LTM8058 [Linear]
3.1VIN to 31VIN, 2kVAC Isolated DC/DC μModule Converter;
| 型号： | LTM8058 |
| 厂家： | 
Linear |
| 描述： | 3.1VIN to 31VIN, 2kVAC Isolated DC/DC μModule Converter |
| 文件： | 总20页 (文件大小：383K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTM8046
3.1V to 31V , 2kVAC
IN
IN
Isolated DC/DC µModule
Converter
FeaTures
DescripTion
The LTM®8046 is an isolated flyback DC/DC µModule®
(micromodule) converter. The LTM8046 has an isolation
rating of 2kVAC. Included in the package are the switching
controller, power switches, transformer, and all support
components.Operatingoveraninputvoltagerangeof3.1V
to 31V, the LTM8046 supports an output voltage range
of 1.8V to 12V, set by one resistor. Only output, input,
and bias capacitors are needed to finish the design. An
optional capacitor can be used to set the soft-start period.
n
2kVAC Isolated µModule Converter (Tested to 3kVDC)
n
®
UL 60950 Recognized
, File E464570
n
n
n
n
n
n
n
n
Wide Input Voltage Range: 3.1V to 31V
5V at 550mA from 24V
IN
1.8V to 12V Output Voltage
Current Mode Control
Programmable Soft-Start
User Configurable Undervoltage Lockout
SnPb or RoHS Compliant Finish
9mm × 15mm × 4.92mm BGA Package
The LTM8046 is packaged in a 9mm × 15mm × 4.92mm
over-molded ball grid array (BGA) package suitable for
automated assembly by standard surface mount equip-
ment. TheLTM8046isavailablewithSnPb(BGA)orRoHS
compliant terminal finish.
applicaTions
n
Industrial Sensors
n
Industrial Switches
L, LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
n
Ground Loop Mitigation
Typical applicaTion
Maximum Output Current vs VIN
2kV Isolated Low Noise µModule Regulator
700
LTM8046
600
500
400
300
200
100
V
V
IN
OUT
V
V
IN
OUT
4.3V TO 26V
5V
1µF
RUN
BIAS
1µF
100µF
8.45k
FB
SS
–
GND
V
OUT
8046 TA01a
2kVAC ISOLATION
0
5
10
15
(V)
20
25
30
V
IN
8046 TA01b
8046fb
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For more information www.linear.com/LTM8046
LTM8046
absoluTe MaxiMuM raTings
pin conFiguraTion
(Note 1)
TOP VIEW
V , RUN ...................................................................32V
IN
FB, SS.........................................................................5V
A
BANK 4
–
V
Relative to V
..............................................16V
V
OUT
OUT
V + 2V
IN
OUT
B
(Note 5).................................................36V
OUT
C
BIAS................................................................ V + 0.1V
IN
BANK 3
OUT
D
E
F
–
V
–
GND to V
Isolation (Note 2) ...........................2kVAC
OUT
Maximum Internal Temperature (Note 3) .............. 125°C
Peak Solder Reflow Body Temperature ................. 245°C
G
H
J
BANK 2
GND
BANK 1
K
L
V
IN
RUN BIAS SS FB
1
2
3
4
5
6
7
BGA PACKAGE
51-LEAD (15mm × 9mm × 4.92mm)
= 125°C, θ = 21.9°C/W, θ = 7.9°C/W, θ = 17.9°C/W, θ = 8.4°C/W
T
JMAX
JA
JCbottom
JCtop
JB
WEIGHT = 1.5g, θ VALUES DETERMINED PER JEDEC 51-9, 51-12
orDer inForMaTion
PART NUMBER
PAD OR BALL FINISH
PART MARKING*
PACKAGE
TYPE
MSL
RATING
TEMPERATURE RANGE
(See Note 3)
DEVICE
FINISH CODE
LTM8046EY#PBF
LTM8046IY#PBF
LTM8046IY
SAC305 (RoHS)
SAC305 (RoHS)
SnPb (63/37)
LTM8046Y
LTM8046Y
LTM8046Y
LTM8046Y
LTM8046Y
e1
e1
e0
e1
e0
BGA
BGA
BGA
BGA
BGA
3
3
3
3
3
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
LTM8046MPY#PBF
LTM8046MPY
SAC305 (RoHS)
SnPb (63/37)
Consult Marketing for parts specified with wider operating temperature
ranges. *Device temperature grade is indicated by a label on the shipping
container. Pad or ball finish code is per IPC/JEDEC J-STD-609.
• Recommended LGA and BGA PCB Assembly and Manufacturing
Procedures:
www.linear.com/umodule/pcbassembly
• LGA and BGA Package and Tray Drawings:
www.linear.com/packaging
• Pb-free and Non-Pb-free Part Markings:
www.linear.com/leadfree
8046fb
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For more information www.linear.com/LTM8046
LTM8046
elecTrical characTerisTics The l denotes the specifications which apply over the full internal
operating temperature range, otherwise specifications are at TA = 25°C, RUN = 12V (Note 3).
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
l
l
Minimum Input DC Voltage
BIAS = V , VRUN = 2V
3.1
4.3
V
V
IN
BIAS Open, VRUN = 2V
V
DC Voltage
R
R
R
= 14.7k
= 8.45k
= 3.83k
2.5
5
V
V
V
OUT
FB
FB
FB
l
4.75
5.25
1
12
V
V
V
V
Quiescent Current
V
= 0V
µA
%
IN
RUN
Line Regulation
Load Regulation
Ripple (RMS)
6V ≤ V ≤ 31V, I = 0.15A, VRUN = 2V
OUT
1
OUT
OUT
OUT
IN
0.05A ≤ I
≤ 0.4A, VRUN = 2V
1.5
20
%
OUT
I
= 0.1A, BW = 1MHz
mV
VDC
mA
V
OUT
Isolation Test Voltage
Input Short Circuit Current
RUN Pin Input Threshold
RUN Pin Current
(Note 2)
Shorted
3000
1.18
V
30
OUT
VRUN Pin Rising
1.24
1.30
3.1
V
RUN
V
RUN
= 1V
= 1.3V
2.5
0.1
µA
µA
SS Threshold
0.7
–8
10
V
µA
mA
V
SS Sourcing Current
BIAS Current
SS = 0V
V
= 12V, BIAS = 5V, I
= 100mA
OUT
IN
Minimum BIAS Voltage (Note 4)
I
= 100mA
OUT
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 4: This is the BIAS pin voltage at which the internal circuitry is
powered through the BIAS pin and not the integrated regulator. See BIAS
Pin Considerations for details.
Note 5: V + 2V
GND) added to twice the voltage between (V
is defined as the sum of the voltage between (V
–
IN
OUT
IN
–
Note 2: The LTM8046 isolation is tested at 3kVDC for one second.
– V
).
OUT
OUT
Note 3: The LTM8046E is guaranteed to meet performance specifications
from 0°C to 125°C. Specifications over the –40°C to 125°C internal
temperature range are assured by design, characterization and correlation
with statistical process controls. LTM8046I is guaranteed to meet
specifications over the full –40°C to 125°C internal operating temperature
range. The LTM8046MP is guaranteed to meet specifications over the
full –55°C to 125°C internal operating temperature range. Note that
the maximum internal temperature is determined by specific operating
conditions in conjunction with board layout, the rated package thermal
resistance and other environmental factors.
8046fb
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For more information www.linear.com/LTM8046
LTM8046
Typical perForMance characTerisTics
1.8VOUT Efficiency vs Output
Current
2.5VOUT Efficiency vs Output
Current
3.3VOUT Efficiency vs Output
Current
75
70
65
60
55
50
45
75
70
65
60
55
50
75
70
65
60
55
50
BIAS = 3.3V
BIAS = 3.3V
5V
IN
5V
IN
5V
IN
12V
IN
12V
IN
12V
IN
24V
IN
24V
24V
IN
IN
BIAS = 3.3V
0
200
400
600
800
0
100 200 300 400 500 600 700
0
100 200 300 400 500 600 700
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
8046 G01
8046 G02
8046 G03
5VOUT Efficiency vs Output
Current
8VOUT Efficiency vs Output
Current
12VOUT Efficiency vs Output
Current
80
75
70
65
60
55
50
80
80
75
70
65
60
55
50
BIAS = 3.3V
BIAS = 3.3V
BIAS = 3.3V
12V
IN
12V
IN
75
70
65
60
55
50
45
40
5V
5V
IN
IN
20V
24V
IN
IN
5V
IN
12V
IN
0
200
400
600
0
50
100
150
200
250
0
100
200
300
400
500
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
8046 G04
8046 G06
8046 G05
1.8VOUT Input Current vs Output
Current
2.5VOUT Input Current vs Output
Current
3.3VOUT Input Current vs Output
Current
250
250
200
150
100
50
300
250
200
150
100
50
BIAS = 3.3V
BIAS = 3.3V
BIAS = 3.3V
5V
IN
200
150
100
50
5V
IN
5V
IN
12V
12V
IN
IN
12V
IN
24V
IN
24V
IN
24V
IN
0
0
0
0
200
400
600
800
0
200
400
600
800
0
200
400
600
400
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
8046 G07
8046 G08
8046 G09
8046fb
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For more information www.linear.com/LTM8046
LTM8046
Typical perForMance characTerisTics
5VOUT Input Current vs Output
Current
8VOUT Input Current vs Output
Current
12VOUT Input Current vs Output
Current
350
300
250
200
150
100
50
400
350
300
250
200
150
100
50
400
350
300
250
200
150
100
50
BIAS = 3.3V
BIAS = 3.3V
BIAS = 3.3V
5V
IN
5V
IN
5V
IN
12V
IN
12V
IN
12V
IN
20V
IN
24V
IN
0
0
0
0
200
400
800
0
100
200
300
400
500
0
50
100
150
200
250
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
8046 G10
8046 G11
8046 12
1.8VOUT Bias Current vs Output
Current
2.5VOUT Bias Current vs Output
Current
3.3VOUT Bias Current vs Output
Current
14
12
10
8
11
10
9
13
12
11
10
9
BIAS = 3.3V
BIAS = 3.3V
BIAS = 3.3V
5V
IN
5V
IN
5V
IN
12V
IN
12V
12V
IN
IN
8
24V
24V
IN
IN
24V
IN
8
6
7
7
4
6
6
2
5
5
0
4
4
0
200
400
600
800
0
200
400
600
800
0
100 200 300 400 500 600 700
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
8046 G14
8046 G13
8046 G15
5VOUT Bias Current vs Output
Current
8VOUT Bias Current vs Output
Current
12VOUT Bias Current vs Output
Current
14
12
10
8
16
15
14
13
12
11
10
9
16
15
14
13
12
11
10
9
BIAS = 3.3V
BIAS = 3.3V
BIAS = 3.3V
5V
IN
5V
IN
5V
IN
12V
IN
24V
IN
12V
12V
IN
IN
20V
IN
6
4
8
8
2
7
7
0
6
6
0
200
400
600
0
100
200
300
400
500
0
50
100
150
200
250
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
8046 G16
8046 G17
8046 G18
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For more information www.linear.com/LTM8046
LTM8046
Typical perForMance characTerisTics
Maximum Output Current vs VIN
Maximum Output Current vs VIN
Minimum Load vs VIN
800
700
600
500
400
300
200
600
500
400
300
200
100
0
35
30
25
20
15
10
5
BIAS = 3.3V
BIAS = 3.3V
BIAS = 3.3V
1.8V
2.5V
3.3V
5V
OUT
OUT
OUT
OUT
OUT
OUT
1.8V
2.5V
3.3V
OUT
OUT
OUT
8V
12V
0
0
10
20
30
0
3
6
9
12 15 18 21 24 27
(V)
0
8
16
(V)
24
32
V
(V)
V
V
IN
IN
IN
8046 G19
8046 G20
8046 G21
Input Current vs VIN Output
Shorted
Minimum Load vs VIN
12VOUT Minimum Load vs VIN
120
100
80
7
6
5
4
3
2
1
0
25
20
15
10
5
BIAS = 3.3V
BIAS = 3.3V
BIAS = 3.3V
5V
OUT
60
40
8V
20
OUT
20
0
0
0
10
20
(V)
30
40
0
10
30
0
4
8
12
V
IN
V
(V)
V
(V)
IN
IN
8046 G24
8046 G22
8046 G23
Temperature Rise vs Output
Current 2.5VOUT
Temperature Rise vs Output
Current 3.3VOUT
20
15
10
5
20
15
10
5
3.3V
IN
IN
IN
5V
5V
12V
24V
IN
IN
0
0
0
200
400
600
800
0
200
400
600
800
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
8046 G25
8046 G26
8046fb
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For more information www.linear.com/LTM8046
LTM8046
Typical perForMance characTerisTics
Temperature Rise vs Output
Current 8VOUT
Temperature Rise vs Output
Current 12VOUT
Temperature Rise vs Output
Current 5VOUT
20
15
10
5
20
15
10
5
15
10
5
3.3V
IN
IN
5V
3.3V
3.3V
IN
IN
12V
24V
5V
5V
IN
IN
IN
IN
12V
12V
IN
IN
0
0
0
0
100
200
300
0
100 200 300 400 500 600 700
0
100
200
300
400
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
8046 G29
8046 G27
8046 G28
Output Ripple
Step Input Start-Up Waveform
NO C
SS
50mV/
DIV
1V/
DIV
C
= 0.1µF
SS
C
= 0.033µF
SS
8046 G30
8046 G31
2µs/DIV
200µs/DIV
20Ω RESISTIVE LOAD
24V , 5V
24V , 5V
IN OUT
IN
OUT
570mA LOAD
DC1559A DEMO BOARD
UNMODIFIED
150MHz BW
8046fb
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For more information www.linear.com/LTM8046
LTM8046
pin FuncTions
V
(Bank 1): V supplies current to the LTM8046’s
power to the secondary. Above 1.24V, power will be de-
livered to the secondary and 8µA will be fed into the SS
pin. When RUN is less than 1.24V, the pin draws 2.5µA,
allowing for a programmable hysteresis. Do not allow a
negative voltage (relative to GND) on this pin.
IN
IN
internal regulator and to the integrated power switch.
These pins must be locally bypassed with an external,
low ESR capacitor.
GND (Bank 2): This is the primary side local ground of
the LTM8046 primary. In most applications, the bulk of
BIAS (Pin L4): This pin supplies the power necessary to
operate the LTM8046. It must be locally bypassed with
a low ESR capacitor of at least 1μF. Do not allow this pin
the heat flow out of the LTM8046 is through the GND and
–
V
OUT
pads,sotheprintedcircuitdesignhasalargeimpact
onthethermalperformanceofthepart.SeethePCBLayout
and Thermal Considerations sections for more details.
voltage to rise above V .
IN
SS(PinL5):Placeasoft-startcapacitorheretolimitinrush
current and the output voltage ramp rate. Do not allow a
negative voltage (relative to GND) on this pin.
–
–
V
(Bank 3): V
is the return for V . V
and
OUT
V
OUT
OUT OUT
–
comprise the isolated output of the LTM8046. In
OUT
most applications, the bulk of the heat flow out of the
LTM8046 is through the GND and V
FB (Pin L6): Apply a resistor from this pin to GND to set
the output voltage, using the recommended value given
–
pads, so the
OUT
printed circuit design has a large impact on the thermal
performance of the part. See the PCB Layout and Thermal
in Table 1. If Table 1 does not list the desired V
the equation
value,
OUT
Considerationssectionsformoredetails.Applyanexternal
–
–0.84
capacitor between V
and V
.
OUT
OUT
–
R = 31.6 V
kΩ
FB
OUT
V
OUT
(Bank 4): V
and V
comprise the isolated
OUT
OUT
may be used to approximate the value. To the seasoned
designer, this exponential equation may seem unusual.
The equation is exponential due to non-linear current
sources that are used to temperature compensate the
output regulation.
output of the LTM8046 flyback stage. Apply an external
–
–
capacitor between V
and V
. Do not allow V
to
OUT
OUT
OUT
exceed V
.
OUT
RUN (Pin L3): A resistive divider connected to V and this
IN
pinprogramstheminimumvoltageatwhichtheLTM8046
will operate. Below 1.24V, the LTM8046 does not deliver
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For more information www.linear.com/LTM8046
LTM8046
block DiagraM
V
OUT
V
IN
•
0.1µF
•
1µF
RUN
BIAS*
SS
–
V
OUT
CURRENT
MODE
CONTROLLER
FB
GND
8046 BD
*DO NOT ALLOW BIAS VOLTAGE TO EXCEED V
IN
operaTion
The LTM8046 is a stand-alone isolated flyback switching
DC/DC µModule converter that can deliver over 700mA of
output current. This module provides a regulated output
voltage programmable via one external resistor from 1.8V
to 12V. The input voltage range of the LTM8046 is 3.1V
to 31V. Given that the LTM8046 is a flyback converter,
the output current depends upon the input and output
voltages, so make sure that the input voltage is high
enough to support the desired output voltage and load
current. The Typical Performance Characteristics section
that the 2kVAC isolation is verified by a 3kVDC test. This
is because the 2kVAC waveform has a peak voltage 1.414
times higher than 2kV, or 2.83kVDC. For the LTM8046, at
least 3kVDC is applied. For further details please refer to
the Isolation and Working Voltage section.
An internal regulator provides power to the control cir-
cuitry. The bias regulator normally draws power from the
V
pin, but if the BIAS pin is connected to an external
IN
voltage higher than 3.1V, bias power will be drawn from
the external source, improving efficiency. V
must not
BIAS
gives several graphs of the maximum load versus V for
several output voltages.
IN
exceed V . The RUN pin is used to turn on or off the
IN
LTM8046, disconnecting the output and reducing the
Asimplifiedblockdiagramisgiven.TheLTM8046contains
acurrentmodecontroller,powerswitchingelement,power
transformer, power Schottky diode, a modest amount of
input and output capacitance.
input current to 1μA or less.
The LTM8046 is a variable frequency device. For a fixed
input and output voltage, the frequency decreases as
the load increases. For light loads, the current through
the internal transformer may be discontinuous, so that
frequency may appear to decrease. Note that a minimum
load is required to keep the output voltage in regulation.
Refer to the Typical Performance Characteristics section.
The LTM8046 has a galvanic primary to secondary isola-
tion rating of 2kVAC. This is verified by applying 3kVDC
between the primary to secondary for 1 second. Note
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For more information www.linear.com/LTM8046
LTM8046
applicaTions inForMaTion
For most applications, the design process is straight-
in undesirable operation. Using larger values is generally
acceptable, and can yield improved dynamic response, if
it is necessary. Again, it is incumbent upon the user to
verify proper operation over the intended system’s line,
load and environmental conditions.
forward, summarized as follows:
1. Look at Table 1 and find the row that has the desired
input range and output voltage.
2. Apply the recommended C , C
and R .
FB
IN OUT
Ceramic capacitors are small, robust and have very low
ESR. However, not all ceramic capacitors are suitable.
X5R and X7R types are stable over temperature and ap-
plied voltage and give dependable service. Other types,
including Y5V and Z5U have very large temperature and
voltage coefficients of capacitance. In an application cir-
cuit they may have only a small fraction of their nominal
capacitanceresultinginmuchhigheroutputvoltageripple
than expected.
3. Connect BIAS as indicated, or tie to an external source
up to 15V or V , whichever is less.
IN
Whilethesecomponentcombinationshavebeentestedfor
proper operation, it is incumbent upon the user to verify
proper operation overtheintended system’s line, load and
environmentalconditions. Bearinmindthatthemaximum
output current may be limited by junction temperature,
the relationship between the input and output voltage
magnitude and polarity and other factors. Please refer
to the graphs in the Typical Performance Characteristics
section for guidance.
A final precaution regarding ceramic capacitors concerns
the maximum input voltage rating of the LTM8046. A
ceramic input capacitor combined with trace or cable
inductance forms a high-Q (underdamped) tank circuit. If
theLTM8046circuitispluggedintoalivesupply, theinput
voltage can ring to much higher than its nominal value,
possibly exceeding the device’s rating. This situation is
easily avoided; see the Hot-Plugging Safely section.
Capacitor Selection Considerations
The C and C
capacitor values in Table 1 are the
IN
OUT
minimum recommended values for the associated oper-
ating conditions. Applying capacitor values below those
indicated in Table 1 is not recommended, and may result
Table 1. Recommended Components and Configuration (TA = 25°C)
V
V
C
IN
C
R
FB
IN
OUT
OUT
3.2V to 32V
3.2V to 31V
1.8V
2.5V
3.3V
5V
1µF, 50V, 0805 X5R
1µF, 50V, 0805 X5R
1µF, 50V, 0805 X5R
1µF, 25V, 0603 X5R
1µF, 25V, 0603 X5R
1µF, 25V, 0603 X5R
1µF, 25V, 0603 X5R
1µF, 25V, 0603 X5R
18.7k
14.7k
11.8k
8.45k
5.49k
3.83k
14.7k
11.8k
2 × 100µF, 6.3V, 1206 X5R
2 × 100µF, 6.3V, 1206 X5R
100µF, 6.3V, 1206 X5R
100µF, 6.3V, 1206 X5R
47µF, 10V, 1206 X5R
3.2V to 29V
3.2V to 26V
3.2V to 20V
8V
3.2V to 12V
12V
2.5V
3.3V
2 × 10µF, 16V, 1210 X5R
2 × 100µF, 6.3V, 1206 X5R
100µF, 6.3V, 1206 X5R
3.2V to 25V
3.2V to 25V
CBIAS = 1µF 10V 0402 X5R
BIAS = 3.3V for V ≥ 3.3V, V for V < 3.3V. If BIAS = V , the minimum input voltage is 4.3V.
IN
IN
IN
IN
8046fb
10
For more information www.linear.com/LTM8046
LTM8046
applicaTions inForMaTion
BIAS Pin Considerations
The isolation rating of the LTM8046 is not the same as
the working or operational voltage that the application
will experience. This is subject to the application’s power
source, operating conditions, the industry where the end
product is used and other factors that dictate design
requirements such as the gap between copper planes,
traces and component pins on the printed circuit board,
as well as the type of connector that may be used. To
maximizetheallowableworkingvoltage,theLTM8046has
three rows of solder balls removed to facilitate the printed
circuit board design. The ball to ball pitch is 1.27mm,
and the typical ball diameter is 0.78mm. Accounting for
the missing row and the ball diameter, the printed circuit
board may be designed for a metal-to-metal separation
of up to 4.3mm. This may have to be reduced somewhat
to allow for tolerances in solder mask or other printed
circuit board design rules.
The BIAS pin is the output of an internal linear regulator
that powers the LTM8046’s internal circuitry. It is set to
3V and must be decoupled with a low ESR capacitor of at
least 1μF. The LTM8046 will run properly without apply-
ing a voltage to this pin, but will operate more efficiently
and dissipate less power if a voltage greater than 3.1V is
applied. At low V , the LTM8046 will be able to deliver
IN
more output current if BIAS is 3.1V or greater. Up to 31V
may be applied to this pin, but a high BIAS voltage will
causeexcessivepowerdissipationintheinternalcircuitry.
For applications with an input voltage less than 15V, the
BIAS pin is typically connected directly to the V pin. For
IN
input voltages greater than 15V, it is preferred to leave the
BIAS pin separate from the V pin, either powered from
IN
a separate voltage source or left running from the internal
regulator. This has the added advantage of keeping the
physical size of the BIAS capacitor small. Do not allow
To reiterate, the manufacturer’s isolation voltage rating
and the required operational voltage are often different
numbers.InthecaseoftheLTM8046,theisolationvoltage
rating is established by 100% hi-pot testing. The working
or operational voltage is a function of the end product
and its system level specifications. The actual required
operationalvoltageisoftensmallerthanthemanufacturer’s
isolation rating.
BIAS to rise above V .
IN
Soft-Start
For many applications, it is necessary to minimize the
inrush current at start-up. The built-in soft-start circuit
significantly reduces the start-up current spike and out-
put voltage overshoot by applying a capacitor from SS to
GND. When the LTM8046 is enabled, whether from V
For those situations where information about the spacing
of LTM8046 internal circuitry is required, the minimum
metal to metal separation of the primary and secondary is
1.9mm.TheLTM8046isaULrecognizedcomponentunder
UL60950-1,filenumberE464570.TheUL60950-1insula-
tion category of the LTM8046 transformer is Functional.
Considering UL 60950-1 Table 2N and the gap distances
stated above, 4.3mm external and 1.9mm internal, the
LTM8046 may be operated with up to 400V working
voltage in a pollution degree 2 environment. The actual
workingvoltage,insulationcategory,pollutiondegreeand
other critical parameters for the specific end application
depend upon the actual environmental, application and
safety compliance requirements. It is therefore up to the
user to perform a safety and compliance review to ensure
that the LTM8046 is suitable for the intended application.
IN
reaching a sufficiently high voltage or RUN being pulled
high, the LTM8046 will source approximately 8µA out of
the SS pin. As this current gradually charges the capaci-
tor from SS to GND, the LTM8046 will correspondingly
increase the power delivered to the output, allowing for a
graceful turn-on ramp.
Isolation Working Voltage and Safety
The LTM8046 isolation is 100% hi-pot tested by tying
all of the primary pins together, all of the secondary pins
together and subjecting the two resultant circuits to a
differential of 3kVDC for one second. This establishes
the isolation voltage rating of the LTM8046 component.
8046fb
11
For more information www.linear.com/LTM8046
LTM8046
applicaTions inForMaTion
–
V
to V
Reverse Voltage
–
OUT
OUT
V
GND
OUT
The LTM8046 cannot tolerate a reverse voltage from V
OUT
FB
–
–
to V
during operation. If V
raises above V dur-
OUT
OUT
OUT
SS
ing operation, the LTM8046 may be damaged. To protect
against this condition, a low forward drop power Schottky
BIAS
RUN
diode has been integrated into the LTM8046, anti-parallel
–
to V /V
. This can protect the output against many
OUT OUT
reverse voltage faults. Reverse voltage faults can be both
steady state and transient. An example of a steady state
voltage reversal is accidentally misconnecting a powered
LTM8046 to a negative voltage source. An example of
transient voltage reversals is a momentary connection to
V
V
IN
OUT
GND
THERMAL/INTERCONNECT VIAS
a negative voltage. It is also possible to achieve a V
OUT
8046 F01
reversal if the load is short-circuited through a long cable.
The inductance of the long cable forms an LC tank circuit
Figure 1. Layout Showing Suggested External Components,
Planes and Thermal Vias
with the V
capacitance, which drives V
negative.
OUT
OUT
Avoid these conditions.
Figure 1 for a suggested layout. Ensure that the grounding
and heat sinking are acceptable.
Minimum Load
The LTM8046 requires a minimum load in order to main-
tain regulation. If less than the minimum load is applied,
the output voltage may rise beyond the intended value
uncontrollably, possibly damaging the LTM8046 or the
application system. Avoid this situation. The Typical
Performance Characteristics section provides graphs of
the minimum required load for several input and output
conditions at room temperature.
A few rules to keep in mind are:
1. Place the R
resistor as close as possible to its re-
ADJ
spective pin.
2. Place the C capacitor as close as possible to the V
IN
IN
and GND connections of the LTM8046.
3. Place the C
capacitor as close as possible to V
OUT
OUT
–
and V
.
OUT
The LTM8046 is designed to skip switching cycles, if
necessary, to maintain regulation. While cycle skipping,
the output ripple may be higher than when the LTM8046
is not skipping cycles. The user must validate the perfor-
mance of the LTM8046 application over the appropriate
temperature, line, load and other operating conditions.
4. Place the C and C
capacitors such that their
OUT
IN
ground current flow directly adjacent or underneath
the LTM8046.
5. Connect all of the GND connections to as large a copper
pour or plane area as possible on the top layer. Avoid
breaking the ground connection between the external
components and the LTM8046.
PCB Layout
Most of the headaches associated with PCB layout have
been alleviated or even eliminated by the high level of
integration of the LTM8046. The LTM8046 is neverthe-
less a switching power supply, and care must be taken to
minimizeelectricalnoisetoensureproperoperation. Even
with the high level of integration, you may fail to achieve
specified operation with a haphazard or poor layout. See
6. Use vias to connect the GND copper area to the board’s
internal ground planes. Liberally distribute these GND
vias to provide both a good ground connection and
thermal path to the internal planes of the printed circuit
board. Pay attention to the location and density of the
thermal vias in Figure 1. The LTM8046 can benefit from
theheatsinkingaffordedbyviasthatconnecttointernal
8046fb
12
For more information www.linear.com/LTM8046
LTM8046
applicaTions inForMaTion
GND planes at these locations, due to their proximity
to internal power handling components. The optimum
number of thermal vias depends upon the printed
circuit board design. For example, a board might use
very small via holes. It should employ more thermal
vias than a board that uses larger holes.
voltage, output power and ambient temperature. The
temperature rise curves given in the Typical Performance
Characteristicssectioncanbeusedasaguide.Thesecurves
2
were generated by the LTM8046 mounted to a 58cm
4-layer FR4 printed circuit board. Boards of other sizes
and layer count can exhibit different thermal behavior, so
it is incumbent upon the user to verify proper operation
over the intended system’s line, load and environmental
operating conditions.
The printed circuit board construction has an impact on
theisolationperformanceoftheendproduct.Forexample,
increased trace and layer spacing, as well as the choice
of core and prepreg materials (such as using polyimide
versusFR4)cansignificantlyaffecttheisolationwithstand
of the end product.
Forincreasedaccuracyandfidelitytotheactualapplication,
many designers use FEA to predict thermal performance.
To that end, the Pin Configuration section of the data sheet
typically gives four thermal coefficients:
Hot-Plugging Safely
ꢀ θ : Thermal resistance from junction to ambient
JA
The small size, robustness and low impedance of ceramic
capacitors make them an attractive option for the input
bypass capacitor of the LTM8046. However, these capaci-
tors can cause problems if the LTM8046 is plugged into a
live supply (see Linear Technology Application Note 88 for
a complete discussion). The low loss ceramic capacitor
combined with stray inductance in series with the power
source forms an underdamped tank circuit, and the volt-
ꢀ θ
: Thermal resistance from junction to the bot-
JCbottom
tom of the product case
ꢀ θ : Thermal resistance from junction to top of the
JCtop
product case
ꢀ θ : Thermal resistance from junction to the printed
JB
circuit board.
While the meaning of each of these coefficients may seem
to be intuitive, JEDEC has defined each to avoid confusion
and inconsistency. These definitions are given in JESD
51-12, and are quoted or paraphrased as follows:
age at the V pin of the LTM8046 can ring to more than
IN
twice the nominal input voltage, possibly exceeding the
LTM8046’s rating and damaging the part. If the input
supply is poorly controlled or the user will be plugging
the LTM8046 into an energized supply, the input network
should be designed to prevent this overshoot. This can
be accomplished by installing a small resistor in series
θ
JA
is the natural convection junction-to-ambient air
thermal resistance measured in a one cubic foot sealed
enclosure. This environment is sometimes referred to
as still air although natural convection causes the air to
move. This value is determined with the part mounted to a
JESD 51-9 defined test board, which does not reflect an
actual application or viable operating condition.
to V , but the most popular method of controlling input
IN
voltage overshoot is adding an electrolytic bulk capacitor
to V . This capacitor’s relatively high equivalent series
IN
resistance damps the circuit and eliminates the voltage
overshoot. The extra capacitor improves low frequency
ripplefilteringandcanslightlyimprovetheefficiencyofthe
circuit, though it can be a large component in the circuit.
θ
is the junction-to-board thermal resistance with
JCbottom
allofthecomponentpowerdissipationflowingthroughthe
bottom of the package. In the typical µModule converter,
the bulk of the heat flows out the bottom of the package,
but there is always heat flow out into the ambient envi-
ronment. As a result, this thermal resistance value may
be useful for comparing packages but the test conditions
don’t generally match the user’s application.
Thermal Considerations
The LTM8046 output current may need to be derated if it
is required to operate in a high ambient temperature. The
amount of current derating is dependent upon the input
8046fb
13
For more information www.linear.com/LTM8046
LTM8046
applicaTions inForMaTion
be inappropriate to attempt to use any one coefficient to
correlate to the junction temperature vs load graphs given
in the product’s data sheet. The only appropriate way to
use the coefficients is when running a detailed thermal
analysis, such as FEA, which considers all of the thermal
resistances simultaneously.
θ
isdeterminedwithnearlyallofthecomponentpower
JCtop
dissipation flowing through the top of the package. As the
electricalconnectionsofthetypicalµModuleconverterare
on the bottom of the package, it is rare for an application
to operate such that most of the heat flows from the junc-
tion to the top of the part. As in the case of θ
, this
JCbottom
value may be useful for comparing packages but the test
conditions don’t generally match the user’s application.
A graphical representation of these thermal resistances
is given in Figure 2.
θ
is the junction-to-board thermal resistance where
JB
The blue resistances are contained within the µModule
converter, and the green are outside.
almost all of the heat flows through the bottom of the
µModule converter and into the board, and is really the
sum of the θ
bottom of the part through the solder joints and through a
portion of the board. The board temperature is measured
a specified distance from the package, using a two-sided,
two-layer board. This board is described in JESD 51-9.
The die temperature of the LTM8046 must be lower than
the maximum rating of 125°C, so care should be taken in
the layout of the circuit to ensure good heat sinking of the
LTM8046. The bulk of the heat flow out of the LTM8046
is through the bottom of the module and the BGA pads
into the printed circuit board. Consequently a poor printed
circuit board design can cause excessive heating, result-
ing in impaired performance or reliability. Please refer to
the PCB Layout section for printed circuit board design
suggestions.
and the thermal resistance of the
JCbottom
Giventhesedefinitions,itshouldnowbeapparentthatnone
of these thermal coefficients reflects an actual physical
operating condition of a µModule converter. Thus, none
of them can be individually used to accurately predict the
thermal performance of the product. Likewise, it would
JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD)
JUNCTION-TO-CASE (TOP)
RESISTANCE
CASE (TOP)-TO-AMBIENT
RESISTANCE
JUNCTION-TO-BOARD RESISTANCE
JUNCTION
AMBIENT
JUNCTION-TO-CASE
(BOTTOM) RESISTANCE
CASE (BOTTOM)-TO-BOARD
BOARD-TO-AMBIENT
RESISTANCE
RESISTANCE
8046 F02
µMODULE DEVICE
Figure 2.
8046fb
14
For more information www.linear.com/LTM8046
LTM8046
Typical applicaTions
3.3V Isolated Flyback Converter
LTM8046
V
V
IN
3.3V TO 29V
OUT
V
V
IN
OUT
3.3V
RUN
1µF
3.3V
BIAS
100µF
1µF
11.8k
FB
SS
–
V
OUT
GND
8046 TA02a
2kVAC ISOLATION
Maximum Output Current vs VIN
800
700
600
500
400
300
200
0
10
20
30
V
(V)
IN
8046 TA02b
8046fb
15
For more information www.linear.com/LTM8046
LTM8046
Typical applicaTions
Use Two LTM8046 Flyback Converters to Generate 5V
LTM8046
V
IN
V
5V
22µF
–5V
V
IN
OUT
4.3V TO 26V
1µF
RUN
BIAS
100µF
1µF
8.45k
FB
SS
1µF
–
GND
V
OUT
2kVAC ISOLATION
LTM8046
V
V
IN
OUT
1µF
RUN
BIAS
100µF
1µF
8.45k
FB
SS
1µF
–
GND
V
OUT
8046 TA03a
2kVAC ISOLATION
Maximum Output Current vs VIN
700
600
500
400
300
200
100
0
5
10
15
(V)
20
25
30
V
IN
8046 TA03b
8046fb
16
For more information www.linear.com/LTM8046
LTM8046
package DescripTion
Pin Assignment Table
(Arranged by Pin Number)
PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME
–
A1
A2
A3
A4
A5
A6
A7
V
V
V
V
V
V
V
B1
B2
B3
B4
B5
B6
B7
V
V
V
V
V
V
V
C1
C2
C3
C4
C5
C6
C7
V
V
V
V
V
V
V
D1
D2
D3
D4
D5
D6
D7
-
-
-
-
-
-
-
E1
E2
E3
E4
E5
E6
E7
-
-
-
-
-
-
-
F1
F2
F3
F4
F5
F6
F7
-
-
-
-
-
-
-
G1 GND
G2 GND
G3 GND
G4 GND
G5 GND
G6 GND
G7 GND
H1
H2
-
-
J1
J2
V
-
K1
K2
V
-
L1
L2
V
-
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
IN
IN
IN
–
–
–
–
–
–
H3 GND
H4 GND
H5 GND
H6 GND
H7 GND
J3 GND
J4 GND
J5 GND
J6 GND
J7 GND
K3 GND
K4 GND
K5 GND
K6 GND
K7 GND
L3 RUN
L4 BIAS
L5 SS
L6 FB
L7 GND
–
–
–
–
–
–
package phoTo
8046fb
17
For more information www.linear.com/LTM8046
LTM8046
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
Z
/ / b b b
Z
3 . 8 1 0
2 . 5 4 0
1 . 2 7 0
0 . 3 1 7 5
0 . 3 1 7 5
1 . 2 7 0
0 . 0 0 0
2 . 5 4 0
3 . 8 1 0
8046fb
18
For more information www.linear.com/LTM8046
LTM8046
revision hisTory
REV
DATE
07/14 Add MP-grade
04/15 changed from 32V to 31V
DESCRIPTION
PAGE NUMBER
A
2, 3
1
B
V
IN
8046fb
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
19
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LTM8046
Typical applicaTion
Maximum Output Current vs VIN
12V Isolated Flyback Converter
300
250
200
150
100
50
LTM8046
V
V
IN
OUT
V
V
OUT
IN
12V
3.3VDC TO 12VDC
1µF
RUN
3.3V
BIAS
10µF
×2
1µF
3.83k
FB
SS
–
GND
V
OUT
8046 TA04
2kVAC ISOLATION
0
3
6
9
12
V
(V)
IN
8046 TA04b
Design resources
SUBJECT
DESCRIPTION
µModule Design and Manufacturing Resources
Design:
Manufacturing:
• Quick Start Guide
• Selector Guides
• Demo Boards and Gerber Files
• Free Simulation Tools
• PCB Design, Assembly and Manufacturing Guidelines
• Package and Board Level Reliability
µModule Regulator Products Search
1. Sort table of products by parameters and download the result as a spread sheet.
2. Search using the Quick Power Search parametric table.
TechClip Videos
Quick videos detailing how to bench test electrical and thermal performance of µModule products.
Digital Power System Management
Linear Technology’s family of digital power supply management ICs are highly integrated solutions that
offer essential functions, including power supply monitoring, supervision, margining and sequencing,
and feature EEPROM for storing user configurations and fault logging.
relaTeD parTs
PART NUMBER DESCRIPTION
COMMENTS
LTM8057
LTM8058
LTM8048
LTM8045
UL60950 Recognized 1.5W, 2kVAC Isolated µModule 3.1V ≤ V ≤ 31V, 2.5V ≤ V
≤ 12V, 5% V
Accuracy, Internal Isolated
IN
OUT
OUT
Converter
Transformer, 9mm × 11.25mm × 4.92mm BGA
≤ 12V, 2.5% V
UL60950 Recognized 1.5W, 2kVAC Isolated µModule 3.1V ≤ V ≤ 31V, 1.2V ≤ V
Accuracy, 1mV Output
P-P
IN
OUT
OUT
Converter with LDO Post Regulator
Ripple, Internal Isolated Transformer, 9mm × 11.25mm × 4.92mm BGA
3.1V ≤ V ≤ 32V, 1.2V ≤ V ≤ 12V, 2.5% V Accuracy, 1mV Output
1.5W, 725VDC Galvanically Isolated µModule
Converter with LDO Post Regulator
IN
OUT
OUT
P-P
Ripple, Internal Isolated Transformer, 9mm × 11.25mm × 4.92mm BGA
Inverting or SEPIC μModule DC/DC Converter with
Up to 700mA Output Current
2.8V ≤ V ≤ 18V, 2.5V ≤ V
≤ 15V, Synchronizable, No Derating or
IN
OUT
Logic Level Shift for Control Inputs When Inverting, 6.25mm × 11.25mm
× 4.92mm BGA
LTM4609
LTM8061
36V , 5A DC/DC μModule Buck-Boost Regulator
4.5V ≤ V ≤ 36V, 0.8V ≤ V
≤ 34V, Adjustable Soft-Start, Clock Input,
IN
IN
OUT
15mm × 15mm × 2.82mm LGA and 15mm × 15mm × 3.42mm BGA
32V, 2A Step-Down μModule Battery Charger with
Programmable Input Current Limit
Suitable for Charging Single and Dual Cell Li-Ion or Li-Poly Batteries, 4.95V ≤ V
≤ 32V, C/10 or Adjustable Timer Charge Termination, NTC Resistor Monitor Input,
9mm × 15mm × 4.32mm LGA
IN
8046fb
LT 0415 REV B • PRINTED IN USA
20 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
(408)432-1900 FAX: (408) 434-0507 www.linear.com/LTM8046
ꢀLINEAR TECHNOLOGY CORPORATION 2014
相关型号：
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