Maximum Junction Temperature .......................... 125°C
Operating Temperature Range (Note 2)
E Grade ................................................–40°C to 85°C
I Grade ............................................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 125°C
PIN CONFIGURATION
TOP VIEW
BOOST1
SW1
V
IN1
V
IN1
V
IN2
V
IN2
SW2
BOOST2
1
2
3
4
5
6
7
8
17
16 FB1
15 V
C1
14 PG1
13 RUN/SS1
12 RUN/SS2
11 PG2
10 V
C2
9
FB2
BOOST1
SW1
V
IN1
V
IN1
V
IN2
V
IN2
SW2
BOOST2
1
2
3
4
5
6
7
8
17
TOP VIEW
16 FB1
15 V
C1
14 PG1
13 RUN/SS1
12 RUN/SS2
11 PG2
10 V
C2
9
FB2
DHD PACKAGE
16-LEAD PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W,
θ
JC
= 4.3°C/W
EXPOSED PAD (PIN 17) IS GND MUST BE SOLDERED TO PCB
FE PACKAGE
16-LEAD PLASTIC TSSOP NARROW
T
JMAX
= 125°C,
θ
JA
= 45°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 17) IS GND MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LT3506EDHD#PBF
LT3506AEDHD#PBF
LT3506IDHD#PBF
LT3506AIDHD#PBF
LT3506EFE#PBF
LT3506AEFE#PBF
LT3506IFE#PBF
LT3506AIFE#PBF
LEAD BASED FINISH
LT3506EDHD
LT3506AEDHD
LT3506IDHD
LT3506AIDHD
LT3506EFE
LT3506AEFE
LT3506IFE
LT3506AIFE
TAPE AND REEL
LT3506EDHD#TRPBF
LT3506AEDHD#TRPBF
LT3506IDHD#TRPBF
LT3506AIDHD#TRPBF
LT3506EFE#TRPBF
LT3506AEFE#TRPBF
LT3506IFE#TRPBF
LT3506AIFE#TRPBF
TAPE AND REEL
LT3506EDHD#TR
LT3506AEDHD#TR
LT3506IDHD#TR
LT3506AIDHD#TR
LT3506EFE#TR
LT3506AEFE#TR
LT3506IFE#TR
LT3506AIFE#TR
PART MARKING*
3506
3506A
3506
3506A
3506EFE
3506AEFE
3506IFE
3506AIEFE
PART MARKING*
3506
3506A
3506
3506A
3506EFE
3506AEFE
3506IFE
3506AIEFE
PACKAGE DESCRIPTION
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead Plastic TSSOP Narrow
16-Lead Plastic TSSOP Narrow
16-Lead Plastic TSSOP Narrow
16-Lead Plastic TSSOP Narrow
PACKAGE DESCRIPTION
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead Plastic TSSOP Narrow
16-Lead Plastic TSSOP Narrow
16-Lead Plastic TSSOP Narrow
16-Lead Plastic TSSOP Narrow
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 125°C
–40°C to 125°C
–40°C to 85°C
–40°C to 85°C
–40°C to 125°C
–40°C to 125°C
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 125°C
–40°C to 125°C
–40°C to 85°C
–40°C to 85°C
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
3506afc
2
LT3506/LT3506A
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN(MIN)
I
INQ
I
INSD
V
FB
PARAMETER
Undervoltage Lockout
Quiescent Current
Shutdown Current
Feedback Voltage
Not Switching
V
RUNSS
= 0V
–40°C to 85°C, DHD
–40°C to 85°C, EFE
–40°C to 125°C, IFE
V
FB
= 800mV, V
C
= 0.4V
V
IN
= 5V to 25V
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
IN
= 5V, V
BOOST
= 8V, unless otherwise noted. (Note 2)
CONDITIONS
l
MIN
TYP
3.4
3.8
30
MAX
3.6
4.8
45
808
816
816
100
UNITS
V
mA
μA
mV
mV
mV
nA
%/V
μMhos
μA
μA
V
V
792
784
784
800
800
800
40
0.005
350
400
I
FB
V
FB(REG)
gm
EA
A
V
I
VC
V
VC(THRESH)
V
VC(CLAMP)
f
SW
FB Pin Bias Current
Reference Line Regulation
Error Amp GM
Error Amp Voltage Gain
V
C
Source Current
V
C
Sink Current
V
C
Switching Threshold
V
C
Clamp Voltage
Switching Frequency
Switching Phase
V
FB
= 0.6V, V
C
= 0V
V
FB
= 1.2V, V
C
= 1100mV
30
30
0.7
1.9
LT3506
LT3506A
(Note 5)
LT3506
LT3506A
V
FB
= 0V
(Note 3)
I
SW
= 1A
I
SW
= 1A
I
SW
= 1A
500
1
89
78
575
1.1
180
93
88
0.4
170
650
1.2
kHz
MHz
Deg
%
%
V
kHz
DC
V
FB(SWTHRESH)
f
FOLD
I
SW
V
SW(SAT)
I
LSW
V
BOOST(MIN)
I
BOOST
I
RUN/SS
V
RUN/SS(THRESH)
V
FB(PGTHRESH)
V
PG(LOW)
I
LPG
Maximum Duty Cycle
Frequency Shift Threshold on FB
Foldback Frequency
Switch Current Limit
Switch V
CESAT
(Note 4)
Switch Leakage Current
Minimum Boost Voltage Above Switch
BOOST Pin Current
RUN/SS Current
RUN/SS Threshold
V
FB
PG Threshold
PG Voltage Output Low
PG Pin Leakage
2.0
2.6
210
3.6
10
A
mV
μA
V
mA
μA
V
mV
1.5
20
2.1
0.3
0.8
720
0.22
0.1
2.5
30
V
FB
Rising
V
FB
= 640mV, I
PG
= 250μA
V
PG
= 2V
0.4
1
V
μA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LT3506E/LT3506AE are guaranteed to meet performance
specifications from 0°C to 85°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls. The LT3506I/LT3506AI are
guaranteed and tested over the full –40°C to 125°C operating temperature
range.
Note 3:
Current limit is guaranteed by design and/or correlation to static
test. Slope compensation reduces current limit at high duty cycle.
Note 4:
Switch V
CESAT
guaranteed by design.
Note 5:
Switching phase is guaranteed by design.
3506afc
3
LT3506/LT3506A
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency, V
OUT
= 1.8V (LT3506A)
90
V
OUT
= 1.8V
L = 2.2μH (COILCRAFT LPS4012-222)
85
T
A
= 25°C
80
EFFICIENCY (%)
75
70
V
IN
= 10V
65
60
55
50
0
0.2
0.4
0.6
0.8
I
OUT
(A)
3506 G01
Efficiency, V
OUT
= 3.3V (LT3506)
100
V
OUT
= 3.3V
95 L = 6.4μH (SUMIDA CR54-6R4)
T
A
= 25°C
90
85
80
75
70
65
60
55
V
IN
= 25V
V
IN
= 12V
100
Efficiency, V
OUT
= 5V (LT3506)
V
OUT
= 5V
95 L = 10μH (COOPER UP1B-100)
T
A
= 25°C
90
85
80
75
70
65
60
55
50
V
IN
= 25V
V
IN
= 15V
V
IN
= 5V
EFFICIENCY (%)
V
IN
= 8V
V
IN
= 7V
EFFICIENCY (%)
V
IN
= 4.5V
1.0
1.2
1.4
1.6
50
0
0.4
0.8
I
OUT
(A)
1.2
1.6
3506 G02
0
0.4
0.8
I
OUT
(A)
1.2
1.6
3506 G03
Maximum Load Current,
V
OUT
= 1.8V (LT3506A)
1.8
T
A
= 25°C
L = 2.2μH
1.6
LOAD CURRENT (A)
LOAD CURRENT (A)
L = 1.5μH
1.4
L = 1μH
1.2
1.6
1.8
Maximum Load Current,
V
OUT
= 3.3V (LT3506A)
SLOPE COMPENSATION REQUIRES
L > 2.2μH FOR V
IN
< 7 WITH V
OUT
= 3.3V
T
A
= 25°C
SWITCH VOLTAGE (mV)
L = 4.7μH
L = 3.3μH
1.4
400
Switch V
CESAT
T
A
= 25°C
300
200
L = 2.2μH
1.2
100
1.0
1.0
0
2
4
8
10 12
6
INPUT VOLTAGE (V)*
14
16
0
5
15
20
10
INPUT VOLTAGE (V)*
25
3506 G05
0
0
0.5
1.0
SW CURRENT (A)
1.5
2.0
3506 G06
3506 G04
Boost Pin Current
40
T
A
= 25°C
3.0
2.5
BOOST CURRENT (mA)
30
CURRENT LIMIT (A)
2.0
Current Limit vs Duty Cycle
T
A
= 25°C
TYPICAL
MINIMUM
1.5
1.0
0.5
20
10
0
0
1.0
1.5
0.5
SWITCH CURRENT (A)
0
2.0
3506 G07
0
20
60
40
DUTY CYCLE (%)
80
100
3506 G08
3506afc
4
LT3506/LT3506A
TYPICAL PERFORMANCE CHARACTERISTICS
Frequency vs Temperature
700
1.20
3.0
2.5
RUN/SS CURRENT (μA)
650
FREQUENCY (kHz)
LT3506A
600
LT3506
550
1.05
1.10
1.15
FREQUENCY (MHz)
2.0
1.5
1.0
0.5
500
–50 –25
1.00
125
0
–50
I
RUN/SS
vs Temperature
1.4
1.2
RUNN/SS THRESHOLDS (V)
1.0
RUN/SS Thresholds
vs Temperature
TO SWITCH
0.8
0.6
TO RUN
0.4
0.2
0
–50 –25
0
25
50
75
TEMPERATURE (°C)
100
–25
75
0
25
50
TEMPERATURE (°C)
100
125
50
25
75
0
TEMPERATURE (°C)
100
125
3506 G10
3506 G12
3506 G13
PIN FUNCTIONS
BOOST1 (Pin 1), BOOST2 (Pin 8):
The BOOST pins are
used to provide drive voltages, higher than the input
voltage, to the internal bipolar NPN power switches. Tie
through a diode from V
OUT
or from V
IN
.
SW1 (Pin 2), SW2 (Pin 7):
The SW pins are the outputs
of the internal power switches. Connect these pins to the
inductors, catch diodes and boost capacitors.
V
IN1
(Pins 3, 4):
The V
IN1
pins supply current to the LT3506’s
internal regulator and to the internal power switch con-
nected to SW1. These pins must be locally bypassed.
V
IN2
(Pins 5, 6):
The V
IN2
pins supply current to the inter-
nal power switch connected to SW2 and must be locally
bypassed. Connect these pins directly to V
IN1
unless power
for channel 2 is coming from a different source.
RUN/SS1 (Pin 13), RUN/SS2 (Pin 12):
The RUN/SS pins
are used to shut down the individual switching regula-
tors and the internal bias circuits. They also provide a
soft-start function. To shut down either regulator, pull the
RUN/SS pin to ground with an open drain or collector.
Tie a capacitor from these pins to ground to limit switch
current during start-up. If neither feature is used, leave
these pins unconnected.
PG1 (Pin 14), PG2 (Pin 11):
The Power Good pins are
the open collector outputs of an internal comparator. PG
remains low until the FB pin is within 10% of the final
regulation voltage. As well as indicating output regulation,
the PG pins can be used to sequence the two switching
regulators. These pins can be left unconnected. The PG
outputs are valid when V
IN
is greater than 3.4V and either
of the RUN/SS pins is high. The PG comparators are
disabled in shutdown.
V
C1
(Pin 15), V
C2
(Pin 10):
The V
C
pins are the outputs of
the internal error amps. The voltages on these pins control
the peak switch currents. These pins are normally used
to compensate the control loops, but can also be used to
override the loops. Pull these pins to ground with an open
drain to shut down each switching regulator.
FB1 (Pin 16), FB2 (Pin 9):
The LT3506 regulates each
feedback pin to 800mV. Connect the feedback resistor
divider taps to these pins.
Exposed Pad (Pin 17):
The Exposed Pad of the package
provides both electrical contact to ground and good thermal
contact to the printed circuit board. The Exposed Pad must
be soldered to the circuit board for proper operation.
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