current mode, pulse width modulators. They are improved
plug compatible versions of the industry standard UC1842
series. These devices have both improved speed and
lower quiescent current. The LT1241 series is optimized
for off-line and DC/DC converter applications. They con-
tain a temperature-compensated reference, high gain
error amplifier, current sensing comparator and a high
current totem pole output stage ideally suited to driv-
ing power MOSFETs. Start-up current has been reduced
to less than 250µA. Cross-conduction current spikes in
the output stage have been eliminated, making 500kHz
operation practical. Several new features have been incor-
porated. Leading edge blanking has been added to the
current sense comparator. Trims have been added to the
oscillator circuit for both frequency and sink current, and
both of these parameters are tightly specified. The out-
put stage is clamped to a maximum V
OUT
of 18V in the
on state. The output and the reference output are actively
pulled low during undervoltage lockout.
n
n
Low Start-Up Current: < 250µA
50ns Current Sense Delay
Current Mode Operation: To 500kHz
Pin Compatible with UC1842 Series
Undervoltage Lockout with Hysteresis
No Cross-Conduction Current
Trimmed Bandgap Reference
1A Totem Pole Output
Trimmed Oscillator Frequency and Sink Current
Active Pull-Down on Reference and Output During
Undervoltage Lockout
High Level Output Clamp: 18V
Current Sense Leading Edge Blanking
APPLICATIONS
n
n
Off-Line Converters
DC/DC Converters
All registered trademarks and trademarks are the property of their respective owners.
BLOCK DIAGRAM
REFERENCE ENABLE
5V REF
MAIN BIAS
REFERENCE PULL-DOWN
OUTPUT
PULL-DOWN
T
1V
S
R
6
OUTPUT
UV
LOCKOUT
8
7
V
REF
V
CC
R
T
/C
T
COMP
FB
4
5.6V
1mA
2
2.5V
OSCILLATOR
1
–
+
2R
R
–
+
BLANKING
5
18V
GND
+
1.5V
I
SENSE
3
–
1241 BD01
Rev B
Document Feedback
For more information
www.analog.com
1
LT1241 Series
ABSOLUTE MAXIMUM RATINGS
Supply Voltage ..........................................................25V
Output Current ........................................................± 1A*
Output Energy (Capacitive Load per Cycle) ............... 5µJ
Analog Inputs (Pins 2, 3) ............................... –0.3 to 6V
Error Amplifier Output Sink Current .......................10mA
Power Dissipation at T
A
≤
25°C..................................1W
Operating Junction Temperature Range
LT124XC................................................. 0°C to 100°C
LT124XI ............................................ – 40°C to 100°C
LT124XM
(Obsolete)
.......................... – 55°C to 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
*The 1A rating for output current is based on transient switching
requirements.
PIN CONFIGURATION
TOP VIEW
COMP
FB
I
SENSE
R
T
/C
T
1
2
3
4
8
7
6
5
V
REF
V
CC
OUTPUT
GND
TOP VIEW
COMP
FB
I
SENSE
R
T
/C
T
1
2
3
4
8
7
6
5
V
REF
V
CC
OUTPUT
GND
J8 PACKAGE 8-LEAD CERDIP
T
JMAX
= 125°C,
θ
JA
= 100°C/W
OBSOLETE PACKAGE
TOP VIEW
COMP 1
FB 2
I
SENSE
3
R
T
/C
T
4
8
7
6
5
V
REF
V
CC
OUTPUT
GND
N8 PACKAGE 8-LEAD PDIP
T
JMAX
= 100°C,
θ
JA
= 130°C/W
S8 PACKAGE 8-LEAD PLASTIC SO
T
JMAX
= 100°C,
θ
JA
= 150°C/W
ORDER INFORMATION
LEAD FREE FINISH
LT124XCJ8#PBF
LT124XCN8#PBF
LT124XCS8#PBF
LT124XIN8#PBF
LT124XIS8#PBF
LT124XMJ8#PBF
TAPE AND REEL
LT124XCJ8#TRPBF
LT124XCN8#TRPBF
LT124XCS8#TRPBF
LT124XIN8#TRPBF
LT124XIS8#TRPBF
LT124XMJ8#TRPBF
http://www.linear.com/product/LT1241#orderinfo
PART MARKING*
124X
124X
124X
124XI
124XI
PACKAGE DESCRIPTION
8-Lead CERDIP
8-Lead PDIP
8-Lead Plastic SO
8-Lead PDIP
8-Lead Plastic SO
OBSOLETE PACKAGE
8-Lead CERDIP
–55°C to 125°C
TEMPERATURE RANGE
0°C to 100°C
0°C to 100°C
0°C to 100°C
–40°C to 125°C
–40°C to 125°C
OBSOLETE PACKAGE
Consult ADI Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
Rev B
2
For more information
www.analog.com
LT1241 Series
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 2 and 3)
PARAMETER
Reference Section
Output Voltage
Line Regulation
Load Regulation
Temperature Stability
Total Output Variation
Output Noise Voltage
Long Term Stability
Output Short-Circuit Current
Oscillator Section
Initial Accuracy
Voltage Stability
Temperature Stability
Amplitude
Clock Ramp Reset Current
Error Amplifier Section
Feedback Pin Input Voltage
Input Bias Current
Open-Loop Voltage Gain
Unity-Gain Bandwidth
Power Supply Rejection Ratio
Output Sink Current
Output Source Current
Error Amplifier Section
Output Voltage High Level
Output Voltage Low Level
Current Sense Section
Gain
Maximum Current Sense Input Threshold
Power Supply Rejection Ratio
Input Bias Current
Delay to Output
Blanking Time
Blanking Override Voltage
V
PIN3
< 1.1V
l
l
l
l
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
4.925
l
l
TYP
5.000
3
–6
0.1
MAX
5.075
20
–25
5.13
UNITS
V
mV
mV
mV/°C
V
µV
mV
mA
kHz
kHz
%
%/°C
V
I
O
= 1mA, T
J
= 25°C
12V < V
CC
< 25V
1mA < I
VREF
< 20mA
Line, Load, Temp
10Hz < F < 10kHz, T
J
= 25°C
T
A
= 125°C, 1000 Hrs
l
l
4.87
50
5
–30
47.5
228
–90
50
248
– 0.05
1.7
7.9
8.2
2.50
90
1.3
6
–0.75
5.6
0.2
2.85
0.90
3.00
1.00
70
–1
50
100
1.5
25
–180
52.5
268
1
R
T
= 10k, C
T
= 3.3nF, T
J
= 25°C
R
T
= 13.0k, C
T
= 500pF, T
J
= 25°C
12V < V
CC
< 25V, T
J
= 25°C
T
MIN
< T
J
< T
MAX
T
J
= 25°C (Pin 4)
V
OSC
(Pin 4) = 2V, T
J
= 25°C
V
PIN1
= 2.5V
V
FB
= 2.5V
2 < V
O
< 4V
T
J
= 25°C
12V < V
CC
< 25V
V
PIN2
= 2.7V, V
PIN1
= 1.1V
V
PIN2
= 2.3V, V
PIN1
= 5V
V
PIN2
= 2.3V, R
L
= 15k to GND
V
PIN2
= 2.7V, R
L
= 15k to Pin 8
l
l
l
l
l
l
8.5
2.58
–2
mA
V
µA
dB
MHz
dB
mA
mA
V
2.42
65
0.7
60
2
–0.5
5
2
l
l
1.1
3.15
1.10
10
100
V
V/V
V
dB
µA
ns
ns
V
Rev B
For more information
www.analog.com
3
LT1241 Series
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 2 and 3)
PARAMETER
Output Section
Output Low Level
Output High Level
Rise Time
Fall Time
Output Clamp Voltage
Undervoltage Lockout
Start-Up Threshold
LT1241
LT1242/LT1244
LT1243/LT1245
Minimum Operating Voltage
LT1241/LT1243/LT1245
LT1242/LT1244
Hysteresis
LT1241
LT1242/LT1244
LT1243/LT1245
PWM
Maximum Duty Cycle
LT1241/LT1244/LT1245
LT1242/LT1243
Minimum Duty Cycle
Total Device
Start-Up Current
Operating Current
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
l
l
l
l
l
l
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
I
OUT
= 20mA
I
OUT
= 200mA
I
OUT
= 20mA
I
OUT
= 200mA
MIN
l
l
l
l
TYP
0.25
0.75
MAX
0.4
2.2
UNITS
V
V
V
V
12.0
11.75
50
30
80
60
19.5
C
L
= 1nF, T
J
= 25°C
C
L
= 1.0nF, T
J
= 25°C
I
O
= 1mA
l
ns
ns
V
18
9.0
15
7.8
7.0
9.0
1.6
5.5
0.4
9.6
16
8.4
7.6
10
2.0
6.0
0.8
10.2
17
9.0
8.2
11
V
V
V
V
V
V
V
V
T
J
= 25°C
T
J
= 25°C
l
46
94
48
96
0
170
7
250
10
%
%
%
µA
mA
Note 2:
Unless otherwise specified, V
CC
= 15V, R
T
= 10k, C
T
= 3.3nF.
Note 3:
Low duty cycle pulse techniques are used during test to maintain
Such as the title: Samsung 6410 nboot failed.. Even the debug prot did not respond! Measuring the flash signal showed action only for the first time.. Then the entire board became unresponsive.. >< No...
When the trolley (i.e., bridge body) of large and medium-sized bridge cranes such as 5t and 10t cranes moves, it is generally driven by two wound asynchronous motors, controlled by a cam controller, a...
[table][tr][td]I designed a UART controller. The simulation before and after Modelsim are correct. However, after loading it to the FPGA on the board, I send and receive data through the serial port d...
[i=s]This post was last edited by dcexpert on 2017-10-7 22:32[/i] [size=14px]With the dedicated research and support of netizen ImHori, PythonEditor Chinese version finally supports simulation running...
Today I am learning about the output of the MC33172 op amp. In the open loop state, the positive power supply is 15V and the negative power supply is -15V. The input pins are floating. VOUT1= 14.98 V ...
The TIA Portal software's shift instructions shift the contents of an accumulator bit by bit to the left or right. The number of bits shifted is determined by N. A left shift of N bits multiplies t...[Details]
Wave soldering is a crucial electronic component soldering technique used in the production of a wide range of electronic devices, from home appliances to computers to avionics. The process is wide...[Details]
Nios II is a configurable 16-/32-bit RISC processor. Combined with a rich set of peripheral-specific instructions and hardware acceleration units, it provides a highly flexible and powerful SOPC sy...[Details]
"Have you set your calendar reminder?"
On August 24, Nvidia Robotics' official account posted a photo of a black gift box on a social media platform, with an attached greeting card sig...[Details]
Long ago, the lifespan of cars in my country was 15 years. Once a car reached 15 years old, it was forced to be scrapped. However, the policy was later changed. As long as the car does not exceed 6...[Details]
As time goes by, people are increasingly concerned about their own and their families' health. However, existing monitoring devices for individual vital signs have struggled to gain market share du...[Details]
On August 25th, Apple's expansion in India encountered new troubles. According to Bloomberg, Foxconn Technology Group has recalled approximately 300 Chinese engineers from India, further hindering ...[Details]
introduction
The concept of the smart home is gradually developing and gaining market acceptance. We believe its ultimate form lies in the interconnection of all home appliances through open i...[Details]
As AI accelerates across industries, the demand for data center infrastructure is also growing rapidly.
Keysight Technologies, in collaboration with Heavy Reading, released the "Beyo...[Details]
With the increasing popularity of automated equipment, linear modules, a common auxiliary device for automated equipment, have also seen a bright future. In particular, in recent years, many small ...[Details]
Shenzhen Baowei Power Supply high frequency pure sine wave power, communication inverter power supply has two communication interfaces, RS232 and R485 interfaces, their functions and characteristic...[Details]
Methods of DC motor speed regulation:
1. The voltage regulator can be used to change the input voltage and speed directly, which is often used for large kilowatt-level motors.
2. Thyristo...[Details]
Batteries, at the core of new energy vehicles, are crucial to vehicle performance and range. Existing automotive batteries are categorized into lead-acid and lithium batteries. Currently, new energ...[Details]
Renesas Electronics' new ultra-low-power RA4C1 MCU features advanced security and a dedicated peripheral set, making it ideal for metering and other applications.
The new product mee...[Details]
introduction
As core electronic components used in vastly different fields, automotive-grade chips and mobile/consumer-grade chips exhibit significant differences in their...[Details]
Embedded System
京公网安备 11010802033920号
EEWORLD
