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1
LT1534/LT1534-1
TYPICAL APPLICATIO
N
U
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
Ultralow Noise
2A Switching Regulators
The LT
1534/LT1534-1 are a new class of switching regula-
tor designed to reduce conducted and radiated electromag-
netic interference (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 pro-
grammed to optimize switcher harmonic content versus
efficiency. The LT1534/LT1534-1 can reduce high frequency
harmonic power by as much as 40dB with only minor losses
in efficiency.
The LT1534/LT1534-1 utilize a current mode architecture
optimized for low noise boost topologies. The ICs include a
2A power switch 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 fea-
tures include cycle-by-cycle current limit protection, under-
voltage lockout and thermal shutdown.
Low minimum supply voltage and low supply current during
shutdown make the LT1534/LT1534-1 well suited for por-
table applications. The LT1534/LT1534-1 are available in the
16-pin narrow SO package.
s
Greatly Reduced Conducted and Radiated EMI
s
Low Switching Harmonic Content
s
Independent Control of Switch Voltage and
Current Slew Rates
s
2A Current Limited Power Switch
s
Regulates Positive and Negative Voltages
s
20kHz to 250kHz Oscillator Frequency
s
Easily Synchronized to External Clock
s
Wide Input Voltage Range: 2.7V to 23V
s
Low Shutdown Current: 12
A Typical
s
Easier Layout than with Conventional Switchers
, LTC and LT are registered trademarks of Linear Technology Corporation.
s
Precision Instrumentation Systems
s
Isolated Supplies for Industrial Automation
s
Medical Instruments
s
Wireless Communications
s
Single Board Data Acquisition Systems
B
2mV/DIV
A
50mV/DIV
10
s/DIV
1534 TA02
5V Output Noise (BW = 100MHz)
SHDN
SYNC
COL
NFB
LT1534-1
GND
V
IN
3.3V
15
2
PGND
3
L2
R
VSL
14
R
CSL
13
7
12
4
5
6
11
3300pF
16.9k
220pF
1nF
24k
C
IN
33
F
6.3V
10
24k
+
1N5817
A
OPTIONAL
L1
50
H
2.49k
6.8k
10
1,8,
9,16
7.5k
C1
47
F
6.3V
2
+
C
IN
: MATSUSHITA ECGCOJB330
C1, C2: MATSUSHITA ECGCOJB47O
L1, L3: COILTRONICS CTX50-4
L2: COILCRAFT B08T (28nH) OR PC TRACE
1534 TA01
C
T
R
T
V
C
FB
L3
50
H
C2
47
F
5V
650mA
+
15nF
B
Figure 1. Low Noise 3.3V to 5V Boost Converter
2
LT1534/LT1534-1
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
Input Voltage (V
IN
) .................................................. 30V
Switch Voltage (COL) .............................................. 35V
SHDN Pin Voltage .................................................... 30V
Feedback Pin Current (FB) .................................... 10mA
Negative Feedback Pin Current (NFB) ..................
10mA
ELECTRICAL CHARACTERISTICS
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
ORDER PART
NUMBER
LT1534CS
LT1534IS
TOP VIEW
S PACKAGE
16-LEAD PLASTIC SO
*DO NOT CONNECT
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
COL
*NC
SYNC
C
T
R
T
FB
NFB
PGND
COL
V
IN
R
VSL
R
CSL
SHDN
V
C
GND
Consult factory for Military grade parts.
T
JMAX
= 125
C,
JA
= 100
C/ W
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Supply and Protection
V
IN
Recommended Operating Range
q
2.7
23
V
V
IN(MIN)
Minimum Input Voltage
q
2.55
2.7
V
I
VIN
Operating Supply Current
2.7V
V
IN
23V, R
VSL
, R
CSL
, R
T
= 17k
q
12
30
mA
I
VIN(OFF)
Shutdown Supply Current
2.7V
V
IN
23V, V
SHDN
= 0V
q
12
50
A
2.7V
V
IN
23V, V
SHDN
= 0V
12
30
A
V
SHDN
Shutdown Threshold
2.7V
V
IN
23V
q
0.4
0.8
1.2
V
I
SHDN
Shutdown Input Current
2
A
Error Amplifiers
V
REF
Reference Voltage
Measured at Feedback Pin
1.235
1.250
1.265
V
q
1.215
1.250
1.275
V
I
FB
Feedback Input Current
V
FB
= V
REF
q
250
900
nA
FB
REG
Reference Voltage Line Regulation
2.7V
V
IN
23V
q
0.003
0.03
%/V
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C, V
IN
= 5V, V
C
= 0.9V, V
FB
= V
REF
. COL, SHDN, NFB, all other pins open
unless otherwise noted.
(Note 1)
Operating Junction Temperature Range
LT1534C ................................................ 0
C to 125
C
LT1534I ............................................ 40
C to 125
C
Maximum Junction Temperature .......................... 125
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec.)................. 300
C
ORDER PART
NUMBER
LT1534CS-1
LT1534IS-1
T
JMAX
= 125
C,
JA
= 50
C/ W
TOP VIEW
S PACKAGE
16-LEAD PLASTIC SO
**FOUR CORNER PINS ARE FUSED TO INTERNAL
DIE ATTACH PADDLE FOR HEAT SINKING.
CONNECT THESE FOUR PINS TO EXPANDED
PC LANDS FOR PROPER HEAT SINKING.
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
GND
COL
PGND
SYNC
C
T
R
T
FB
GND
GND
V
IN
R
VSL
R
CSL
SHDN
V
C
NFB
GND
3
LT1534/LT1534-1
ELECTRICAL CHARACTERISTICS
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C, V
IN
= 5V, V
C
= 0.9V, V
FB
= V
REF
. COL, SHDN, NFB, all other pins open
unless otherwise noted.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Error Amplifiers
V
NFR
Negative Feedback Reference Voltage
Measured at Negative Feedback Pin with
q
2.550
2.500
2.420
V
Feedback Pin Open
I
NFR
Negative Feedback Input Current
V
NFB
= V
NFR
q
37
25
A
NFB
REG
Negative Feedback Reference Voltage
2.7V
V
IN
23V
q
0.002
0.05
%/V
Line Regulation
g
m
Error Amplifier Transconductance
I
C
=
25
A
1100
1500
1900
mho
q
700
2300
mho
I
ESK
Error Amplifier Sink Current
V
FB
= V
REF
+ 150mV, V
C
= 0.9V, V
SHDN
= 1V
q
120
200
350
A
I
ESRC
Error Amplifier Source Current
V
FB
= V
REF
150mV, V
C
= 0.9V, V
SHDN
= 1V
q
120
200
350
A
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
q
375
kHz
R
SYNC
SYNC Pin Input Resistance
40
k
V
FBfs
FB Pin Threshold for Frequency Shift
5% Reduction from Nominal
0.4
V
Output Switches
DC
MAX
Maximum Switch Duty Cycle
R
VSL
= R
CSL
= 4.9k, f
OSC
= 25kHz
q
88
91
%
t
IBL
Switch Current Limit Blanking Time
200
ns
BV
COL
Output Switch Breakdown Voltage
2.7V
V
IN
23V
q
35
V
R
ON
Output Switch-On Resistance
I
COL
= 1.5A, Both COL Pins Tied Together
q
0.25
0.43
I
LIM
Switch Current Limit
Duty Cycle = 30%
2
A
Duty Cycle = 80%
1.6
A
I
IN
/
I
SW
Supply Current Increase During
16
mA/A
Switch-On Time
Slew Control
V
SLEWR
Output Voltage Slew Rising Edge
R
VSL
, R
CSL
= 17k
11
V/
s
V
SLEWF
Output Voltage Slew Falling Edge
R
VSL
, R
CSL
= 17k
14.5
V/
s
I
SLEWR
Output Current Slew Rising Edge
R
VSL
, R
CSL
= 17k
1.3
A/
s
I
SLEWF
Output Current Slew Falling Edge
R
VSL
, R
CSL
= 17k
1.3
A/
s
4
LT1534/LT1534-1
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
Minimum Input Voltage (V
IN
)
vs Temperature
JUNCTION TEMPERATURE (
C)
INPUT VOLTAGE (V)
2.60
2.65
2.70
1534 G01
2.55
2.50
2.45
50
0
50
75
25
25
100 125
150
SWITCH CURRENT (A)
0
SWITCH VOLTAGE (V)
0.4
0.6
2.0
1534 G03
0.2
0
0.5
1.0
1.5
0.8
0.3
0.5
0.1
0.7
150
C
85
C
25
C
40
C
Output Switch Saturation Voltage
vs Switch Current
DUTY CYCLE (%)
0
I
LIM
(mA)
0
100
200
300
400
500
600
20
40
60
25
C
80
1533 G02
100
125
C
85
C
Change in Maximum Switch
Current (I
LIM
) vs Duty Cycle
Negative Feedback Voltage and
Input Current vs Temperature
TEMPERATURE (
C)
50
NEGATIVE FB VOLTAGE (V)
NFB IINPUT CURRENT (
A)
150
1533 G05
0
50
100
2.30
2.35
2.40
2.45
2.50
2.55
2.60
2.65
2.70
35
30
25
20
15
25
25
75
125
V
NFB
I
NFB
Feedback Voltage and
Input Current vs Temperature
TEMPERATURE (
C)
50
FEEDBACK VOLTAGE (V)
FEEDBACK INPUT CURRENT (
A)
1.30
1.29
1.28
1.27
1.26
1.25
1.24
1.23
1.22
1.21
1.20
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
50
75
1533 G04
25
25
V
FB
I
FB
100 125
150
Switching Frequency vs
Feedback Pin Voltage
FEEDBACK PIN VOLTAGE (V)
0
SWITCHING FREQUENCY (% TYPICAL)
0.1
0.2
0.3
0.4
1533 G06
0.5
100
90
80
70
60
50
40
30
20
10
0
0.6
T
A
= 25
C
FEEDBACK PIN VOLTAGE FROM NOMINAL (mV)
400 300 200 100
ERROR AMPLIFIER OUTPUT (
A)
400
1534 G07
0
100
300
200
500
400
300
200
100
0
100
200
300
400
500
125
C
40
C
25
C
Error Amplifier Output Current (V
C
)
TEMPERATURE (
C)
TRANSCONDUCTANCE (mho)
1534 G08
2000
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
50
25
75
150
25
0
50
100 125
g
m
=
I
VC
/
V
FB
Error Amplifier Transconductance
vs Temperature
5
LT1534/LT1534-1
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
V
IN
= 3.3V
500
s/DIV
1534 G10
V
OUT
= 5V (NODE A)
I
LOAD
= 0.1A TO 0.5A
FIGURE 1 CIRCUIT
I
LOAD
0.5A/DIV
V
OUT
100mV/DIV
Load Transient Response
TEMPERATURE (
C)
V
C
PIN VOLTAGE (V)
1534 G09
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
50
25
75
25
0
50
100 125
V
C
PIN CLAMP
VOLTAGE
V
C
PIN
THRESHOLD
V
C
Pin Threshold and Clamp
Voltage vs Temperature
Percent Change in Oscillator
Frequency vs Temperature (NPO
Cap and Metal Film R)
Typical Output Switch Voltage
and Current Slew Rates vs Slew
Setting Resistance (R
VSL
= R
CSL
)
TEMPERATURE (
C)
CHANGE IN FREQUENCY (%)
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
1534 G12
50
0
50
75
25
25
100
125
1/R (mmho)
VOLTAGE SLEW (V/
s)
CURRENT SLEW (A/
s)
40
35
30
25
20
15
10
5
0
4
3
2
1
0
1534 G11
0
1/20k
1/10k
1/6.7k
1/5k
V
FALL
V
RISE
I
FALL
I
RISE
T
A
= 25
C
Load Regulation
LOAD CURRENT (mA)
V
OUT
(%)
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
1534-1 G13
0
200
400
500
100
300
600
700
FIGURE 1 CIRCUIT
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