LT1952EGN#PBF Linear Technology, LT1952EGN#PBF Datasheet
LT1952EGN#PBF
Specifications of LT1952EGN#PBF
Available stocks
Related parts for LT1952EGN#PBF
LT1952EGN#PBF Summary of contents
Page 1
... The error amplifi true op amp, allowing a wide range of compensation networks. The LT1952/LT1952-1 are available in a small 16-pin SSOP package. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners ...
Page 2
... REF Operating Junction Temperature Range (Notes 2, 5) ............................................–40°C to 125°C Storage Temperature Range ...................–65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL LT1952EGN#PBF LT1952EGN#TRPBF LT1952IGN#PBF LT1952IGN#TRPBF LT1952EGN-1#PBF LT1952EGN-1#TRPBF LT1952IGN-1#PBF LT1952IGN-1#TRPBF LEAD BASED FINISH ...
Page 3
ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are 0.1μF , SD_V = 2V, BLANK = 121k, DELAY = 121k, I SEC PARAMETER V (LT1952 (LT1952) IN OFF V (LT1952) IN HYSTERESIS V (LT1952-1) IN ...
Page 4
LT1952/LT1952-1 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are 0.1μF , SD_V = 2V, BLANK = 121k, DELAY = 121k, I SEC PARAMETER SOUT DRIVER SOUT Clamp Voltage SOUT Low Level SOUT High Level SOUT Active Pull-Off ...
Page 5
TYPICAL PERFORMANCE CHARACTERISTICS FB Voltage vs Temperature 1.25 1.24 1.23 1.22 1.21 1.20 –50 – 100 TEMPERATURE (°C) 1952 G01 V Start-up Current IN vs Temperature 600 SD_V = 1.4V SEC 550 500 LT1952 450 400 ...
Page 6
LT1952/LT1952-1 TYPICAL PERFORMANCE CHARACTERISTICS COMP Source Current vs Temperature 12 COMP = 1.6V 10.0 7.5 CURRENT OUT OF PIN 5.0 –50 – 100 TEMPERATURE (°C) 1952 G10 I Maximum Threshold SENSE vs COMP ...
Page 7
TYPICAL PERFORMANCE CHARACTERISTICS BLANK Duration vs R BLANK 1000 T = 25°C A 800 600 400 200 100 120 140 R (k) BLANK 1952 G26 OUT Rise/Fall Time vs OUT Load Capacitance 125 T ...
Page 8
LT1952/LT1952-1 PIN FUNCTIONS COMP (Pin 1): Output Pin of the Error Amplifi er. The error amplifi amp, allowing various compensation networks to be connected between the COMP pin and FB pin for optimum transient response. The ...
Page 9
TIMING DIAGRAM SOUT OUT SS_MAXDC FAULTS TRIGGERING SOFT-START V < 8.75V IN OR SD_V < 1.32V (UVLO) SEC OR OC > 107mV (OVERCURRENT) BLOCK DIAGRAM START-UP LT1952 V ON INPUT CURRENT (ISTART OFF I = ...
Page 10
LT1952/LT1952-1 OPERATION Introduction The LT1952/LT1952-1 are current mode synchronous PWM controllers optimized for control of the simplest forward converter topology—using only one primary MOSFET. The LT1952/LT1952-1 are ideal for 25W to 500W power systems where very high effi ciency and ...
Page 11
OPERATION catastrophic damage. Many converters solve this problem by limiting the operational duty cycle of the MOSFET to 50% or less—or by using a fi xed (non-adaptive) maximum duty cycle clamp with very large voltage rated MOSFETs. The LT1952/LT1952-1 provide ...
Page 12
LT1952/LT1952-1 OPERATION Slope Compensation The current mode architecture requires slope compensa- tion to be added to the current sensing loop to prevent subharmonic oscillations which can occur for duty cycles above 50%. Unlike most current mode converters which have a ...
Page 13
APPLICATIONS INFORMATION current (460μA LT1952; 400μA LT1952-1) allows a large resistor to be connected between system input supply and V . Once the part is turned on, input current increases to IN drive the IC (4.5mA) and the output drivers ...
Page 14
LT1952/LT1952-1 APPLICATIONS INFORMATION Blanking is provided in 2 phases (Figure 6): The fi rst phase automatically blanks during gate rise time. Gate rise times can vary depending on MOSFET type. For this reason the LT1952/LT1952-1 perform true ‘leading edge blanking’ ...
Page 15
APPLICATIONS INFORMATION Programming Synchronous Rectifi er Timing: SOUT to OUT delay (‘t ’) DELAY The LT1952/LT1952-1 have an additional output SOUT which provides a ±50mA peak drive clamped to 12V. In applications requiring synchronous rectifi cation for high effi ciency, ...
Page 16
LT1952/LT1952-1 APPLICATIONS INFORMATION Example calculation for (2) For R = 35.7k 100k REF R = 40k 200kHz and SD_V DELAY OSC this gives SS_MAXDC(DC) = 1.84V, t and Maximum Duty ...
Page 17
APPLICATIONS INFORMATION (A) V > 14.25* (7.75V LT1952-1), and IN (B) SD_V > 1.32V, and SEC (C) OC < 107mV, and (D) SS_MAXDC < 0.45V (SS_MAXDC reset threshold) *V > 8.75V (6.5V LT1952- for latch reset if the ...
Page 18
LT1952/LT1952-1 APPLICATIONS INFORMATION V (t) = SS_MAXDC(DC) (1 – give • (–1) • ln(1 – V /SS_MAXDC(DC)) SS where SS_MAXDC voltage at time t SS SS_MAXDC(DC) = programmed DC voltage setting maximum ...
Page 19
APPLICATIONS INFORMATION For SD_V = 1.32V, fOSC = 200kHz and R SEC This gives and t = 40ns. DELAY Re-arranging the above equation to solve for SS_MAXDC = V SS(REG • f )(SD_V ...
Page 20
LT1952/LT1952-1 APPLICATIONS INFORMATION LOAD CURRENT (A) Figure 12. LT1952-Based Synchronous Forward Converter Effi ciency vs Load Current (For Circuit in Figure 14) 16 SOUT SOUT SD_V SEC 5 SS_MAXDC ...
Page 21
APPLICATIONS INFORMATION 48V to Isolated 12V, 20A (No Opto-Coupler) ‘Bus Converter’ The wide programmable range and accuracy of the LT1952/LT1952-1 Volt-Second clamp makes the LT1952/ LT1952-1 an ideal choice for ‘Bus Converter’ applications where the Volt-Second clamp provides line regulation ...
Page 22
LT1952/LT1952-1 APPLICATIONS INFORMATION 36V to 72V Input, 3.3V 40A Converter An LT1952-based synchronous forward converter provides the ideal solution for power supplies requiring high effi ciency at low output voltages and high load currents. The 3.3V 40A solution in Figure ...
Page 23
... Cycle Clamp for Bus Converter Applications (Adding Rx) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
Page 24
... REF .150 – .157** (3.810 – 3.988 .004 – .0098 (0.102 – 0.249) .0250 GN16 (SSOP) 0204 (0.635) BSC ≤ 11V, N-channel IN LT 1108 REV D • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2004 19521fd ...