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LT1533CS#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
1
LT1533
Ultralow Noise
1A Switching Regulator
FEATURES
DESCRIPTION
U
The LT
®
1533 is a new class of switching regulator designed
to reduce conducted and radiated electromagnetic interfer-
ence (EMI). Ultralow noise and EMI are achieved by providing
user control of the output switch slew rates. Voltage and
current slew rates can be independently programmed to
optimize switcher harmonic content versus efficiency. The
LT1533 can reduce high frequency harmonic power by as
much as 40dB with only minor losses in efficiency.
The LT1533 utilizes a dual output switch current mode
architecture optimized for low noise topologies. The IC
includes two 1A power switches along with all necessary
oscillator, control and protection circuitry. Unique error amp
circuitry can regulate both positive and negative voltages.
The internal oscillator may be synchronized to an external
clock for more accurate placement of switching harmonics.
Protection features include cycle by cycle current limit pro-
tection, undervoltage lockout and thermal shutdown.
Low minimum supply voltage and low supply current during
shutdown make the LT1533 well suited for portable applica-
tions. The part may also be forced into a 50% duty cycle mode
for unregulated applications. The LT1533 is available in the
16-pin narrow SO package.
■
Greatly Reduced Conducted and Radiated EMI
(<100
µ
V
P-P
in Typical Application)
■
Low Switching Harmonic Content
■
Independent Control of Switch Voltage and
Current Slew Rates
■
Two 1A Current Limited Power Switches
■
Regulates Positive and Negative Voltages
■
20kHz to 250kHz Oscillator Frequency
■
Easily Synchronized to External Clock
■
Wide Input Voltage Range: 2.7V to 23V
■
Low Shutdown Current: 12µA Typical
■
Easier Layout than with Conventional Switchers
■
Outputs Can Be Forced to 50% Duty Cycle for
Unregulated Applications
■
Precision Instrumentation Systems
■
Isolated Supplies for Industrial Automation
■
Medical Instruments
■
Wireless Communications
■
Single Board Data Acquisition Systems
APPLICATIONS
U
TYPICAL APPLICATION
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
SHDN
DUTY
SYNC
COL A
COL B
PGND
R
VSL
R
CSL
FB
NFB
LT1533
GND
V
IN
5V
14
2
15
16
13
12
7
11
3
4
5
6
10
820pF
16.9k
0.015µF 1000pF
15k
Note 1
33µF
15k
15k
+
T1
1N4148
B
A
L1
300µH
L2
33µH
1N4148
2.49k
1%
89
21.5k, 1%
C1
47µF
16V
+
C2
33µF
20V
C1: SANYO OS-CON
C2: AVX TPS TANTALUM
L1: COILTRONICS CTX300-2
L2: COILCRAFT DT1608C-333
T1: COILTRONICS CTX02-13834
NOTE 1: 25nH TRACE INDUCTANCE 
 OR COILCRAFT B07T
12V
150mA
1533 TA01
+
C
T
R
T
V
C
Low Noise 5V to 12V Forward Push-Pull DC/DC Converter
B
2mV/DIV
A
100µV/DIV
2µs/DIV
1533 TA02
12V Output Noise (BW = 100MHz)
<100µV
P-P
2
LT1533
ABSOLUTE MAXIMUM RATINGS
W
WW
U
(Note 1)
Input Voltage (V
IN
) .................................................. 30V
Switch Voltage (COL A, COL B) ............................... 30V
SHDN Pin Voltage.................................................... 30V
Feedback Pin Current............................................ 10mA
Negative Feedback Pin Current ............................ ±10mA
Storage Temperature Range ................. –65°C to 150°C
Maximum Junction Temperature ......................... 125°C
Operating Junction Temperature Range
LT1533C............................................... 0°C to 100°C
LT1533I ............................................ –40°C to 100°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LT1533CS
LT1533IS
PACKAGE/ORDER INFORMATION
W
U
U
ELECTRICAL CHARACTERISTICS
V
IN
= 5V, V
C
= 0.9V, V
FB
= V
REF
. COL A, COL B, SHDN, NFB, DUTY pins open, unless otherwise noted.
Consult factory for Military grade parts.
TOP VIEW
S PACKAGE
16-LEAD NARROW PLASTIC SO
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
COL A
DUTY
SYNC
C
T
R
T
FB
NFB
PGND
COL B
V
IN
R
VSL
R
CSL
SHDN
V
C
GND
T
JMAX
= 125°C, θ
JA
= 100°C/ W
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Supply and Protection
V
IN
Recommended Operating Range ● 2.7 23 V
V
IN(MIN)
Minimum Input Voltage ● 2.55 2.7 V
I
VIN
Supply Current 2.7V ≤ V
IN
≤ 23V, R
VSL
, R
CSL
, R
T
= 17k ● 12 18 mA
I
VIN(OFF)
Shutdown Supply Current 2.7V ≤ V
IN
≤ 23V, V
SHDN
= 0V ● 12 30 µA
V
SHDN
Shutdown Threshold 2.7V ≤ V
IN
≤ 23V ● 0.4 0.8 1.2 V
I
SHDN
Shutdown Input Current –2 µA
Error Amplifiers
V
REF
Reference Voltage Measured at Feedback Pin 1.235 1.250 1.265 V
● 1.215 1.250 1.275 V
I
FB
Feedback Input Current V
FB
= V
REF
● 250 900 nA
FB
REG
Reference Voltage Line Regulation 2.7V ≤ V
IN
≤ 23V ● 0.003 0.03 %/V
V
NFR
Negative Feedback Reference Voltage Measured at Negative Feedback Pin with ● –2.550 –2.500 –2.420 V
Feedback Pin Open
I
NFR
Negative Feedback Input Current V
NFB
= V
NFR
● –37 –25 µA
NFB
REG
Negative Feedback Reference Voltage 2.7V ≤ V
IN
≤ 23V ● 0.002 0.05 %/V
Line Regulation
3
LT1533
ELECTRICAL CHARACTERISTICS
V
IN
= 5V, V
C
= 0.9V, V
FB
= V
REF
. COL A, COL B, SHDN, NFB, DUTY pins open, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
g
m
Error Amplifier Transconductance ∆I
C
= ±25µA 1100 1500 1900 µmho
● 700 2300 µmho
I
ESK
Error Amplifier Sink Current V
FB
= V
REF
+ 150mV, V
C
= 0.9V, V
SHDN
= 1V ● 120 200 350 µA
I
ESRC
Error Amplifier Source Current V
FB
= V
REF
– 150mV, V
C
= 0.9V, V
SHDN
= 1V ● 120 200 350 µA
V
CLH
Error Amplifier Clamp Voltage High Clamp, V
FB
= 1V 1.33 V
V
CLL
Error Amplifier Clamp Voltage Low Clamp, V
FB
= 1.5V 0.1 V
A
V
Error Amplifier Voltage Gain 180 250 V/V
Oscillator and Sync
f
MAX
Maximum Switch Frequency 250 kHz
f
SYNC
Synchronization Frequency Range f
OSC
= 250kHz ● 375 kHz
R
SYNC
SYNC Pin Input Resistance 40 kΩ
V
FBfs
FB Pin Threshold for Frequency Shift 5% Reduction from Nominal 0.4 V
Output Switches
DC
MAX
Maximum Switch Duty Cycle DUTY Pin Open, R
VSL
= R
CSL
= 4.9k, f
OSC
= 25kHz ● 44 45.5 %
DUTY Pin Grounded, Forced 50% Duty Cycle 50.0 %
t
IBL
Switch Current Limit Blanking Time 200 ns
BV Output Switch Breakdown Voltage 2.7V ≤ V
IN
≤ 23V ● 25 30 V
R
ON
Output Switch-On Resistance I
COL A
or I
COL B
= 0.75A ● 0.5 0.85 Ω
I
LIM(MAX)
Maximum Current Limit Duty Cycle = 15% 1 1.25 1.8 A
Short-Circuit Current Limit Duty Cycle = 40% 0.8 A
∆I
IN
/∆I
SW
Supply Current Increase During 16 mA/A
Switch-On Time
V
DUTYTH
DUTY Pin Threshold 0.35
Slew Control
V
SLEWR
Output Voltage Slew Rising Edge Either A or B, R
VSL
, R
CSL
= 17k 11 V/µs
V
SLEWF
Output Voltage Slew Falling Edge Either A or B, R
VSL
, R
CSL
= 17k 14.5 V/µs
I
SLEWR
Output Current Slew Rising Edge Either A or B, R
VSL
, R
CSL
= 17k 1.3 A/µs
I
SLEWF
Output Current Slew Falling Edge Either A or B, R
VSL
, R
CSL
= 17k 1.3 A/µs
The ● denotes specifications that apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LT1533 is designed to operate over the junction temperature
range of –40°C to 125°C, but is neither tested nor guaranteed beyond 0°C
to 100°C for C grade or –40°C to 100°C for I grade.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

LT1533CS#PBF

Mfr. #:
Buy LT1533CS#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Ultralow N 1A Sw Reg
Lifecycle:
New from this manufacturer.
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