LQH4C100K24 [Linear]
1.2MHz/2.2MHz Inverting DC/DC Converters in ThinSOT; 1.2MHz的/采用ThinSOT封装的2.2MHz的输出DC / DC转换器型号: | LQH4C100K24 |
厂家: | Linear |
描述: | 1.2MHz/2.2MHz Inverting DC/DC Converters in ThinSOT |
文件: | 总12页 (文件大小:426K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT1931/LT1931A
1.2MHz/2.2MHz Inverting
DC/DC Converters in ThinSOT
U
FEATURES
DESCRIPTIO
The LT®1931/LT1931A are the industry’s highest power
inverting SOT-23 current mode DC/DC converters. Both
parts include a 1A integrated switch allowing high current
outputs to be generated in a small footprint. The LT1931
switchesat1.2MHzwhiletheLT1931Aswitchesat2.2MHz.
These high speeds enable the use of tiny, low cost
capacitors and inductors 2mm or less in height. The
LT1931 is capable of generating –5V at 350mA or –12V
at 150mA from a 5V supply, while the LT1931A can
generate –5V at 300mA using significantly smaller induc-
tors. Both parts are easy pin-for-pin upgrades for higher
power LT1611 applications.
■
Fixed Frequency 1.2MHz/2.2MHz Operation
■
Very Low Noise: 1mVP-P Output Ripple
■
–5V at 350mA from 5V Input
–12V at 150mA from 5V Input
■
■
Uses Small Surface Mount Components
■
Wide Input Range: 2.6V to 16V
■
Low Shutdown Current: <1µA
■
Low VCESAT Switch: 400mV at 1A
■
Pin-for-Pin Compatible with the LT1611
Low Profile (1mm) ThinSOTTM Package
■
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APPLICATIO S
The LT1931/LT1931A operate in a dual inductor inverting
topology that filters both the input side and output side
current.Verylowoutputvoltagerippleapproaching1mVP-P
canbeachievedwhenceramicoutputcapacitorsareused.
Fixed frequency switching ensures a clean output free
from low frequency noise typically present with charge
pumpsolutions.Thelowimpedanceoutputremainswithin
1% of nominal during large load steps. The 36V switch
allows VIN to VOUT differential of up to 34V.
■
Disk Drive MR Head Bias
■
Digital Camera CCD Bias
■
LCD Bias
GaAs FET Bias
Local Low Noise/Low Impedance Negative Supply
■
■
The LT1931/LT1931A are available in the 5-lead ThinSOT
package.
, LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a
trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
U
TYPICAL APPLICATIO
C2
1µF
Efficiency
L1A
L1B
10µH
10µH
V
IN
5V
100
95
D1
90
85
80
75
70
65
60
55
50
V
V
SW
OUT
IN
–5V
SHDN
350mA
R1
C4
220pF
LT1931
GND
29.4k
C1
4.7µF
C3
22µF
NFB
R2
10k
C1: TAIYO YUDEN X5R JMK212BJ475MG
C2: TAIYO YUDEN X5R LMK212BJ105MG
C3: TAIYO YUDEN X5R JMK325BJ226MM
D1: ON SEMICONDUCTOR MBR0520
L1: SUMIDA CLS62-100
1931 F01
0
100 150 200 250 300 350
LOAD CURRENT (mA)
50
1931 TA01
Figure 1. 5V to –5V, 350mA Inverting DC/DC Converter
1931fa
1
LT1931/LT1931A
W W U W
U W
U
ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Note 1)
VIN Voltage .............................................................. 16V
SW Voltage ................................................–0.4V to 36V
NFB Voltage ............................................................. –2V
Current Into NFB Pin............................................ ±1mA
SHDN Voltage .......................................................... 16V
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range (Note 2) .. –40°C to 85°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
TOP VIEW
SW 1
GND 2
NFB 3
5 V
IN
4 SHDN
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
TJMAX = 125°C, θJA = 150°C/ W
S5 PART MARKING
ORDER PART NUMBER
LT1931ES5
LT1931AES5
LT1931IS5
LT1931AIS5
LTRA
LTSP
LTBZF
LTBZG
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are T = 25°C.
A
V
IN
= 3V, V
= V , unless otherwise noted. (Note 2)
SHDN
IN
LT1931
TYP
LT1931A
TYP
PARAMETER
CONDITIONS
MIN
MAX
2.6
MIN
MAX
2.6
UNITS
Minimum Operating Voltage
Maximum Operating Voltage
Feedback Voltage
2.45
2.45
V
V
16
16
–1.275 –1.255 –1.235 –1.275 –1.255 –1.235
V
V
●
●
–1.280
–1.230 –1.280
–1.230
NFB Pin Bias Current
V
V
V
= –1.255V
4
8
6
8
16
8
µA
mA
µA
NFB
Quiescent Current
= 2.4V, Not Switching
4.2
5.8
SHDN
SHDN
Quiescent Current in Shutdown
Reference Line Regulation
Switching Frequency
= 0V, V = 3V
0.01
0.01
1.2
1
0.01
0.01
2.2
1
IN
2.6V ≤ V ≤ 16V
0.05
0.05
%/V
IN
1
0.85
1.4
1.6
1.8
1.6
2.6
2.9
MHz
MHz
●
●
Maximum Duty Cycle
Switch Current Limit
84
1
90
1.2
75
1
82
1.2
%
A
(Note 3)
2
600
1
2.5
600
1
Switch V
I
= 1A
= 5V
400
0.01
400
0.01
mV
µA
V
CESAT
SW
Switch Leakage Current
SHDN Input Voltage, High
SHDN Input Voltage, Low
SHDN Pin Bias Current
V
SW
2.4
2.4
0.5
0.5
V
V
SHDN
V
SHDN
= 3V
= 0V
16
0
32
0.1
35
0
70
0.1
µA
µA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LT1931E/LT1931AE are guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls. LT1931I/LT1931AI are
guaranteed over the –40°C to 85°C temperature range.
Note 3: Current limit guaranteed by design and/or correlation to static test.
1931fa
2
LT1931/LT1931A
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Quiescent Current
Feedback Pin Voltage
Shutdown Pin Current
–1.28
–1.27
–1.26
–1.25
–1.24
–1.23
–1.22
7.0
6.5
6.0
5.5
90
80
70
60
50
40
30
20
10
0
NOT SWITCHING
T
= 25°C
A
LT1931A
LT1931A
LT1931
50
5.0
4.5
LT1931
4.0
3.5
3.0
–10
–50
0
25
50
75
100
–25
–25
0
–50
75
100
25
0
1
3
4
5
6
2
TEMPERATURE (°C)
SHDN PIN VOLTAGE (V)
TEMPERATURE (°C)
1931 G02
1931 G01
1931 G03
Current Limit
Switch Saturation Voltage
Oscillator Frequency
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
2.5
2.3
2.1
1.9
1.7
1.5
1.3
1.1
0.9
0.7
0.5
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
T
= 25°C
T
= 25°C
A
A
LT1931A
LT1931
0
–50
–25
25
50
75
100
0
50 60
0
0.2
0.4
0.6
1.2
10 20 30 40
70 80 90
0.8
1.0
TEMPERATURE (°C)
SWITCH CURRENT (A)
DUTY CYCLE (%)
1931 G06
1931 G04
1931 G05
U
U
U
PI FU CTIO S
SW (Pin 1): Switch Pin. Connect inductor/diode here.
| VOUT | –1.255
For LT1931A: R1=
Minimize trace area at this pin to keep EMI down.
1.255
+ 8 •10–6
(
)
R2
GND (Pin 2): Ground. Tie directly to local ground plane.
SHDN(Pin4):ShutdownPin.Tieto2.4Vormoretoenable
NFB (Pin 3): Feedback Pin. Reference voltage is –1.255V.
Connect resistive divider tap here. Minimize trace area.
The NFB bias current flows out of the pin. Set R1 and R2
according to:
device. Ground to shut down.
VIN (Pin 5): Input Supply Pin. Must be locally bypassed.
| VOUT | –1.255
For LT1931: R1=
1.255
+ 4 •10–6
(
)
R2
1931fa
3
LT1931/LT1931A
W
BLOCK DIAGRA
V
V
IN
5
IN
R5
80k
R6
80k
1
SW
+
–
COMPARATOR
A2
–
+
A1
m
DRIVER
g
LATCH
S
Q3
R
Q
R
C
RAMP
Q1
Q2
Σ
GENERATOR
x10
C
+
–
C
V
OUT
R3
30k
0.01Ω
1.2MHz
OSCILLATOR
R1
C
PL
(EXTERNAL)
R4
150k
(OPTIONAL)
NFB
SHDN
4
SHUTDOWN
3
NFB
2
GND
R2
1931 BD
(EXTERNAL)
Figure 2
U
OPERATIO
The LT1931 uses a constant frequency, current mode
control scheme to provide excellent line and load regula-
tion. Operation can be best understood by referring to the
Block Diagram in Figure 2. At the start of each oscillator
cycle, the SR latch is set, turning on the power switch Q3.
A voltage proportional to the switch current is added to a
stabilizing ramp and the resulting sum is fed into the
positive terminal of the PWM comparator A2. When this
voltageexceedsthelevelatthenegativeinputofA2,theSR
latch is reset, turning off the power switch. The level at the
negative input of A2 is set by the error amplifier (gm) and
is simply an amplified version of the difference between
thefeedbackvoltageandthereferencevoltageof–1.255V.
In this manner, the error amplifier sets the correct peak
current level to keep the output in regulation. If the error
amplifier’s output increases, more current is taken from
the output; if it decreases, less current is taken. One
function not shown in Figure 2 is the current limit. The
switch current is constantly monitored and not allowed to
exceed the nominal value of 1.2A. If the switch current
reaches 1.2A, the SR latch is reset regardless of the state
of comparator A2. This current limit protects the power
switch as well as various external components connected
to the LT1931.
TheBlockDiagramfortheLT1931Aisidenticalexceptthat
theoscillatoris2.2MHzandresistorsR3toR6areone-half
the LT1931 values.
1931fa
4
LT1931/LT1931A
W U U
APPLICATIO S I FOR ATIO
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LT1931A AND LT1931 DIFFERENCES:
corelossesatfrequenciesabove1MHzaremuchlowerfor
ferrite cores than for powdered-iron units. When using
coupled inductors, choose one that can handle at least 1A
of current without saturating, and ensure that the inductor
has a low DCR (copper-wire resistance) to minimize I2R
powerlosses. Ifusinguncoupledinductors, eachinductor
need only handle one-half of the total switch current so
that 0.5A per inductor is sufficient. A 4.7µH to 15µH
coupled inductor or a 15µH to 22µH uncoupled inductor
will usually be the best choice for most LT1931 designs.
For the LT1931A, a 2.2µH to 4.7µH coupled inductor or a
3.3µH to 10µH uncoupled inductor will usually suffice. In
certain applications such as the “Charge Pump” inverting
DC/DC converter, only a single inductor is used. In this
case, the inductor must carry the entire 1A switch current.
Switching Frequency
The key difference between the LT1931A and LT1931 is
thefasterswitchingfrequencyoftheLT1931A.At2.2MHz,
the LT1931A switches at nearly twice the rate of the
LT1931. Care must be taken in deciding which part to use.
The high switching frequency of the LT1931A allows
smaller cheaper inductors and capacitors to be used in a
given application, but with a slight decrease in efficiency
and maximum output current when compared to the
LT1931. Generally, if efficiency and maximum output
current are critical, the LT1931 should be used. If applica-
tion size and cost are more important, the LT1931A will be
the better choice. In many applications, tiny inexpensive
chip inductors can be used with the LT1931A, reducing
solution cost.
Table 1. Recommended Inductors—LT1931
L
Size
PART
(µH) (L × W × H) mm
VENDOR
Duty Cycle
CLS62-100
CR43-150
CR43-220
10
15
22
6.8 × 6.6 × 2.5
4.5 × 4.0 × 3.2
Sumida
(847) 956-0666
www.sumida.com
The maximum duty cycle (DC) of the LT1931A is 75%
compared to 84% for the LT1931. The duty cycle for a
given application using the dual inductor inverting topol-
ogy is given by:
CTX10-1
CTX15-1
10
15
8.9 × 11.4 × 4.2
3.2 × 2.5 × 2.0
Coiltronics
(407) 241-7876
www. coiltronics.com
LQH3C100K24
LQH4C150K04
10
15
Murata
(404) 436-1300
www.murata.com
| VOUT
|
DC =
| V | + | VOUT
|
IN
Table 2. Recommended Inductors—LT1931A
Size
(µH) (L × W × H) mm
For a 5V to –5V application, the DC is 50% indicating that
the LT1931A can be used. A 5V to –16V application has a
DC of 76.2% making the LT1931 the right choice. The
LT1931A can still be used in applications where the DC, as
calculated above, is above 75%. However, the part must
beoperatedinthediscontinuousconductionmodesothat
the actual duty cycle is reduced.
L
PART
VENDOR
ELJPC3R3MF
ELJPC4R7MF
3.3
4.7
2.5 × 2.0 × 1.6
7.6 × 4.8 × 1.8
2.0 × 1.6 × 1.6
3.2 × 2.5 × 2.0
Panasonic
(408) 945-5660
www.panasonic.com
1
2
CLQ4D10-4R7
CLQ4D10-6R8
4.7
6.8
Sumida
(847) 956-0666
www.sumida.com
LB20164R7M
LB20163R3M
4.7
3.3
Taiyo Yuden
(408) 573-4150
www.t-yuden.com
INDUCTOR SELECTION
SeveralinductorsthatworkwellwiththeLT1931arelisted
in Table 1 and those for the LT1931A are listed in Table 2.
Besides these, there are many other inductors that can be
used. Consult each manufacturer for detailed information
and for their entire selection of related parts. Ferrite core
inductors should be used to obtain the best efficiency, as
LQH3C4R7K24
LQH4C100K24
4.7
10
Murata
(404) 436-1300
www.murata.com
1
Use drawing #5382-T039
Use drawing #5382-T041
2
1931fa
5
LT1931/LT1931A
W U U
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APPLICATIO S I FOR ATIO
The inductors shown in Table 2 for use with the LT1931A
were chosen for their small size. For better efficiency, use
similar valued inductors with a larger volume. For in-
stance, the Sumida CR43 series, in values ranging from
3.3µH to 10µH, will give a LT1931A application a few
percentage points increase in efficiency.
zero to the system. For the tantalum and OS-CON capaci-
tors, this zero is located at a lower frequency due to the
higher value of the ESR, while the zero of a ceramic
capacitor is at a much higher frequency and can generally
be ignored.
A phase lead zero can be intentionally introduced by
placing a capacitor (C4) in parallel with the resistor (R1)
between VOUT and VNFB as shown in Figure 1. The
frequency of the zero is determined by the following
equation.
CAPACITOR SELECTION
Low ESR (equivalent series resistance) capacitors should
beusedattheoutputtominimizetheoutputripplevoltage.
Multilayer ceramic capacitors are an excellent choice, as
they have an extremely low ESR and are available in very
small packages. X5R dielectrics are preferred, followed by
X7R, as these materials retain their capacitance over wide
voltage and temperature ranges. A 10µF to 22µF output
capacitor is sufficient for most LT1931 applications while
a 4.7µF to 10µF capacitor will suffice for the LT1931A.
Solid tantalum or OS-CON capacitors can be used, but
they will occupy more board area than a ceramic and will
haveahigherESR. Alwaysuseacapacitorwithasufficient
voltage rating.
1
ƒZ =
2π •R1•C4
By choosing the appropriate values for the resistor and
capacitor, the zero frequency can be designed to improve
the phase margin of the overall converter. The typical
target value for the zero frequency is between 20kHz to
60kHz. Figure 3 shows the transient response of the
inverting converter from Figure 1 without the phase lead
capacitor C4. The phase margin is reduced as evidenced
by more ringing in both the output voltage and inductor
current. A 220pF capacitor for C4 results in better phase
margin, which is revealed in Figure 4 as a more damped
responseandlessovershoot. Figure5showsthetransient
response when a 22µF tantalum capacitor with no phase
lead capacitor is used on the output. The higher output
voltage ripple is revealed in the upper waveform as a
thicker line. The transient response is adequate which
implies that the ESR zero is improving the phase margin.
Ceramic capacitors also make a good choice for the input
decoupling capacitor, which should be placed as close as
possible to the LT1931/LT1931A. A 1µF to 4.7µF input
capacitorissufficientformostapplications.Table3shows
a list of several ceramic capacitor manufacturers. Consult
the manufacturers for detailed information on their entire
selection of ceramic parts.
Table 3. Ceramic Capacitor Manufacturers
Taiyo Yuden
(408) 573-4150
www.t-yuden.com
VOUT
20mV/DIV
AC COUPLED
AVX
(803) 448-9411
www.avxcorp.com
Murata
(714) 852-2001
www.murata.com
I
L1A + IL1B
0.5A/DIV
AC COUPLED
200mA
100mA
LOAD
CURRENT
ThedecisiontouseeitherlowESR(ceramic)capacitorsor
the higher ESR (tantalum or OS-CON) capacitors can
effect the stability of the overall system. The ESR of any
capacitor, along with the capacitance itself, contributes a
100µs/DIV
1931 F03
Figure 3. Transient Response of Inverting Converter
Without Phase Lead Capacitor
1931fa
6
LT1931/LT1931A
W U U
APPLICATIO S I FOR ATIO
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VOUT
20mV/DIV
AC COUPLED
VOUT
2V/DIV
IL1A + IL1B
0.5A/DIV
AC COUPLED
IIN
0.5A/DIV
AC COUPLED
200mA
100mA
LOAD
CURRENT
5V
0V
VSHDN
100µs/DIV
1931 F04
500µs/DIV
1931 F06
Figure 4. Transient Response of Inverting Converter
with 220pF Phase Lead Capacitor
Figure 6. Start-Up Waveforms for 5V to –5V Application
(Figure 1). No Soft-Start Circuit. V Reaches –5V in
OUT
500µs; Input Current Peaks at 800mA
VOUT
0.1V/DIV
regulatortriestochargeuptheoutputcapacitorasquickly
as possible, which results in a large inrush current. Fig-
ure 6 shows a typical oscillograph of the start-up wave-
form for the application of Figure 1 starting into a load of
33Ω. The lower waveform shows SHDN being pulsed
from 0V to 5V. The middle waveform shows the input
current, which reaches as high as 0.8A. The total time
required for the output to reach its final value is approxi-
mately 500µs. For some applications, this initial inrush
current may not be acceptable. If a longer start-up time is
acceptable, a soft-start circuit consisting of RSS and CSS,
as shown in Figure 7, can be used to limit inrush current
to a lower value. Figure 8 shows the relevant waveforms
with RSS = 15k and CSS = 33nF. Input current, measured
atVIN,islimitedtoapeakvalueof0.5Aasthetimerequired
to reach final value increases to 1ms. In Figure 9, CSS is
AC COUPLED
IL1A + IL1B
0.5A/DIV
AC COUPLED
200mA
100mA
LOAD
CURRENT
50µs/DIV
1931 F05
Figure 5. Transient Response of Inverting Converter with 22µF
Tantalum Output Capacitor and No Phase Lead Capacitor
START-UP/SOFT-START
For most LT1931/LT1931A applications, the start-up in-
rush current can be high. This is an inherent feature of
switching regulators in general since the feedback loop is
saturated due to VOUT being far from its final value. The
C2
CURRENT
PROBE
L1A
10µH
L1B
1µF
10µH
V
IN
5V
D1
+
V
IN
SW
C1
4.7µF
V
OUT
–5V
R1
29.4k
C4
220pF
R
LT1931
SS
15k
C3
22µF
V
SHDN
NFB
SS
GND
R2
10k
D2
1N4148
C
SS
C1: TAIYO YUDEN X5R JMK212BJ475MG
C2: TAIYO YUDEN X5R LMK212BJ105MG
C3: TAIYO YUDEN XR5 JMK325BJ226MM
D1: ON SEMICONDUCTOR MBR0520
L1: SUMIDA CLS62-100
33nF/68nF
1931 F07
V
OUT
Figure 7. R and C at SHDN Pin Provide Soft-Start to LT1931 Inverting Converter
SS
SS
1931fa
7
LT1931/LT1931A
W U U
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APPLICATIO S I FOR ATIO
DIODE SELECTION
VOUT
2V/DIV
ASchottkydiodeisrecommendedforusewiththeLT1931/
LT1931A. The Motorola MBR0520 is a very good choice.
Wheretheinputtooutputvoltagedifferentialexceeds20V,
use the MBR0530 (a 30V diode). These diodes are rated to
handleanaverageforwardcurrentof0.5A. Inapplications
where the average forward current of the diode exceeds
0.5A, a Microsemi UPS5817 rated at 1A is recommended.
IIN
0.5A/DIV
AC COUPLED
5V
0V
VSS
200µs/DIV
1931 F08
Figure 8. R = 15k, C = 33nF; V Reaches –5V in 1ms;
OUT
Input Current Peaks at 500mA
SS
SS
LAYOUT HINTS
The high-speed operation of the LT1931/LT1931A de-
mands careful attention to board layout. You will not get
advertised performance with careless layout. Figure 10
shows the recommended component placement. The
ground cut at the cathode of D1 is essential for low noise
operation.
VOUT
2V/DIV
IIN
0.5A/DIV
AC COUPLED
5V
0V
VSS
500µs/DIV
1931 F09
Figure 9. R = 15k, C = 68nF; V Reaches –5V in 1.6ms;
OUT
SS
SS
L1A
L1B
C2
Input Current Peaks at 350mA
C1
–V
OUT
+
increased to 68nF, resulting in a lower peak input current
of 350mA with a VOUT ramp time of 1.6ms. CSS or RSS can
be increased further for an even slower ramp, if desired.
Diode D2 serves to quickly discharge CSS when VSS is
driven low to shut down the device. D2 can be omitted,
resulting in a “soft-stop” slow discharge of the output
capacitor.
D1
V
IN
C3
+
1
2
3
5
4
SHUTDOWN
R2
R1
GND
1931 F10
Figure 10. Suggested Component Placement.
Note Cut in Ground Copper at D1’s Cathode
1931fa
8
LT1931/LT1931A
U
TYPICAL APPLICATIO S
5V to –12V Inverting Converter
Efficiency
100
95
90
85
80
75
70
65
60
55
50
C2
L1A
1µF
L1B
10µH
10µH
V
IN
5V
D1
V
V
SW
OUT
IN
–12V
SHDN
LT1931
150mA
R1
84.5k
C1
4.7µF
C3
10µF
NFB
GND
R2
10k
C1: TAIYO YUDEN X5R JMK212BJ475MG
C2: TAIYO YUDEN X5R TMK316BJ105ML
C3: TAIYO YUDEN X5R EMK325BJ106MM
D1: ON SEMICONDUCTOR MBR0520
L1: SUMIDA CLS62-100
1931 TA02
0
25
75
100
125
150
50
LOAD CURRENT (mA)
1931 TA03
5V to –5V Inverting Converter Using Uncoupled Inductors
C2
1µF
L1
10µH
L2
10µH
V
IN
5V
D1
V
V
SW
OUT
IN
–5V
SHDN
300mA
R1
220pF
LT1931
GND
29.4k
C1
4.7µF
C3
22µF
NFB
R2
10k
C1: TAIYO YUDEN X5R JMK212BJ475MG
C2: TAIYO YUDEN X5R LMK212BJ105MG
C3: TAIYO YUDEN X5R JMK212BJ226MM
D1: ON SEMICONDUCTOR MBR0520
L1, L2: MURATA LQH3C100K04
1931 TA04
2.2MHz, 5V to –5V Inverting Converter
Efficiency
C2
80
75
70
65
60
55
50
L1
L2
4.7µH
1µF
4.7µH
V
IN
5V
D1
V
V
IN
SW
OUT
–5V
SHDN
300mA
R1
C4
180pF
LT1931A
GND
28.7k
C1
4.7µF
C3
4.7µF
NFB
R2
10k
C1: TAIYO YUDEN X5R JMK212BJ475MG
C2: TAIYO YUDEN X5R LMK212BJ105MG
C3: TAIYO YUDEN X5R JMK212BJ475MG
D1: ON SEMICONDUCTOR MBR0520
L1, L2: MURATA LQH3C4R7M24
1931 TA05a
0
100 150 200 250 300 350
LOAD CURRENT (mA)
50
1931 TA05b
1931fa
9
LT1931/LT1931A
TYPICAL APPLICATIO S
U
2.2MHz, 5V to –5V Converter Uses Tiny Chip Inductors
Efficiency
C2
1µF
80
75
L1
3.3µH
L2
3.3µH
V
IN
5V
D1
V
V
SW
70
65
OUT
IN
–5V
SHDN
200mA
R1
C4
68pF
LT1931A
GND
28.7k
C1
2.2µF
C3
4.7µF
NFB
60
55
50
R2
10k
C1: TAIYO YUDEN X5R JMK212BJ225MG
C2: TAIYO YUDEN X5R LMK212BJ105MG
C3: TAIYO YUDEN X5R JMK212BJ475MG
D1: ON SEMICONDUCTOR MBR0520
L1, L2: PANASONIC ELJPC3R3MF
1931 TA06a
0
50
100
150
200
250
LOAD CURRENT (mA)
1931 TA06b
SLIC Power Supply with –33V and –68V Outputs, Uses Soft-Start
L1
22µH
R1
1Ω
V
IN
12V
C2
C1
4.7µF
16V
1µF
V
SW
35V
IN
D1
R
SS
15k
LT1931
3
2
1
COM
C4
SHDN
NFB
V
SS
4.7µF
GND
35V
V
OUT1
–33V
R2
1k
R3
25.5k
C
SS
100mA*
68nF
C3
1µF
35V
C6
1000pF
R4
2.7k
D2
3
2
1
C5
4.7µF
35V
*TOTAL OUTPUT POWER NOT TO EXCEED 3.3W
C1 TO C5: X5R OR X7R
D1, D2: BAV99 OR EQUIVALENT
L1: SUMIDA CR43-220
V
OUT2
–66V
1931 TA08
48mA*
1931fa
10
LT1931/LT1931A
U
TYPICAL APPLICATIO S
SLIC Power Supply with –21.6V and –65V Outputs, Uses Soft-Start
L1
10µH
R1
1Ω
V
IN
5V
C1
C2
1µF
35V
4.7µF
16V
V
IN
SW
D1
R
SS
15k
3
2
1
LT1931
SHDN
COM
C5
4.7µF
25V
NFB
V
SS
GND
V
OUT1
–21.6V
48mA*
R2
1k
R3
16.2k
C3
1µF
35V
C8
1000pF
C
SS
68nF
R4
2.7k
D2
D3
3
2
1
C6
4.7µF
25V
*TOTAL OUTPUT POWER NOT TO EXCEED 1.3W
C1 TO C7: X5R OR X7R
D1, D2: BAV99 OR EQUIVALENT
L1: SUMIDA CR43-100
C4
1µF
35V
3
2
1
C7
4.7µF
25V
V
OUT2
–65V
1931 TA09
20mA*
U
PACKAGE DESCRIPTIO
S5 Package
5-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1635)
0.62
MAX
0.95
REF
2.90 BSC
(NOTE 4)
1.22 REF
1.50 – 1.75
(NOTE 4)
2.80 BSC
1.4 MIN
3.85 MAX 2.62 REF
PIN ONE
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45 TYP
5 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
DATUM ‘A’
0.01 – 0.10
1.00 MAX
0.30 – 0.50 REF
1.90 BSC
0.09 – 0.20
(NOTE 3)
NOTE:
S5 TSOT-23 0302 REV B
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
1931fa
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 represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
11
LT1931/LT1931A
U
TYPICAL APPLICATIO
2.2MHz, 12V to –5V Converter Uses Low Profile Coupled Inductor
C2
0.1µF
L1A
4.7µH
L1B
4.7µH
V
IN
12V
D1
V
V
SW
OUT
IN
–5V
SHDN
450mA
R1
28.7k
LT1931A
C1
2.2µF
C3
4.7µF
NFB
GND
R2
10k
C1: TAIYO YUDEN Y5V EMK212F225ZG
C2: 0.1µF 25V X5R
1931 TA07a
C3: TAIYO YUDEN X5R JMK212BJ475MG
D1: ON SEMICONDUCTOR MBR0520
L1: SUMIDA CLQ4D10-4R7 DRAWING #5382-T039
Efficiency
80
75
70
65
60
55
50
0
100
200
300
400
500
LOAD CURRENT (mA)
1931 TA07b
RELATED PARTS
PART NUMBER
LT1307
DESCRIPTION
COMMENTS
Single Cell Micropower 600kHz PWM DC/DC Converter
3.3V at 75mA from One Cell, MSOP Package
1.5V Minimum, Precise Control of Peak Current Limit
3.3V at 200mA from Two Cells, 600kHz Fixed Frequency
3V at 30mA from 1V, 1.7MHz Fixed Frequency
–5V at 150mA from 5V Input. Tiny SOT-23 Package
5V at 200mA from 3.3V Input. Tiny SOT-23 Package
20V at 12mA from 2.5V. Tiny SOT-23 Package
–15V at 12mA from 2.5V. Tiny SOT-23 Package
5V at 450mA from 3.3V Input. Tiny SOT-23 Package
LT1316
Burst ModeTM Operation DC/DC with Programmable Current Limit
2-Cell Micropower DC/DC with Low-Battery Detector
Single Cell Micropower DC/DC Converter
LT1317
LT1610
LT1611
Inverting 1.4MHz Switching Regulator in 5-Lead ThinSOT
1.4MHz Switching Regulator in 5-Lead ThinSOT
LT1613
LT1615
Micropower Constant Off-Time DC/DC Converter in 5-Lead ThinSOT
Micropower Inverting DC/DC Converter in 5-Lead ThinSOT
1.2MHz/2.2MHz, 1A Switching Regulators in 5-Lead ThinSOT
LT1617
LT1930/LT1930A
Burst Mode operation is a trademark of Linear Technology Corporation.
1931fa
LT/LT 1005 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
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(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
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