LT1534/LT1534-1
Ultralow Noise
2A Switching Regulators
FEATURES
s
s
s
DESCRIPTIO
s
s
s
s
s
s
s
Greatly Reduced Conducted and Radiated EMI
Low Switching Harmonic Content
Independent Control of Switch Voltage and
Current Slew Rates
2A Current Limited Power Switch
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
APPLICATIO S
s
s
s
s
s
Precision Instrumentation Systems
Isolated Supplies for Industrial Automation
Medical Instruments
Wireless Communications
Single Board Data Acquisition Systems
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
3.3V
L1
50µH
1N5817
A
L3
50µH
C1
47µF
6.3V
×2
B
+
C
IN
33µF
6.3V
15
12
4
SHDN
SYNC
PGND
LT1534-1
R
VSL
R
T
R
CSL
11
V
C
GND
1,8,
9,16
NFB
FB
3
14
13
7
2.49k
24k
24k
V
IN
COL
2
10Ω
+
L2
1nF
+
OPTIONAL
5V
650mA
C2
47µF
3300pF
5
16.9k 6
C
T
A
50mV/DIV
7.5k
1534 TA01
220pF
6.8k
15nF
10
C
IN
: MATSUSHITA ECGCOJB330
C1, C2: MATSUSHITA ECGCOJB47O
L1, L3: COILTRONICS CTX50-4
L2: COILCRAFT B08T (28nH) OR PC TRACE
B
2mV/DIV
Figure 1. Low Noise 3.3V to 5V Boost Converter
U
5V Output Noise (BW = 100MHz)
10µs/DIV
1534 TA02
U
U
1
LT1534/LT1534-1
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
Input Voltage (V
IN
) .................................................. 30V
Switch Voltage (COL) .............................................. 35V
SHDN Pin Voltage .................................................... 30V
Feedback Pin Current (FB) .................................... 10mA
Negative Feedback Pin Current (NFB) ..................
±10mA
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
PACKAGE/ORDER INFORMATION
TOP VIEW
NC 1
COL 2
*NC 3
SYNC 4
C
T
5
R
T
6
FB 7
NFB 8
16 PGND
15 COL
14 V
IN
13 R
VSL
12 R
CSL
11 SHDN
10 V
C
9
GND
ORDER PART
NUMBER
GND 1
LT1534CS
LT1534IS
S PACKAGE
16-LEAD PLASTIC SO
*DO NOT CONNECT
T
JMAX
= 125°C,
θ
JA
= 100°C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN
V
IN(MIN)
I
VIN
I
VIN(OFF)
V
SHDN
I
SHDN
V
REF
I
FB
FB
REG
PARAMETER
Recommended Operating Range
Minimum Input Voltage
Operating Supply Current
Shutdown Supply Current
Shutdown Threshold
Shutdown Input Current
Reference Voltage
Feedback Input Current
Reference Voltage Line Regulation
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.
CONDITIONS
q
q
Supply and Protection
2.7
2.55
12
12
12
0.4
0.8
–2
Measured at Feedback Pin
q
2.7V
≤
V
IN
≤
23V, R
VSL
, R
CSL
, R
T
= 17k
2.7V
≤
V
IN
≤
23V, V
SHDN
= 0V
2.7V
≤
V
IN
≤
23V, V
SHDN
= 0V
2.7V
≤
V
IN
≤
23V
Error Amplifiers
1.235
1.215
1.250
1.250
250
0.003
1.265
1.275
900
0.03
V
V
nA
%/V
V
FB
= V
REF
2.7V
≤
V
IN
≤
23V
2
U
U
W
W W
U
W
TOP VIEW
16 GND
15 V
IN
14 R
VSL
13 R
CSL
12 SHDN
11 V
C
10 NFB
9
GND
ORDER PART
NUMBER
LT1534CS-1
LT1534IS-1
COL 2
PGND 3
SYNC 4
C
T
5
R
T
6
FB 7
GND 8
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.
T
JMAX
= 125°C,
θ
JA
= 50°C/ W
MIN
TYP
MAX
23
2.7
30
50
30
1.2
UNITS
V
V
mA
µA
µA
V
µA
q
q
q
q
q
LT1534/LT1534-1
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.
SYMBOL
V
NFR
I
NFR
NFB
REG
g
m
I
ESK
I
ESRC
V
CLH
V
CLL
A
V
f
MAX
f
SYNC
R
SYNC
V
FBfs
DC
MAX
t
IBL
BV
COL
R
ON
I
LIM
∆I
IN
/∆I
SW
Slew Control
V
SLEWR
V
SLEWF
I
SLEWR
I
SLEWF
Output Voltage Slew Rising Edge
Output Voltage Slew Falling Edge
Output Current Slew Rising Edge
Output Current Slew Falling Edge
R
VSL
, R
CSL
= 17k
R
VSL
, R
CSL
= 17k
R
VSL
, R
CSL
= 17k
R
VSL
, R
CSL
= 17k
11
14.5
1.3
1.3
V/µs
V/µs
A/µs
A/µs
PARAMETER
Negative Feedback Reference Voltage
Negative Feedback Input Current
Negative Feedback Reference Voltage
Line Regulation
Error Amplifier Transconductance
Error Amplifier Sink Current
Error Amplifier Source Current
Error Amplifier Clamp Voltage
Error Amplifier Clamp Voltage
Error Amplifier Voltage Gain
Maximum Switch Frequency
Synchronization Frequency Range
SYNC Pin Input Resistance
FB Pin Threshold for Frequency Shift
Maximum Switch Duty Cycle
Switch Current Limit Blanking Time
Output Switch Breakdown Voltage
Output Switch-On Resistance
Switch Current Limit
Supply Current Increase During
Switch-On Time
2.7V
≤
V
IN
≤
23V
I
COL
= 1.5A, Both COL Pins Tied Together
Duty Cycle = 30%
Duty Cycle = 80%
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
Measured at Negative Feedback Pin with
Feedback Pin Open
V
NFB
= V
NFR
2.7V
≤
V
IN
≤
23V
∆I
C
=
±25µA
q
q
q
q
MIN
– 2.550
– 37
TYP
– 2.500
– 25
0.002
MAX
– 2.420
UNITS
V
µA
Error Amplifiers
0.05
1900
2300
350
350
%/V
µmho
µmho
µA
µA
V
V
V/V
kHz
1100
700
120
120
1500
200
200
1.33
0.1
V
FB
= V
REF
+ 150mV, V
C
= 0.9V, V
SHDN
= 1V
V
FB
= V
REF
– 150mV, V
C
= 0.9V, V
SHDN
= 1V
High Clamp, V
FB
= 1V
Low Clamp, V
FB
= 1.5V
q
q
180
250
250
Oscillator and Sync
f
OSC
= 250kHz
5% Reduction from Nominal
R
VSL
= R
CSL
= 4.9k, f
OSC
= 25kHz
q
q
375
40
0.4
88
35
0.25
2
1.6
16
0.43
91
200
kHz
kΩ
V
%
ns
V
Ω
A
A
mA/A
Output Switches
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
3
LT1534/LT1534-1
TYPICAL PERFORMANCE CHARACTERISTICS
Minimum Input Voltage (V
IN
)
vs Temperature
2.70
2.65
SWITCH VOLTAGE (V)
INPUT VOLTAGE (V)
2.60
∆I
LIM
(mA)
2.55
2.50
2.45
–50 –25
25 50
0
75 100 125 150
JUNCTION TEMPERATURE (°C)
1534 G01
Feedback Voltage and
Input Current vs Temperature
1.30
1.29
1.28
2.0
1.8
–2.30
–2.35
NEGATIVE FB VOLTAGE (V)
FEEDBACK VOLTAGE (V)
1.27
1.26
1.25
1.24
1.23
1.22
1.21
1.20
–50 –25
0
I
FB
V
FB
0
25 50 75 100 125 150
TEMPERATURE (°C)
1533 G04
Error Amplifier Transconductance
vs Temperature
2000
SWITCHING FREQUENCY (% TYPICAL)
1900
g
m
=
∆I
VC
/∆V
FB
TRANSCONDUCTANCE (mho)
1800
1700
1600
1500
1400
1300
1200
1100
1000
–50 –25
0
25
50
75
100 125 150
1534 G08
ERROR AMPLIFIER OUTPUT (µA)
TEMPERATURE (°C)
4
U W
Change in Maximum Switch
Current (I
LIM
) vs Duty Cycle
0
–100
25°C
– 200
125°C
– 300
– 400
– 500
– 600
85°C
0.8
0.7
Output Switch Saturation Voltage
vs Switch Current
150°C
0.6
85°C
0.5
0.4
– 40°C
0.3
0.2
0.1
0
0
1.0
0.5
1.5
SWITCH CURRENT (A)
2.0
1534 G03
25°C
0
20
40
60
DUTY CYCLE (%)
80
100
1533 G02
Negative Feedback Voltage and
Input Current vs Temperature
35
FEEDBACK INPUT CURRENT (µA)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
NFB IINPUT CURRENT (µA)
–2.40
–2.45
–2.50
–2.55
–2.60
–2.65
–2.70
–50 –25
0
I
NFB
V
NFB
30
25
20
15
25 50 75 100 125 150
TEMPERATURE (°C)
1533 G05
Switching Frequency vs
Feedback Pin Voltage
100
90
80
70
60
50
40
30
20
10
0
0
0.1
0.3
0.4
0.5
0.2
FEEDBACK PIN VOLTAGE (V)
0.6
1533 G06
Error Amplifier Output Current (V
C
)
500
400
300
200
100
0
–100
–200
–300
–400
–500
–400 –300 –200 –100 0 100 200 300 400
FEEDBACK PIN VOLTAGE FROM NOMINAL (mV)
1534 G07
T
A
= 25°C
–40°C
125°C
25°C
LT1534/LT1534-1
TYPICAL PERFORMANCE CHARACTERISTICS
V
C
Pin Threshold and Clamp
Voltage vs Temperature
1.6
1.4
V
C
PIN VOLTAGE (V)
1.2
1.0
0.8
0.6
0.4
0.2
0
–50 –25
0
V
C
PIN CLAMP
VOLTAGE
V
C
PIN
THRESHOLD
25
TEMPERATURE (°C)
1534 G09
Typical Output Switch Voltage
and Current Slew Rates vs Slew
Setting Resistance (R
VSL
= R
CSL
)
40
35
I
RISE
I
FALL
V
RISE
V
FALL
2
3
T
A
= 25°C
4
2.0
1.5
VOLTAGE SLEW (V/µs)
30
25
20
15
10
5
0
0
CHANGE IN FREQUENCY (%)
1/20k
1/R (mmho)
1534 G11
∆V
OUT
(%)
U W
50
75
1/10k
Load Transient Response
I
LOAD
0.5A/DIV
V
OUT
100mV/DIV
100 125
V
IN
= 3.3V
500µs/DIV
V
OUT
= 5V (NODE A)
I
LOAD
= 0.1A TO 0.5A
FIGURE 1 CIRCUIT
1534 G10
Percent Change in Oscillator
Frequency vs Temperature (NPO
Cap and Metal Film R)
1.0
0.5
0
–0.5
–1.0
–1.5
CURRENT SLEW (A/µs)
1
1/6.7k
0
1/5k
–2.0
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
1534 G12
Load Regulation
2.0
FIGURE 1 CIRCUIT
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
0
100
200 300 400 500
LOAD CURRENT (mA)
600
700
1534-1 G13
5
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