LTC1530
High Power Synchronous
Switching Regulator Controller
FEATURES
s
s
DESCRIPTIO
s
s
s
s
s
s
s
s
s
s
High Power Buck Converter from 5V or 3.3V
Main Power
Adjustable Current Limit in S0-8 with
Topside FET R
DS(ON)
Sensing
No External Sense Resistor Required
Hiccup Mode Current Limit Protection
Adjustable, Fixed 1.9V, 2.5V, 2.8V and 3.3V Output
All N-Channel MOSFET Synchronous Driver
Excellent Output Regulation:
±2%
over Line, Load
and Temperature Variations
High Efficiency: Over 95% Possible
Fast Transient Response
Fixed 300kHz Frequency Operation
Internal Soft-Start Circuit
Quiescent Current: 1mA, 45µA in Shutdown
The LTC
®
1530 is a high power synchronous switching
regulator controller optimized for 5V to 1.3V-3.5V output
applications. Its synchronous switching architecture drives
two external N-channel MOSFET devices to provide high
efficiency. The LTC1530 contains a precision trimmed
reference and feedback system that provides worst-case
output voltage regulation of
±2%
over temperature, load
current and line voltage shifts. Current limit circuitry
senses the output current through the on-resistance of
the topside N-channel MOSFET, providing an adjustable
current limit without requiring an external low value sense
resistor.
The LTC1530 includes a fixed frequency PWM oscillator
that free runs at 300kHz, providing greater than 90%
efficiency in converter designs from 1A to 20A of output
current. Shutdown mode drops the LTC1530 supply cur-
rent to 45µA.
The LTC1530 is specified for commercial and industrial
temperature ranges and is available in the S0-8 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Pentium is a registered trademark of Intel Corp.
AMD-K6 is a registered trademark of Advanced Micro Devices, Inc.
APPLICATIO S
s
s
Power Supply for Pentium
®
II, AMD-K6
®
-2, SPARC,
ALPHA and PA-RISC Microprocessors
High Power 5V to 1.3V-3.5V Regulators
TYPICAL APPLICATIO
+
V
IN
5V
100
MBR0530T1 MBR0530T1
0.1µF
2.7k
+
10µF
0.22µF
L
O†
2µH
90
C
IN
**
1200µF
×
4
EFFICIENCY (%)
80
70
60
50
40
30
1530 F01a
I
MAX
PV
CC
C1
150pF
C
C
0.022µF
R
C
10k
G1
20Ω
Q1*
I
FB
COMP
LTC1530-3.3
G2
GND
V
OUT
†
COILTRONICS CTX02-13198
+
Q2*
C
O††
330µF
×
7
V
OUT
3.3V
14A
20
10
T
A
= 25°C
0
0.3
2
8
4
10
6
LOAD CURRENT (A)
12
14
OR PANASONIC ETQP6F2R5HA
††
AVX TPSE337M006R0100
* SILICONIX SUD50N03-10
** SANYO 10MV1200GX
COILTRONICS (561) 241-7876
Figure 1. Single 5V to 3.3V Supply
U
Efficiency vs Load Current
0
1530 F01b
U
U
1
LTC1530
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
PV
CC
1
GND 2
*V
SENSE
/
V
OUT
3
COMP 4
8
7
6
5
G1
G2
I
FB
I
MAX
Supply Voltage
PV
CC
........................................................................ 14V
Input Voltage
I
FB
(Note 2) ............................................... PV
CC
+ 0.3V
I
MAX
........................................................ – 0.3V to 14V
I
FB
Input Current (Notes 2,3) ............................ – 100mA
Operating Ambient Temperature Range
LTC1530C ............................................... 0°C to 70°C
LTC1530I ............................................ – 40°C to 85°C
Maximum Junction Temperature
LTC1530C, LTC1530I ...................................... 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC1530CS8
LTC1530CS8-1.9
LTC1530CS8-2.5
LTC1530CS8-2.8
LTC1530CS8-3.3
LTC1530IS8
LTC1530IS8-1.9
LTC1530IS8-2.5
LTC1530IS8-2.8
LTC1530IS8-3.3
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 130°C/ W
*V
OUT
FOR FIXED VOLTAGE VERSIONS
S8 PART MARKING
1530
153019
153025
153028
153033
1530I
530I19
530I25
530I28
530I33
Consult factory for Military grade parts.
The
q
denotes specifications that apply over the full operating temperature
range, otherwise specifications are at 0°C
≤
T
A
≤
70°C. PV
CC
= 12V unless otherwise noted. (Note 3)
SYMBOL
V
SENSE
V
OUT
PARAMETER
Internal Feedback Voltage
Output Voltage
CONDITIONS
LTC1530CS8 (Note 4)
q
ELECTRICAL CHARACTERISTICS
MIN
1.223
1.216
1.881
1.871
2.475
2.462
2.772
2.758
3.267
3.250
1.6
TYP
1.235
1.235
1.9
1.9
2.5
2.5
2.8
2.8
3.3
3.3
2
MAX
1.247
1.254
1.919
1.929
2.525
2.538
2.828
2.842
3.333
3.350
2.6
UNITS
V
V
V
V
V
V
V
V
V
V
millimho
LTC1530CS8-1.9 (Note 4)
q
LTC1530CS8-2.5 (Note 4)
q
LTC1530CS8-2.8 (Note 4)
q
LTC1530CS8-3.3 (Note 4)
q
g
mERR
Error Amplifier Transconductance
(Note 5)
q
The
q
denotes specifications that apply over the full operating temperature range, otherwise specifications are at –40°C
≤
T
A
≤
85°C.
PV
CC
= 12V unless otherwise noted. (Note 3)
SYMBOL
PV
CC
V
UVLO
V
SENSE
PARAMETER
Supply Voltage
Undervoltage Lockout Voltage
Internal Feedback Voltage
CONDITIONS
(Note 6)
(Note 7)
LTC1530IS8 (Note 4)
q
q
MIN
TYP
3.5
MAX
13.2
3.75
1.247
1.260
UNITS
V
V
V
V
1.223
1.210
1.235
1.235
2
U
W
U
U
W W
W
LTC1530
The
q
denotes specifications that apply over the full operating temperature
range, otherwise specifications are at –40°C
≤
T
A
≤
85°C. PV
CC
= 12V unless otherwise noted. (Note 3)
SYMBOL
V
OUT
PARAMETER
Output Voltage
CONDITIONS
LTC1530IS8-1.9 (Note 4)
q
ELECTRICAL CHARACTERISTICS
MIN
1.881
1.862
2.475
2.450
2.772
2.744
3.267
3.234
TYP
1.9
1.9
2.5
2.5
2.8
2.8
3.3
3.3
–5
±1
15
MAX
1.919
1.938
2.525
2.550
2.828
2.856
3.333
3.366
UNITS
V
V
V
V
V
V
V
V
mV
mV
mA
LTC1530IS8-2.5 (Note 4)
q
LTC1530IS8-2.8 (Note 4)
q
LTC1530IS8-3.3 (Note 4)
q
∆V
OUT
I
PVCC
Output Load Regulation
Output Line Regulation
Operating Supply Current
Quiescent Current
Shutdown Supply Current
I
OUT
= 0 to 14A
V
IN
= 4.75V to 5.25V, I
OUT
= 0
Figure 3, V
FB
= 0V (Note 8)
Figure 3, COMP = 0.5V, V
FB
= 5V
Figure 3, COMP = 0 (Note 9)
Figure 4
V
COMP
at 0% Duty Cycle
V
COMP
at Max Duty Cycle
(Note 5)
(Note 5)
V
IMAX
= 5V
V
IMAX
= 5V
V
IMAX
= 5V
Figure 4, Measured at COMP Pin (Note 9)
Figure 4, COMP Pulls High, V
FB
= 0V
(Notes 9, 10)
Figure 4, COMP Pulls High to G1↑ (Note 10)
Figure 4
Figure 4
Figure 4
q
q
q
q
q
q
q
q
q
q
1.0
45
250
300
2.5
3.5
40
1.6
170
120
100
54
2
200
200
3300
180
0.4
3.5
90
30
81
100
86
1.4
80
350
mA
µA
kHz
V
V
dB
f
OSC
Internal Oscillator Frequency
Oscillator Valley Voltage
Oscillator Peak Voltage
G
ERR
g
mERR
I
MAX
Error Amplifier Open-Loop DC Gain
Error Amplifier Transconductance
I
MAX
Sink Current
I
MAX
Sink Current Tempco
2.8
230
300
millimho
µA
µA
ppm/°C
mV
V/ms
ms
V
SHDN
SR
SS
t
SS
t
r
, t
f
t
NOL
DC
MAX
Shutdown Threshold Voltage
Internal Soft-Start Slew Rate
Internal Soft-Start Wake-Up Time
Driver Rise and Fall Time
Driver Nonoverlap Time
Maximum G1 Duty Cycle
140
ns
ns
%
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
If I
FB
is taken below GND, it is clamped by an internal diode. This
pin handles input currents
≤
100mA below GND without latch-up. In the
positive direction, it is not clamped to PV
CC
.
Note 3:
All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.
Note 4:
The LTC1530 is tested in an op amp feedback loop which
regulates V
SENSE
or V
OUT
based on V
COMP
= 2V for the error amplifier.
Note 5:
The Open-loop DC gain and transconductance from the V
FB
pin to
the COMP pin are G
ERR
and g
mERR
respectively. For fixed output voltage
versions, the actual open-loop DC gain and transconductance are G
ERR
and g
mERR
multiplied by the ratio 1.235/V
OUT
.
Note 6:
The total voltage from the PV
CC
pin to the GND pin must be
≥
8V
for the current limit protection circuit to be active.
Note 7:
G1 and G2 begin to switch once PV
CC
is
≥
the undervoltage
lockout threshold voltage.
Note 8:
Supply current in normal operation is dominated by the current
needed to charge and discharge the external FET gates. This current varies
with the LTC1530 operating frequency, supply voltage and the external
FETs used.
Note 9:
The LTC1530 enters shutdown if COMP is pulled low.
Note 10:
Slew rate is measured at the COMP pin on the transition from
shutdown to active mode.
3
LTC1530
TYPICAL PERFOR A CE CHARACTERISTICS
Efficiency vs Load Current
100
90
80
2.510
2.508
2.506
T
A
= 25°C
REFER TO FIGURE 2
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
0.3
2
8
10
4
6
LOAD CURRENT (A)
12
14
T
A
= 25°C
REFER TO FIGURE 10
OUTPUT VOLTAGE (V)
2.500
2.498
2.496
2.494
2.492
2.490
0
1
2
3
4
OUTPUT CURRENT (A)
5
6
1530 G02
V
SENSE
(V)
LTC1530-1.9 V
OUT
vs Temperature
1.930
1.925
1.920
1.915
1.910
V
OUT
(V)
V
OUT
(V)
V
OUT
(V)
1.905
1.900
1.895
1.890
1.885
1.880
1.875
1.870
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G04
ERROR AMPLIFIER TRANSCONDUCTANCE (millimho)
LTC1530-3.3 V
OUT
vs Temperature
3.36
3.35
3.34
3.33
3.32
3.31
3.30
3.29
3.28
3.27
3.26
3.25
3.24
3.23
–55 –35 –15
UNDERVOLTAGE LOCKOUT THRESHOLD (V)
V
OUT
(V)
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G06
4
U W
Load Regulation
1.260
1.255
1.250
1.245
1.240
1.235
1.230
1.225
1.220
1.215
LTC1530 V
SENSE
vs Temperature
2.504
2.502
1.210
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G03
1530 G01
LTC1530-2.5 V
OUT
vs Temperature
2.55
2.54
2.53
2.52
2.51
2.50
2.49
2.48
2.47
2.46
2.45
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G05
LTC1530-2.8 V
OUT
vs Temperature
2.85
2.84
2.83
2.82
2.81
2.80
2.79
2.78
2.77
2.76
2.75
2.74
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G06
Undervoltage Lockout Threshold
Voltage vs Temperature
4.5
4.3
4.1
3.9
3.7
3.5
3.3
3.1
2.9
2.7
2.5
2.3
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G08
Error Amplifier Transconductance
vs Temperature
2.8
2.6
2.4
2.2
2.0
1.8
1.6
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G09
LTC1530
TYPICAL PERFOR A CE CHARACTERISTICS
Error Amplifier Open-Loop Gain
vs Temperature
ERROR AMPLIFIER OPEN-LOOP DC GAIN (dB)
60
OSCILLATOR FREQUENCY (kHz)
55
330
320
310
300
290
280
270
260
MAXIMUM G1 DUTY CYCLE (%)
50
45
40
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G10
I
MAX
Sink Current vs Temperature
300
280
I
MAX
SINK CURRENT (µA)
70
PV
CC
SHUTDOWN CURRENT (µA)
PV
CC
= 12V
G1, G2 ARE NOT SWITCHING
PV
CC
SUPPLY CURRENT (mA)
260
240
220
200
180
160
140
120
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G13
Shutdown Threshold Voltage
vs Temperature
250
3.0
PV
CC
= 12V
MEASURED AT
COMP PIN
2.5
SHUTDOWN THRESHOLD VOLTAGE (mV)
200
OUTPUT VOLTAGE (V)
150
100
50
0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G16
U W
Oscillator Frequency
vs Temperature
350
340
Maximum G1 Duty Cycle
vs Ambient Temperature
92
90
88
86
84
82
7700pF
80
THERMAL SHUTDOWN OCCURS
BEYOND THESE POINTS
5500pF
PV
CC
= 12V
f
OSC
= 300kHz
G1, G2
CAPACITANCE
= 1000pF
2200pF
3300pF
250
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G11
78
–55 –35 –15 5 25 45 65 85 105 125
AMBIENT TEMPERATURE (°C)
1530 G12
PV
CC
Supply Current
vs Gate Capacitance
PV
CC
= 12V
T
A
= 25°C
60 GATE CAPACITANCE = C = C
G1
G2
50
40
30
20
10
0
0
PV
CC
Shutdown Supply Current
vs Temperature
80
75
70
65
60
55
50
45
40
35
PV
CC
= 12V
1
2
6
GATE CAPACITANCE (nF)
3
4
5
7
8
30
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1530 G15
1530 G14
Output Overcurrent Protection
Transient Response
2.0
1.5
1.0
0.5
0
0
PV
CC
= 12V
T
A
= 25°C
REFER TO
FIGURE 2
50mV/DIV
2A/DIV
SHORT-CIRCUIT
CURRENT
50µs/DIV
1530 G18
1
2
3 4 5 6 7 8
OUTPUT CURRENT (A)
9
10
1530 G17
5
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