3 6 3 6 % Minimum Frequency Ry = 150k, Cy =0. 1nF e 100 100 Hz Maximum Frequency Ry = 2k0, Cy = 1nF e 400 400 kHz Current Mirror lat = 2mA e 1.7 20 2.2 1.7 20 22 mA Clock Amplitude e 3.0 3.5 3.0 3.5 V Clock Width T= 25C 03 #05 1: 03 #05 1 BS Sync Threshold e 12 20 2.8 1.2 20 2.8 V Sync input Current Sync Voltage = 3.5V e 1.0 2.5 10 2.5 mA ERROR AMPLIFIER SECTION (Vcq =5.1V) . Input Offset Voltage e 05 45 05 5 mV Input Bias Current e 0.2 3 1 10 pA input Olfset Current e 0.5 1 pA DC Open Loop Gain Ry = 10MQ e 700 80 60 75 dB Gain Bandwidth Product Ay =00B, T;=25C (Note 5) 1 2 1 2 MHz Output Low Level e 0.2 0.5 0.2 0.5 V Output High Level e 3.8 5.6 ~ 3.8 5.6 V Common Mode Rejection Vow = 1.5V to 5.2V e 75 90 60 75 dB Supply Voltage Rejection Vin = 8V to 35V e 75 90 1 60 60 dB PWM COMPARATOR Minimum Duty Cycle e 0 0 % Maximum Duty Cycle 45 49 ~ 45 49 % Input Threshold Zero Duty Cycle (Note 6) e 0.6 0.9 . 0.6 0.9 V Input Threshold Max Duty Cycle (Note 6) e 3.3 3.6 3.3 3.6 WV Input Bias Current e 0.05 1.0 0.05 1.0 pA SOFT-START SECTION Soft-Start Current Vsputoown = OV e 25 50 80 25 50 80 pa Soft-Start Voltage VsyuToown = eV e 04 0.6 0.4 0.6 V Shutdown Input Current Vsputoown = 2.9V e 0.4 1.0 04 1.0 mA OUTPUT DRIVERS (Each Output) (V_ =20V) Undervoitage Lockout Hysteresis 0.2 06 1. 0.2 06 1 V Output Low Level Isinx = 20MA e 02 0.4 0.2 0.4 V Isink = 100MA e 1.0 2.0 10 2.0 v Output High Level Isournce = 20MA e 18 19 18 19 V Isqurce = 100mA e 17 18 17 18 Vv Undervoltage Lockout Vcomp and Vgg = High e 6 7 8 6 7 8 vo Collector Leakage Ve =35V (Note 7) e 200 200 pA Rise Time C, = InF, T;=25C (Note 5) 100 600 100 600 ns Fall Time C_ = 1nF, T)= 25C (Note 5) 50 300 50 300 ns Shutdown Delay Vsp =3V, Cs=0, T)= 25C (Note 5) 0.2 0.5 0.2 0.5 ps TOTAL STANDBY CURRENT Supply Current | Vin =35V | e | 14 20 14 20 mA LY Wie 5-99LT/SG1525A, LT/SG3525A LT/SG1527A, LT/SG3527A ELECTRICAL CHARACTERISTICS LT3525A $G3525A PARAMETER CONDITIONS LT3527A $G3527A UNITS MIN TYP MAX MIN TYP MAX REFERENCE SECTION Output Voltage T=25C 5.05 5.10 5.15 5.00 5.10 5.20 Vv Line Regulation Vin =8V to 35V e 5 10 ar) mV Load Regulation |, =OmA to 20mA e 20 ~=-50 20 = 50 mV Temperature Stability e 20 ~3= 50 20 350 mV Total Output Variation Line, Load, and Temperature e 4.95 5.1 5.25 4.95 5.25 V Short Circuit Current Vaer = 0, T)= 25C 80 100 80 100 mA Output Noise Voltage 10Hz< f= 10kHz, 7)= 25C 40 100 40 200 uVrms Long Term Stability Tj= 125C 1 10 20 50 mV/khr OSCILLATOR SECTION (Note 6) initial Accuracy T;=25C (Note 6) 2 6 2 6 % Voltage Stability Vin =8V to 35V e 05 2 1 2 % Temperature Stability e 3 6 3 6 % Minimum Frequency Ry = 150kQ, C7 =0.14F e 100 100 Hz Maximum Frequency Rr = 2k, C7 = 1nF e 400 400 kHz Current Mirror lay = 2mA e 1.7 20 2.2 1.7 20 2.2 mA Clock Amplitude e 3.0 3.6 3.0 3.5 V Clock Width Tj=25C 0.3 #05 41.0 03 #05 1.0 ps Sync Threshold e 1.2 20 28 1.2 20 28 V Sync Input Current Sync Voltage = 3.5V e 10 2.5 1.0 2.5 mA ERROR AMPLIFIER SECTION (Voy =5.1V) input Offset Voltage e 2 5 2 10 mV Input Bias Current e 1 3 1 10 pA input Offset Current e 0.5 1 pA DC Open Loop Gain R._= 10MQ e 70 80 60 75 dB Gain Bandwidth Product Ay =0dB, T;= 25C (Note 5) 1 2 1 2 MHz Output Low Level e 0.2 0.5 0.2 0.5 V Output High Level e 3.8 5.6 3.8 5.6 V Common Mode Rejection Vow = 1.5V to 5.2 e 75 =: 90 60 75 dB Supply Voltage Rejection Vin =8V to 35V e 75 90 50 60 dB PWM COMPARATOR Minimum Duty Cycle e 0 0 % Maximum Duty Cycle e 45 49 45 49 % Input Threshold Zero Duty Cycle (Note 6) e 0.6 0.9 06 09 V Input Threshold Max Duty Cycle (Note 6) e 3.3 3.6 3.3 3.6 V Input Bias Current e 0.05 1.0 0.05 1.0 pA SOFT-START SECTION Soft-Start Current Vsyutpown = OV e 25 50 #80 25 50 80 pA Soft-Start Voltage Vsyutoown = 2V e 0.4 0.6 0.4 0.6 V Shutdown Input Current VspuTDOWN = 2-5V e 0.4 1.0 04 1.0 mA 5-100 LJ WieLT/SG1525A, LT/SG3525A LT/SG1527A, LT/SG3527A ELECTRICAL CHARACTERISTICS LT3525A $63525A PARAMETER CONDITIONS LT3527A $G3527A UNITS MIN TYP MAX MIN TYP MAX OUTPUT DRIVERS (Each Output) (Vc =20V) Undervoitage Lockout Hysteresis 02 0.6 0.2 0.6 V Output Low Level Isinx = 20MA e 0.2 0.4 0.2 04 V Isink = 100mA e 1.0 2.0 1.0 2.0 Vv Output High Level Isource = 20MA e 18 383619 18 8619 V Isource = 100MA e 17 18 17 18 V Undervoltage Lockout , Vcomp and Vsg =High e 6 7 8 6 7 8 V Collector Leakage Vc=35V (Note 7) e 200 200 pA Rise Time C_ =1nF, T)=25C (Note 5) 100 600 100 600 ns Fall Time C, =1nF, Tj= 25C (Note 5) 50 = 300 50 =: 300 ns Shutdown Delay Vsp=3V, Cs =0, T) = 25C (Note 5) 0.2 0.5 0.2 0.5 ps TOTAL STANDBY CURRENT Supply Current | Viv=35V j@| 1420 | 142000 | mA The @ denotes the specifications which apply of the full operating Note 5: These parameters, although guaranteed over the recommended temperature range. operating conditions, are not 100% tested in production. Note 1: Values beyond which damage may occur. Note G: Tested at fogc =40kHz (R7=3.6k0, C7 =0.01pF, Ap =00). Note 2: Derate at 10mW/C for ambient temperatures above +50C. Note 7: Applies to 1525A/3525A only, due to polarity of output pulses. Note 3: Derate at 16mW/ C for case temperatures above + 25C. Note 4: Range over which the device is functional and parameter limits Ea are guaranteed. ; ; Error Amplifier Open Loop Oscillator Charge Time vs Ry Oscillator Discharge Time Frequency Response 1000 500 TT 4 100 500 Cr=1.0nF | | | Cr =2.0nF 80 =~ 400 q 200 e Cr =5.0nF-f fod / a N\ Cp=0 = 100 Ss ret | Ss N % 50 @ 300 | / / 3 Cp=1.0nF \ = 20 2 -00 | Tf Gr = 0.02nF 5 | Ry =20k z 5 $ 1 = - = 10 Cr=0. a ! / Cy =0.05pF g 2%0; Q = 5.0 =0.054F & | f / _ * " \ Cr 04 Fr "0 Wy Vf | oF & Ry=0 \. 2.0 = / /, Y/ Cy =0.1pF . 1.0 0 A Al 1) ~20 | | | 1.02.0 5.0 10 20 50 100200 500 1k 2k 5k 10k 0.10.2 0.51.02.0 5.0 10 20 50100200 500 1k 1.0 10 100 1.0k 10k 100k 1.0M 10M CHARGE TIME (xs) DISCHARGE TIME (us) f, FREQUENCY (Hz) LY Wine 5-101LT/SG1525A, LT/SG3525A LT/SG1527A, LT/SG3527A TYPICAL PERFORMANCE CHARACTERISTICS 1525A Output Saturation Characteristics LT1527A Start-Up 4 Vin=20V Ta=25C SATURATION VOLTAGE (V) Vout (V) SINK SATURATION, OUTPUT 0 0.01 0.02 005 0.10 02 O58 1 4 6 OUTPUT CURRENT, SOURCE OR SINK (A) Vin (V) 1525A/1527A 15258/1527A CL=1kpF, CL =1kpF, =5kpF, =5kpF, = 10kpF = 10kpF V =2.5V/DIV V =2.5V/DIV H =100ns/DIV H =100ns/DIV OUTPUT CURRENT OUTPUT CURRENT 100mA/DIV 100mA/DIV 100ns/ DIV 100ns/DIV APPLICATIONS INFORMATION Shutdown Options 1. An external open collector comparator or transistor /7/ 2. Shutdown can also be accomplished by pulling down can be used to pull down the compensation pin (9). on the soft-start pin (8). When using this approach, This will set the PWM latch and turn off both outputs. shutdown will not affect the amplifier compensation Pulse-by-pulse protection can be accomplished if the network; however, if a soft-start capacitor is used, it shutdown signal is momentary, since the PWM latch must be discharged, possibly slowing shutdown will be reset with each clock pulse. response. 5-102 LY WeLT/SG1525A, LT/SG3525A LT/SG1527A, LT/SG3527A APPLICATIONS INFORMATION 3. Applying a positive-going signal to the shutdown pin (10) will provide the most rapid shutdown of the out- puts if a soft-start capacitor is not used at pin 8. An external soft-start capacitor at pin 8 will slow shut- down response due to the discharge time of the soft- start capacitor. Discharge current is approximately twice the charging current. 4. The shutdown terminal can be used to set the PWM latch on a pulse-by-pulse basis if there is no external capacitance on pin 8. Soft-start characteristics may still be achieved by applying an external capacitor, blocking diode and charging resistor to the compen- sation pin (9). TYPICAL APPLICATIONS Single Ended Supply at rm p= OUTPUT Ri | A > >R2 - AA, Vv FOR SINGLE ENDED SUPPLIES, THE DRIVER OUTPUTS ARE GROUNDED. THE +V TERMINAL IS SWITCHED TO GROUND BY THE TOTEM- POLE SOURCE TRANSISTORS ON EVERY OSCILLATOR CYCLE. Power FETs Push-Pull Supply cal THE LOW SOURCE IMPEDANCE OF THE OUTPUT DRIVERS PROVIDES RAPID CHARGING OF POWER FET INPUT CAPACITANCE, WHILE MINIMIZING EXTERNAL COMPONENTS. LT Wee Bipolar Push-Pull Supply yt IN CONVENTIONAL PUSH-PULL BIPOLAR DESIGNS, FORWARD BASE DRIVE IS CONTROLLED BY R1-R3. RAPID TURN-OFF TIMES FOR THE POWER DEVICES ARE ACHIEVED WITH SPEED-UP CAPACITORS C1 AND C2. Driving Transformers Directly yt AA LOW POWER TRANSFORMERS CAN BE DRIVEN DIRECTLY BY THE 1525A. AUTOMATIC RESET OCCURS DURING DEADTIME, WHEN BOTH ENDS OF THE PRIMARY WINDING ARE SWITCHED TO GROUND. 9-103LT/SG1525A, LT/SG3525A LT/SG1S27A, LT/SG3527A TEST CIRCUIT REFERENCE REGULATOR PWM ADJ OSCILLATOR SOFT-START 5.0uF ao 2.0k V/1 METER t SHUTDOWN PACKAGE DESCRIPTION 16 Pin Cavity DIP (J) 16 Pin Molded DIP (N) a] wax oon eam) ash Po) sn T f IF t name-o01 eas-cor 1, ol [ams ~ollL 1 souasen, (0.203 - 0.305) (3.175) 8.100, ao} Le 2, 0.385 + 0.025 (2.540) (1.016) {9.7792 0.635) Tjmax Cia Sic Tjmax iA Sic LT/SG1525AJ 190C | 100C/W | 60C/W LT/SG3525AN | 105C | 100C/W | 60C/W LT/SG1527AS LT/SG3527AN LT/SG3525AJ 160C | 100C/W | 60C/W LT/SG3527AJ 5-104 were