LT1952EGN-1#PBF Linear Technology, LT1952EGN-1#PBF Datasheet

IC CTLR PWM SGL SWITCH 16-SSOP

LT1952EGN-1#PBF

Manufacturer Part Number
LT1952EGN-1#PBF
Description
IC CTLR PWM SGL SWITCH 16-SSOP
Manufacturer
Linear Technology
Datasheet

Specifications of LT1952EGN-1#PBF

Pwm Type
Current Mode
Number Of Outputs
1
Frequency - Max
560kHz
Duty Cycle
90%
Voltage - Supply
6.82 V ~ 25 V
Buck
No
Boost
No
Flyback
Yes
Inverting
No
Doubler
No
Divider
No
Cuk
No
Isolated
Yes
Operating Temperature
-40°C ~ 125°C
Package / Case
16-SSOP
Frequency-max
560kHz
Lead Free Status / RoHS Status
Lead free / RoHS Compliant

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LT1952EGN-1#PBFLT1952EGN-1
Manufacturer:
LT
Quantity:
10 000
Company:
Part Number:
LT1952EGN-1#PBFLT1952EGN-1
Manufacturer:
LINEAR/凌特
Quantity:
20 000
Company:
Part Number:
LT1952EGN-1#PBF
Manufacturer:
LT
Quantity:
3 375
Company:
Part Number:
LT1952EGN-1#PBF
Manufacturer:
LT/凌特
Quantity:
20 000
Company:
Part Number:
LT1952EGN-1#PBFLT1952EGN-1#TRPBF
Manufacturer:
LT/凌特
Quantity:
20 000
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APPLICATIONS
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TYPICAL APPLICATION
FEATURES
Synchronous Rectifi er Control for High Effi ciency
Programmable Volt-Second Clamp
Output Power Levels from 25W to 500W
Low Current Start-Up
(LT1952: 460μA; V
(LT1952-1: 400μA; V
True PWM Soft-Start
Low Stress Short-Circuit Protection
Precision 107mV Current Limit Threshold
Adjustable Delay for Synchronous Timing
Accurate Shutdown Threshold with Programmable
Hysteresis
Programmable Slope Compensation
Programmable Leading Edge Blanking
Programmable Frequency (100kHz to 500kHz)
Synchronizable to an External Clock up to 1.5 • f
Internal 1.23V Reference
2.5V External Reference
Current Mode Control
Small 16-Pin SSOP Package
Telecommunications Power Supplies
Industrial and Distributed Power
Isolated and Non Isolated DC/DC Converters
0.1μF
0.1μF
52.3k
100k
13k
36V to 72V Input, 12V at 20A Semi-Regulated Bus Converter
V
IN
340k
V
COMP
SS_MAXDC
SD_V
FB
SYNC
GND
PGND
REF
SUPPLY FROM BIAS
IN
WINDING OF T1
SEC
LT1952-1
IN
BLANK DELAY
On/Off = 14.25V/8.75V)
LT1952/
On/Off = 7.75V/6.5V)
40k
I
SENSE
SOUT
R
OUT
OSC
V
OC
40k
IN
178k
10μF
220pF
V
IN
Si7450
0.005Ω
T2
PA0905
T1
560Ω
OSC
Si7370
FG
SYNC
LTC3900
2
CG
DESCRIPTION
The LT
optimized to control the forward converter topology, using
one primary MOSFET. The LT1952/LT1952-1 provide
synchronous rectifi er control, resulting in extremely
high effi ciency. A programmable Volt-Second clamp
provides a safeguard for transformer reset that prevents
saturation. This allows a single MOSFET on the primary
side to reliably run at greater than 50% duty cycle for high
MOSFET, transformer and rectifi er utilization. The devices
include soft-start for controlled exit from shutdown and
undervoltage lockout. A precision 107mV current limit
threshold, independent of duty cycle, combines with soft-
start to provide hiccup short-circuit protection. The LT1952
is optimized for micropower bootstrap start-up from high
input voltages. The LT1952-1 allows start-up from lower
input voltages. Programmable slope compensation and
leading edge blanking allow optimization of loop bandwidth
with a wide range of inductors and MOSFETs. Each device
can be programmed over a 100kHz to 500kHz frequency
range and the part can be synchronized to an external
clock. The error amplifi er is a 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.
Single Switch Synchronous
All other trademarks are the property of their respective owners.
PA1494.242
PH4840
2
L1
®
1952/LT1952-1 are current mode PWM controllers
1952 TA01
47μF
16V
X5R
2
V
12V
20A
OUT
Forward Controller
LT1952/LT1952-1
16
14
12
10
8
36
12V Bus Converter
42
V
OUT
48
V
vs V
IN
54
(V)
IN
60
66
1952 TA01b
72
19521fd
1

Related parts for LT1952EGN-1#PBF

LT1952EGN-1#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

... 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 TAPE AND REEL LT1952EGN LT1952EGN#TR LT1952IGN LT1952IGN#TR ...

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

... Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT1952EGN/LT1952EGN-1 are guaranteed to meet performance specifi cations from 0°C to 125°C junction temperature. Specifi cations over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls ...

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 ...

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