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LX1555CDM

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18
OBSOLETE PRODUCT
NOT RECOMMENDED FOR NEW DESIGNS
P
RODUCTION
D
ATA
S
HEET
T
HE
I
NFINITE
P
OWER OF
I
NNOVATION
L
IN
F
INITY
M
ICROELECTRONICS
I
NC
.
11861
W
ESTERN
A
VENUE
,
G
ARDEN
G
ROVE
,
CA.
92841,
714-898-8121,
F
AX
:
714-893-2570
1
Copyright © 1994
Rev. 1.0b,2005-03-01
LX1552/3/4/5
U
LTRA
-L
OW
S
TART
-U
P
C
URRENT
,
C
URRENT
-M
ODE
PWM
DESCRIPTION
The LX155x family of ultra-low start-up current
(250µA max), current mode control ICs offer new
levels of energy efficiency for offline converter
applications. They are ideally optimized for
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.
Optimizing energy efficiency, the LX155x series
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.
Additionally, the precise oscillator discharge
current gives the power supply designer
considerable flexibility in optimizing system duty
cycle consistency.
The current mode architecture demonstrates
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.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
PRODUCT HIGHLIGHT
Typical Application of LX155x Using Its MicroPower Start-Up Feature
I
ST
R
ST
V
CC
AC
I
NPUT
LX1552
or
LX1554
Design Using SG384x UC384xA LX155x
Max. Start-up Current
Specification (I
ST
)
1000µA 500µA
250µA
Typical Start-up Resistor
Value (R
ST
)
62KΩ 124KΩ
248KΩ
Max. Start-up Resistor
Power Dissipation (P
R
)
2.26W 1.13W
0.56W
Note: Calculation is done for universal AC input
specification of V
ACMIN
= 90V
RMS
to V
ACMAX
= 256V
RMS
using
the following equation: (resistor current is selected to be 2
* I
ST
@ V
ACMIN
)
2
A
CMIN AC MAX
ST R
ST
ST
2V
V
R= , P=
R
2•I
KEY FEATURES
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
APPLICATIONS
Economy Off-Line Flyback or
Forward Converters
DC-DC Buck or Boost Converters
Low Cost DC Motor Control
Available Options Per part#
Part #
Start-Up
Voltage
Hysteresis
Max. Duty
Cycle
LX1552 16V 6V <100%
LX1553 8.4V 0.8V <100%
LX1554 16V 6V <50%
LX1555 8.4V 0.8V <50%
PACKAGE ORDER INFO
M
Plastic DIP
8-Pin
DM
Plastic SOIC
8-Pin
D
Plastic SOIC
14-Pin
Y
Ceramic DIP
8-Pin
PW
Plastic TSSOP
20-Pin
T
A
(°C)
RoHS Compliant / Pb-free
Transition DC: 0503
RoHS Compliant / Pb-free
Transition DC: 0440
RoHS Compliant / Pb-free
Transition DC: 0440
RoHS Compliant / Pb-free
Transition DC: 0442
0 to 70
LX155xCM LX155xCDM LX155xCD
-
LX155xCPW
-40 to 85
LX155xIM LX155xIDM LX155xID
- -
-55 to 125
- - -
LX155xMY
-
Note: Available in Tape & Reel. Append the letters “TR” to the part number (i.e. LX1552CDM-TR).
OBSOLETE PRODUCT
NOT RECOMMENDED FOR NEW DESIGNS
U
LTRA
-L
OW
S
TART
-U
P
C
URRENT
, C
URRENT
-M
ODE
PWM
LX1552/3/4/5
PRODUCT DATABOOK 1996/1997
Copyright © 1994
Rev. 1.0b
2
P
RODUCTION DATA SHEET
ABSOLUTE MAXIMUM RATINGS (Note 1)
Supply Voltage (Low Impedance Source)..................................................................30V
Supply Voltage (I
CC
< 30mA).........................................................................Self Limiting
Output Current.............................................................................................................±1A
Output Energy (Capacitive Load)................................................................................5µJ
Analog Inputs (Pins 2, 3)...........................................................................-0.3V to +6.3V
Error Amp Output Sink Current...............................................................................10mA
Power Dissipation at T
A
= 25°C (DIL-8)......................................................................1W
Operating Junction Temperature
Ceramic (Y Package)............................................................................................150°C
Plastic (M, DM, D, PW Packages)........................................................................150°C
Storage Temperature Range....................................................................-65°C to +150°C
Lead Temperature (Soldering, 10 Seconds)............................................................300°C
PACKAGE PIN OUTS
V
REF
V
CC
OUTPUT
GND
COMP
V
FB
I
SENSE
R
T
/C
T
1 8
27
36
45
M & Y PACKAGE
(Top View)
DM PACKAGE
(Top View)
V
REF
V
CC
OUTPUT
GND
COMP
V
FB
I
SENSE
R
T
/C
T
1 8
27
36
45
V
REF
N.C.
V
CC
V
C
OUTPUT
GND
PWR GND
COMP
N.C.
V
FB
N.C.
I
SENSE
N.C.
R
T
/C
T
1 14
213
312
411
510
69
78
D PACKAGE
(Top View)
PW PACKAGE
(Top View)
1 20
219
318
417
516
615
714
813
912
10 11
N.C.
N.C.
COMP
V
FB
N.C.
I
SENSE
N.C.
R
T
/C
T
N.C.
N.C.
N.C.
N.C.
V
REF
N.C.
V
CC
V
C
OUTPUT
GND
PWR GND
N.C.
M PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θθ
θθ
θ
JA
95°C/W
DM PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θθ
θθ
θ
JA
165°C/W
D PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θθ
θθ
θ
JA
120°C/W
Y PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θθ
θθ
θ
JA
130°C/W
PW PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θθ
θθ
θ
JA
144°C/W
Junction Temperature Calculation: T
J
= T
A
+ (P
D
x θ
JA
).
The θ
JA
numbers are guidelines for the thermal performance of the device/pc-board system.
All of the above assume no ambient airflow
THERMAL DATA
Note 1.Exceeding these ratings could cause damage to the device. All voltages are with respect
to Ground. Currents are positive into, negative out of the specified terminal. Pin
numbers refer to DIL packages only.
Pb-free / RoHS Peak Package Solder Reflow Temp. (40 second max. exposure)................ 260°C (+0, -5)
RoHS / Pb-free 100% Matte Tin Lead Finish
RoHS / Pb-free 100% Matte Tin Lead Finish
RoHS / Pb-free 100% Matte Tin Lead Finish
M Package RoHS / Pb-free 100% Matte Tin Lead Finish
OBSOLETE PRODUCT
NOT RECOMMENDED FOR NEW DESIGNS
U
LTRA
-L
OW
S
TART
-U
P
C
URRENT
, C
URRENT
-M
ODE
PWM
LX1552/3/4/5
PRODUCT DATABOOK 1996/1997
3
Copyright © 1994
Rev. 1.0b
PRODUCTION DATA SHEET
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the operating ambient temperatures for LX155xC with 0°C ≤ T
A
≤ 70°C, LX155xI with -40°C ≤ T
A
≤ 85°C, LX155xM
with -55°C ≤ T
A
≤ 125°C; V
CC
=15V (Note 5); R
T
=10K; C
T
=3.3nF. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the
ambient temperature.)
Reference Section
Parameter
Symbol
Test Conditions
Output Voltage V
REF
T
A
= 25°C, I
L
= 1mA
Line Regulation 12 ≤ V
IN
≤ 25V
Load Regulation 1 ≤ I
O
≤ 20mA
Temperature Stability (Note 2 & 7)
Total Output Variation Over Line, Load, and Temperature
Output Noise Voltage (Note 2) V
N
10Hz ≤ f ≤ 10kHz, T
A
= 25°C
Long Term Stability (Note 2) T
A
= 125°C, t = 1000hrs
Output Short Circuit I
SC
LX155xC
Units
Min.Typ.Max.Min.Typ.Max.
LX155xI/155xM
4.955.005.054.955.005.05 V
620 620mV
625 625mV
0.2 0.4 0.2 0.4 mV/°C
4.9 5.1 4.9 5.1 V
50 50 µV
525 525mV
-30 -100-180 -30 -100-180 mA
Oscillator Section
Initial Accuracy (Note 6) T
A
= 25°C
T
A
= 25°C, R
T
= 698Ω, C
T
= 22nF, LX1552/3 only
Voltage Stability 12 ≤ V
CC
≤ 25V
Temperature Stability (Note 2) T
MIN
≤ T
A
≤ T
MAX
Amplitude (Note 2) V
PIN 4
peak to peak
Discharge Current I
D
T
A
= 25°C, V
PIN 4
= 2V
V
PIN 4
= 2V, T
MIN
≤ T
A
≤ T
MAX
48.550.552.548.550.552.5 kHz
56 58 60 56 58 60 kHz
0.2 1 0.2 1 %
55%
1.7 1.7 V
8.0 8.3 8.6 8.0 8.3 8.6 mA
7.6 8.8 7.8 8.8 mA
Output Voltage Low Level V
OL
I
SINK
= 20mA
I
SINK
= 200mA
Output Voltage High Level V
OH
I
SOURCE
= 20mA
I
SOURCE
= 200mA
Rise Time (Note 2) T
R
T
A
= 25°C, C
L
= 1nF
Fall Time (Note 2) T
F
T
A
= 25°C, C
L
= 1nF
UVLO Saturation V
SAT
V
CC
= 5V, I
SINK
= 10mA
Error Amp Section
Current Sense Section
Gain (Note 3 & 4) A
VOL
Maximum Input Signal (Note 3) V
PIN 1
= 5V
Power Supply Rejection Ratio (Note 3) PSRR 12 ≤ V
CC
≤ 25V
Input Bias Current I
B
Delay to Output (Note 2) T
PD
V
PIN 3
= 0 to 2V
Output Section
2.452.502.552.452.502.55 V
-0.1 -1 -0.1 -0.5 µA
65 90 65 90 dB
0.6 0.6 MHz
60 70 60 70 dB
24 24 mA
-0.5 -0.8 -0.5 -0.8 mA
5 6.5 5 6.5 V
0.7 1.1 0.7 1.1 V
2.85 3 3.152.85 3 3.15 V/V
0.9 1 1.1 0.9 1 1.1 V
70 70 dB
-2 -10 -2 -5 µA
150 300 150 300 ns
0.1 0.4 0.1 0.4 V
1.5 2.2 1.5 2.2 V
13 13.5 13 13.5 V
12 13.5 12 13.5 V
50 100 50 100 ns
50 100 50 100 ns
0.7 1.2 0.7 1.2 V
(Electrical Characteristics continue next page.)
Input Voltage V
PIN 1
= 2.5V
Input Bias Current I
B
Open Loop Gain A
VOL
2 ≤ V
O
≤ 4V
Unity Gain Bandwidth (Note 2) UGBW T
A
= 25°C
Power Supply Rejection Ratio (Note 3) PSRR 12 ≤ V
CC
≤ 25V
Output Sink Current I
OL
V
PIN 2
= 2.7V, V
PIN 1
= 1.1V
Output Source Current I
OH
V
PIN 2
= 2.3V, V
PIN 1
= 5V
Output Voltage High Level V
OH
V
PIN 2
= 2.3V, R
L
= 15K to ground
Output Voltage Low Level V
OL
V
PIN 2
= 2.7V, R
L
= 15K to V
REF
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18

LX1555CDM

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Buy LX1555CDM
Manufacturer:
Microchip / Microsemi
Description:
IC REG CTRLR BUCK/BOOST 8SOIC
Lifecycle:
New from this manufacturer.
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