LX1555MY Microsemi Analog Mixed Signal Group, LX1555MY Datasheet
LX1555MY
Manufacturer Part Number
LX1555MY
Description
IC PWM CURRENT MODE 8.4V 8DIP
Manufacturer
Microsemi Analog Mixed Signal Group
Datasheet
1.LX1554CM.pdf
(18 pages)
Specifications of LX1555MY
Pwm Type
Current Mode
Number Of Outputs
1
Frequency - Max
500kHz
Duty Cycle
48%
Voltage - Supply
11 V ~ 25 V
Buck
Yes
Boost
Yes
Flyback
Yes
Inverting
No
Doubler
No
Divider
No
Cuk
No
Isolated
Yes
Operating Temperature
-55°C ~ 125°C
Package / Case
8-DIP
Frequency-max
500kHz
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
T
Copyright © 1994
Rev. 1.0b,2005-03-01
-55 to 125
-40 to 85
H E
T
Note: Available in Tape & Reel. Append the letters “TR” to the part number (i.e. LX1552CDM-TR).
INPUT
0 to 70
(250µA max), current mode control ICs offer new
levels of energy efficiency for offline converter
applications.
personal computer and CRT power supplies
although they can be used in any number of off-line
applications where energy efficiency is critical.
Coupled with the fact that the LX155x series
requires a minimal set of external components, the
series offers an excellent value for cost conscious
consumer applications.
demonstrates a significant power reduction as
compared with other similar off-line controllers.
Table 1 compares the SG384x, UC384xA and the
LX155x start-up resistor power dissipation. The
LX155x offers an overall 4X reduction in power
dissipation.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
AC
A
(°C)
The LX155x family of ultra-low start-up current
Optimizing energy efficiency, the LX155x series
I
N F I N I T E
Typical Application of LX155x Using Its MicroPower Start-Up Feature
M
RoHS Compliant / Pb-free
Transition DC: 0503
LX155xCM
LX155xIM
They are ideally optimized for
Plastic DIP
8-Pin
-
P
O W E R
11861 W
LX1552
LX1554
V
or
P R O D U C T H I G H L I G H T
CC
R
I
ST
ST
O F
DM
ESTERN
D E S C R I P T I O N
RoHS Compliant / Pb-free
L
Transition DC: 0440
I
I N
LX155xCDM
LX155xIDM
N N O V A T I O N
A
Plastic SOIC
F
8-Pin
VENUE
I N I T Y
-
Note: Calculation is done for universal AC input
specification of V
the following equation: (resistor current is selected to be 2
* I
Design Using
Max. Start-up Current
Specification (I
Typical Start-up Resistor
Value (R
Max. Start-up Resistor
Power Dissipation (P
, G
ST
PACKAGE ORDER INFO
Additionally, the precise oscillator discharge
current
considerable flexibility in optimizing system duty
cycle consistency.
improved load regulation, pulse by pulse current
limiting and inherent protection of the power
supply output switch. The LX155x includes a
bandgap reference trimmed to 1%, an error
amplifier, a current sense comparator internally
clamped to 1V, a high current totem pole output
stage for fast switching of power MOSFETs, and
an externally programmable oscillator to set
operating frequency and maximum duty cycle.
The under voltage lock-out circuitry is designed to
operate with as little as 250µA of supply current
permitting very efficient bootstrap designs.
ARDEN
@ V
The current mode architecture demonstrates
M
ACMIN
ST
R
)
I C R O E L E C T R O N I C S
G
)
ST
ROVE
gives
ST
=
ACMIN
)
D
RoHS Compliant / Pb-free
, CA. 92841, 714-898-8121, F
V
U
2 • I
R
ACMIN
= 90V
Transition DC: 0440
)
L T R A
the
LX155xCD
ST
LX155xID
Plastic SOIC
14-Pin
SG384x UC384xA
RMS
1000µA
, P =
2.26W
62KΩ
power
- L
R
-
to V
O W
P
ACMAX
2V
R O D U C T I O N
R
AC MAX
supply
S
124KΩ
500µA
1.13W
ST
2
= 256V
T A R T
I
RMS
- U
designer
N C
AX
LX155x
Y
248KΩ
250µA
0.56W
using
: 714-893-2570
P
.
LX155xMY
C
U R R E N T
Ceramic DIP
8-Pin
LX1552
LX1553
LX1554
LX1555
-
-
Part #
D
Available Options Per part#
A T A
, C
Ultra-Low Start-up Current (150µA
Typical)
Trimmed Oscillator Discharge
Current (±2% Typical)
Initial Oscillator Frequency Better
Than ±4%
Output Pulldown During UVLO
Precision 2.5V Reference (±2
maximum)
Current Sense Delay to Output
(150ns Typical)
Automatic Feed Forward
Compensation
Pulse-by-Pulse Current Limiting
Enhanced Load response
Characteristics
Under-Voltage Lockout with
Hysteresis
Double Pulse Suppression
High Current Totem Pole Output
(±1A Peak)
500KHz Operation
Economy Off-Line Flyback or
Forward Converters
DC-DC Buck or Boost Converters
Low Cost DC Motor Control
Start-Up
Voltage
K E Y F E A T U R E S
A P P L I C A T I O N S
8.4V
8.4V
U R R E N T
16V
16V
LX1552/3/4/5
S
PW
RoHS Compliant / Pb-free
H E E T
Transition DC: 0442
Hysteresis
LX155xCPW
- M
0.8V
0.8V
6V
6V
Plastic TSSOP
20-Pin
O D E
-
-
Max. Duty
P W M
<100%
<100%
Cycle
<50%
<50%
1
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LX1555MY Summary of contents
Page 1
The LX155x family of ultra-low start-up current (250µA max), current mode ...
Page 2
LX1552/3/4 ...
Page 3
(Unless otherwise specified, these specifications apply over the operating ambient temperatures for LX155xC with 0°C ...
Page 4
LX1552/3/4/5 Parameter Under-Voltage Lockout Section Start Threshold Min. Operation Voltage After Turn-On PWM Section Maximum Duty ...
Page 5
GRAPH / CURVE INDEX Characteristic Curves FIGURE # 1. OSCILLATOR FREQUENCY vs. TIMING RESISTOR 2. ...
Page 6
LX1552/3/4/5 FIGURE 1. — OSCILLATOR FREQUENCY vs. TIMING RESISTOR 1000 100 C = 6.8nF T 10 ...
Page 7
FIGURE 5. — OUTPUT INITIAL ACCURACY vs. TEMPERATURE 65.0 LX1552 and LX1553 only 63.5 62.0 ...
Page 8
LX1552/3/4/5 FIGURE 9. — E.A. INPUT VOLTAGE vs. TEMPERATURE 2.55 2.54 2.53 2.52 2.51 2.50 2.49 ...
Page 9
FIGURE 13. — DYNAMIC SUPPLY CURRENT vs. OSCILLATOR FREQUENCY 25° ...
Page 10
LX1552/3/4/5 FIGURE 17. — START-UP THRESHOLD vs. TEMPERATURE 17.0 16.8 16.6 16.4 16.2 16.0 15.8 15.6 ...
Page 11
FIGURE 21. — OUTPUT SATURATION VOLTAGE vs. OUTPUT CURRENT and TEMPERATURE 6 ...
Page 12
LX1552/3/4/5 IC DESCRIPTION The LX1552/3/4/5 series of current mode PWM controller IC's are designed to offer ...
Page 13
VOLTAGE REFERENCE The voltage reference is a low drift bandgap design which provides +5.0V to ...
Page 14
LX1552/3/4/5 OSCILLATOR (continued) The oscillator is designed such that many values of R give the same ...
Page 15
CURRENT SENSE COMPARATOR AND PWM LATCH Switch current is sensed by an external sense resistor ...
Page 16
LX1552/3/4/5 FIGURE 30. — CURRENT SENSE SPIKE SUPPRESSION LX155x ...
Page 17
...
Page 18
LX1552/3/4 ...