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
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
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
LEAD FREE FINISH
LT3506EDHD#PBF
LT3506AEDHD#PBF
LT3506IDHD#PBF
LT3506AIDHD#PBF
LT3506EFE#PBF
LT3506AEFE#PBF
LT3506IFE#PBF
LT3506AIFE#PBF
TAPE AND REEL
LT3506EDHD#TRPBF
LT3506AEDHD#TRPBF
LT3506IDHD#TRPBF
LT3506AIDHD#TRPBF
LT3506EFE#TRPBF
LT3506AEFE#TRPBF
LT3506IFE#TRPBF
LT3506AIFE#TRPBF
LEAD BASED FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT3506EDHD
LT3506EDHD#TR
3506
16-Lead (5mm x 4mm) Plastic DFN
–40°C to 85°C
LT3506AEDHD
LT3506AEDHD#TR
3506A
16-Lead (5mm x 4mm) Plastic DFN
–40°C to 85°C
LT3506IDHD
LT3506IDHD#TR
3506
16-Lead (5mm x 4mm) Plastic DFN
–40°C to 125°C
LT3506AIDHD
LT3506AIDHD#TR
3506A
16-Lead (5mm x 4mm) Plastic DFN
–40°C to 125°C
LT3506EFE
LT3506EFE#TR
3506EFE
16-Lead Plastic TSSOP Narrow
–40°C to 85°C
LT3506AEFE
LT3506AEFE#TR
3506AEFE
16-Lead Plastic TSSOP Narrow
–40°C to 85°C
LT3506IFE
LT3506IFE#TR
3506IFE
16-Lead Plastic TSSOP Narrow
–40°C to 125°C
LT3506AIFE
LT3506AIFE#TR
3506AIFE
16-Lead Plastic TSSOP Narrow
–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/
3506afb
U
ORDER I FOR ATIO
W
U
U
TOP VIEW
16 FB1
15 V
C1
14 PG1
17
13 RUN/SS1
12 RUN/SS2
11 PG2
10 V
C2
9
FB2
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
PI CO FIGURATIO
U
U
PART MARKING*
3506
3506A
3506
3506A
3506EFE
3506AEFE
3506IFE
3506AIFE
PACKAGE DESCRIPTION
16-Lead (5mm x 4mm) Plastic DFN
16-Lead (5mm x 4mm) Plastic DFN
16-Lead (5mm x 4mm) Plastic DFN
16-Lead (5mm x 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
LT3506/LT3506A
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN(MIN)
I
INQ
I
INSD
V
FB
I
FB
V
FB(REG)
gm
EA
A
V
I
VC
V
VC(THRESH)
V
VC(CLAMP)
f
SW
PARAMETER
Undervoltage Lockout
Quiescent Current
Shutdown Current
Feedback Voltage
Not Switching
V
RUNSS
= 0V
–40°C to 85°C, EDHD
–40°C to 85°C, EFE
–40°C to 125°C, IFE, IDHD
V
FB
= 800mV, V
C
= 0.4V
V
IN
= 5V to 25V
●
●
●
●
The
●
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
●
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
uMhos
µA
µA
V
V
792
784
784
800
800
800
40
0.005
350
400
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.
3506afb
LT3506/LT3506A
TYPICAL PERFOR A CE CHARACTERISTICS
100
Efficiency, V
OUT
= 1.8V (LT3506A)
V
OUT
= 1.8V
L = 4.7µH (COILCRAFT MSS6122-472MLB)
90 T
A
= 25°C
80
EFFICIENCY (%)
70
60
50
40
V
IN
= 4.5V
V
IN
= 12V
V
IN
= 25V
0
0.2
0.4
1.0 1.2
OUTPUT CURRENT (A)
0.6
0.8
1.4
1.6
EFFICIENCY (%)
80
75
70
65
60
55
50
0
0.4
0.8
I
OUT
(A)
1.2
1.6
3506 G02
EFFICIENCY (%)
30
Maximum Load Current,
V
OUT
= 1.8V (LT3506A)
1.8
T
A
= 25°C
L = 2.2µH
LOAD CURRENT (A)
1.8
L = 1.5µH
1.4
L = 1µH
1.2
L = 3.3µH
1.4
L = 2.2µH
SWITCH VOLTAGE (mV)
1.6
LOAD CURRENT (A)
1.0
0
2
4
8
10 12
6
INPUT VOLTAGE (V)*
Boost Pin Current
40
T
A
= 25°C
3.0
2.5
BOOST CURRENT (mA)
30
CURRENT LIMIT (A)
2.0
20
MINIMUM
1.5
1.0
0.5
FREQUENCY (kHz)
10
0
0
1.0
1.5
0.5
SWITCH CURRENT (A)
U W
3506 G01
100
Efficiency, V
OUT
= 3.3V (LT3506)
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
0
0.4
0.8
I
OUT
(A)
1.2
1.6
3506 G03
V
OUT
= 3.3V
95 L = 6.4µH (SUMIDA CR54-6R4)
T
A
= 25°C
90
85
V
IN
= 5V
V
IN
= 8V
V
IN
= 12V
V
IN
= 15V
V
IN
= 25V
V
IN
= 25V
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
L = 4.7µH
400
Switch V
CESAT
T
A
= 25°C
1.6
300
200
1.2
100
14
16
1.0
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
Current Limit vs Duty Cycle
T
A
= 25°C
TYPICAL
650
700
Frequency vs Temperature
1.20
1.15
FREQUENCY (MHz)
LT3506A
600
LT3506
550
1.10
1.05
2.0
3506 G07
0
0
20
60
40
DUTY CYCLE (%)
80
100
3506 G08
500
–50 –25
0
25
50
75
TEMPERATURE (°C)
100
1.00
125
3506 G10
3506afb
LT3506/LT3506A
TYPICAL PERFOR A CE CHARACTERISTICS
I
RUN/SS
vs Temperature
3.0
2.5
RUNN/SS THRESHOLDS (V)
RUN/SS CURRENT (µA)
2.0
1.5
1.0
0.5
0
–50
1.4
1.2
1.0
0.8
0.6
TO RUN
0.4
0.2
–25
0
25
50
75
TEMPERATURE (°C)
100
125
0
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
TO SWITCH
PI FU CTIO S
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 connected 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.
U W
RUN/SS Thresholds vs
Temperature
3506 G12
3506 G13
U
U
U
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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