LINER LTC1574_1

LTC1574
LTC1574-3.3/LTC1574-5
High Efficiency Step-Down
DC/DC Converters
with Internal Schottky Diode
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FEATURES
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DESCRIPTIO
High Efficiency: Up to 94%
Usable in Noise-Sensitive Products
Peak Inductor Current Independent of Inductor Value
Short-Circuit Protection
Internal Low Forward Drop Schottky Diode
Only Three External Components Required
Wide VIN Range: 4V to 18.5V (Absolute Maximum)
Low Dropout Operation
Low-Battery Detector
Pin Selectable Current Limit
Internal 0.9Ω Power Switch: VIN < 11V
Standby Current: 130µA
Active Low Micropower Shutdown
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APPLICATIO S
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The LTC®1574 is a family of easy-to-use current mode
DC/DC converters ideally suited for 9V to 5V, 5V to 3.3V
and inverting operation. With an internal 0.9Ω switch (at
a supply voltage of 12V) and a low forward drop Schottky
diode (0.450V typ at 200mA, TA = 25°C), the LTC1574
requires only three external components to construct a
complete high efficiency DC/DC converter.
Under no load condition, the LTC1574 draws only 130µA.
In shutdown, it draws a mere 2µA making this converter
ideal for battery-powered applications. In dropout, the
internal P-channel MOSFET switch is turned on continuously allowing the user to maximize the life of the battery
source.
The maximum inductor current of the LTC1574 family is
pin selectable to either 340mA or 600mA, optimizing
efficiency for a wide range of applications. Operation up to
200kHz permits the use of small surface mount inductors
and capacitors.
Inverting Converters
Step-Down Converters
Memory Backup Supply
Portable Instruments
Battery-Powered Equipment
Distributed Power Systems
and LTC are registered trademarks and LT is a trademark of Linear Technology Corporation.
For applications requiring higher output current or ultrahigh efficiency, see the LTC1148 or LTC1265 data sheets.
For detailed applications information, see the LTC1174
data sheet.
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TYPICAL APPLICATIO
LTC1574-5 Efficiency
High Efficiency Step-Down Converter
VIN
5.5V to
16V
100
L = 100µH
VOUT = 5V
IPGM = 0V
+
5
VIN
12
11
6
SHDN
LBIN
LTC1574-5
VOUT
LBOUT
IPGM
SW
7
10
3, 14
100µH†
+
GND
22µF*
35V
2, 4, 13, 15
5V
175mA
100µF*
10V
1574 TA01
* AVX TPSD226K035
** AVX TPSD107K010
† COILTRONICS CTX100-4
EFFICIENCY (%)
95
VIN = 6V
90
VIN = 9V
85
80
75
70
1
10
LOAD CURRENT (mA)
100 200
1574 TA02
1
LTC1574
LTC1574-3.3/LTC1574-5
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PACKAGE/ORDER I FOR ATIO
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ABSOLUTE
RATI GS
(Note 1)
(Voltage Referred to GND Pin)
Input Supply Voltage (Pin 5) ................. – 0.3V to 18.5V
Switch Current (Pin 3, 14) ........................................ 1A
Switch Voltage (Pin 3, 14) .......................... VIN – 18.5V
Operating Temperature Range .................... 0°C to 70°C
Junction Temperature (Note 2) ............................ 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
TOP VIEW
NC 1
GND 2
15 GND
SW 3
14 SW
GND 4
13 GND
VIN 5
12 LBIN
IPGM 6
SHDN 7
NC 8
ORDER PART
NUMBER
16 NC
LTC1574CS
LTC1574CS-3.3
LTC1574CS-5
11 LBOUT
10 VOUT (VFB*)
9
NC
S PACKAGE
16-LEAD PLASTIC SO
*ADJUSTABLE OUTPUT VERSION
TJMAX = 125°C, θJA = 110°C/W
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 9V, SHDN = VIN, IPGM = 0V, unless otherwise specified.
SYMBOL PARAMETER
CONDITIONS
IFB
Feedback Current into Pin 10
LTC1574
VFB
Feedback Voltage
LTC1574
●
1.20
VOUT
Regulated Output Voltage
LTC1574-3.3
LTC1574-5
●
●
3.14
4.75
∆VOUT
Output Voltage Line
Regulation
Output Voltage Load
Regulation
IQ
Input DC Supply Current (Note 4)
Active Mode
Sleep Mode
Shutdown (Note 5)
MIN
MAX
UNITS
1
µA
1.25
1.30
V
3.30
5.00
3.46
5.25
V
V
VIN = 6V to 12V, ILOAD = 100mA, IPGM = VIN (Note 3)
10
70
mV
LTC1574-3.3 (Note 3)
20mA < ILOAD < 175mA, IPGM = 0V
20mA < ILOAD < 400mA, IPGM = VIN
–5
– 45
– 70
– 70
mV
mV
LTC1574-5 (Note 3)
20mA < ILOAD < 175mA, IPGM = 0V
20mA < ILOAD < 400mA, IPGM = VIN
–5
– 50
– 70
– 70
mV
mV
450
130
2
600
180
25
µA
µA
µA
1.25
1.4
V
0.5
µA
4V < VIN < 16V, IPGM = 0V
4V < VIN < 16V
SHDN = 0V, 4V < VIN < 16V
VLBTRIP
Low-Battery Trip Point
ILBIN
Current into Pin 12
ILBOUT
Current Sunk by Pin 11
VHYST
Comparator Hysteresis
IPEAK
Current Limit
RON
ON Resistance of Switch
tOFF
Switch Off Time
VOUT at Regulated Value
VIH
SHDN Pin High
Minimum Voltage at Pin 7 for Device to Be Active
VIL
SHDN Pin Low
Maximum Voltage at Pin 7 for Device to Be in Shutdown
2
TYP
VLBOUT = 0.4V, VLBIN = 0V
VLBOUT = 5V, VLBIN = 10V
IPGM = VIN, VOUT = 0V
IPGM = 0V, VOUT = 0V
●
●
0.5
1.0
1.5
1.0
mA
µA
7.5
15
30
mV
0.54
0.27
0.60
0.34
0.83
0.53
A
A
0.9
1.55
Ω
4
5
µs
●
3
1.2
V
0.75
V
LTC1574
LTC1574-3.3/LTC1574-5
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 9V, SHDN = VIN, IPGM = 0V, unless otherwise specified.
SYMBOL PARAMETER
CONDITIONS
MIN
IIH
SHDN Pin Input Current
SHDN = 16V
IIL
SHDN Pin Input Current
0 ≤ SHDN ≤ 0.8V
VF
Schottky Diode Forward Voltage
Forward Current = 200mA
IR
Schottky Reverse Current
Reverse Voltage = 5V
Reverse Voltage = 18.5V
TYP
MAX
UNITS
2
µA
0.5
µA
0.450
0.570
V
10
100
25
250
µA
µA
Note 3: Guaranteed by design.
Note 4: Does not include Schottky reverse current. Dynamic supply
current is higher due to the gate charge being delivered at the switching
frequency.
Note 5: Current into Pin 5 only, measured without electrolytic input
capacitor.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: TJ is calculated from the ambient temperature TA and power
dissipation PD according to the following formulas:
TJ = TA + (PD • 110°C/W)
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TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Load Current
Efficiency vs Load Current
EFFICIENCY (%)
EFFICIENCY (%)
VIN = 5V
90
VIN = 9V
80
70
L = 50µH
VOUT = 3.3V
IPGM = VIN
COIL = CTX50-4
60
Efficiency vs Input Voltage
100
95
95
94
VIN = 9V
85
80
L = 50µH
VOUT = 5V
IPGM = VIN
COIL = CTX50-4
75
1
10
100
LOAD CURRENT (mA)
1
500
10
100
LOAD CURRENT (mA)
Efficiency Using Different Types
of Inductor Core Material
180
CTX50-4P
80
70
VIN = 5V
VOUT = 3.3V
IPGM = VIN
5
500
6
8
9 10 11 12
INPUT VOLTAGE (V)
7
13
14
1574 • TPC03
1.7
VIN = 13.5V
160
1.6
140
1.5
120
1.4
100
80
60
TA = 25°C
1.3
1.2
1.1
1.0
40
0.9
0.8
0
10
100
LOAD CURRENT (mA)
91
Switch Resistance vs
Input Voltage
20
50
ILOAD = 100mA
IPGM = 0V
89
400
RDS(ON) (Ω)
EFFICIENCY (%)
LEAKAGE CURRENT (nA)
CTX50-4
1
ILOAD = 300mA
IPGM = VIN
Switch Leakage Current
vs Temperature
100
60
92
1574 • TPC02
1574 • TPC01
90
93
90
70
50
VOUT = 5V
L = 100µH
COIL = CTX100-4
VIN = 6V
90
EFFICIENCY (%)
100
0
20
40
60
TEMPERATURE (°C)
80
100
1574 • TPC04
1574 • TPC05
0.7
4
6
8
10 12 14 16
INPUT VOLTAGE (V)
18
20
1574 • TPC06
3
LTC1574
LTC1574-3.3/LTC1574-5
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NC (Pins 1, 8, 9, 16): No Connection.
GND (Pins 2, 4, 13, 15): Ground.
SW (Pins 3, 14): Drain of P-Channel MOSFET Switch and
Cathode of Schottky Diode.
VOUT or VFB (Pin 10): For the LTC1574, this pin connects
to the main voltage comparator input. On the LTC1574-5
and LTC1574-3.3, this pin goes to an internal resistive
divider which sets the output voltage.
VIN (Pin 5): Input Supply Voltage. It must be decoupled
close to ground (Pin 4).
LBOUT (Pin 11): Open drain of an N-Channel Pull-Down.
This pin will sink current when (Pin 12) LBIN goes below
1.25V.
IPGM (Pin 6): This pin selects the current limit of the
P-channel switch. With IPGM = VIN, the current trip point is
600mA and with IPGM = 0V, the current trip point is
reduced to 340mA.
LBIN (Pin 12): The (–) Input of the Low-Battery Voltage
Comparator. The (+) input is connected to a reference
voltage of 1.25V.
SHDN (Pin 7): Pulling this pin to ground keeps the internal
switch off and puts the LTC1574 in micropower shutdown.
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APPLICATIO S I FOR ATIO
Operating Frequency and Inductor
Since the LTC1574 utilizes a constant off-time architecture,
its operating frequency is dependent on the value of VIN. The
frequency of operation can be expressed as:
1  VIN − VOUT 


t OFF  VIN + VD 
(Hz)
where tOFF = 4µs and VD is the voltage drop across the
internal Schottky diode. Note that the operating frequency
is a function of the input and output voltage.
Although the size of the inductor does not affect the frequency or inductor peak current, it does affect the ripple
current. The peak-to-peak ripple current is given by:
IPGM = VIN
100mA/DIV
f=
IPGM pin, the limit is either set to 340mA or 600mA. In
addition, the off-time of the switch is increased to allow the
inductor current to decay far enough to prevent any current
build-up (see Figure 1).
IPGM = 0
GND
V
+ VD 
IRIPPLE = 4 • 10 −6  OUT

L


(AP-P )
When choosing a small inductor, core loss will increase due
to higher ripple current. Therefore, a low ESR output
capacitor has to be used.
Short-Circuit Protection
The LTC1574 is protected from output short circuits by its
internal current limit. Depending on the condition of the
4
L = 100µH
VIN = 13.5V
20µs/DIV
1574 • F01
Figure 1. Inductor Current with Output Shorted
Low-Battery Detector
The low-battery indicator senses the input voltage through
an external resistive divider. This divided voltage connects
to the “–” input of a voltage comparator (Pin 12) which is
compared with a 1.25V reference voltage. With the current
LTC1574
LTC1574-3.3/LTC1574-5
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APPLICATIO S I FOR ATIO
going into Pin 12 being negligible, the following expression is used for setting the trip limit:
 R4 
VLBTRIP = 1.251 + 
 R3 
VIN
LTC1574
R4
12
difference between the absolute maximum voltage rating
and the output voltage. A maximum of 12V is specified in
Figure 4, giving the circuit 1.5V of headroom for VIN. Note
that the circuit can operate from a minimum of 4V,
making it ideal for a four NiCd cell application. For a
higher output current circuit, please refer to the Typical
Applications section.
INPUT VOLTAGE
4V TO 12V
–
+
R3
5
1.25V
REFERENCE
VIN
1574 • F02
12
Figure 2. Low-Battery Comparator
11
LTC1574 Adjustable Applications
6
The LTC1574 develops a 1.25V reference voltage between
the feedback terminal (Pin 10) and ground (see Figure 3).
By selecting resistor R1, a constant current is caused to
flow through R1 and R2 to set the overall output voltage.
The regulated output voltage is determined by:
VOUT
47µF*
16V
×2
+
47µF*
16V
×2
LTC1574-5
7
SHDN
LBOUT
10
VOUT
IPGM
3, 14
SW
50µH**
GND
2, 4, 13, 15
* AVX TPSD476K016
** COILTRONICS CTX50-4
VOUT
–5V
45mA
1574 • F04
Figure 4. Positive-to-Negative 5V Converter
Low Noise Regulators
 R2 
= 1.25 1 + 
 R1
For most applications, a 30k resistor is suggested for R1.
To prevent stray pickup, a 100pF capacitor is suggested
across R1 located close to the LTC1574.
VOUT
R2
LTC1574
VFB
LBIN
+
0.1µF
10
100pF
R1
In some applications it is important not to introduce any
switching noise within the audio frequency range. Due to
the nature of the LTC1574 during Burst ModeTM operation,
there is a possibility that the regulator will introduce audio
noise at some load currents. To circumvent this problem,
a feed-forward capacitor can be used to shift the noise
spectrum up and out of the audio band. Figure 5 shows the
low noise connection with C2 being the feed-forward
capacitor. The peak-to-peak output ripple is reduced to
30mV over the entire load range. A toroidal surface mount
Burst Mode is a trademark of Linear Technology Corporation
1574 • F03
+
5
VIN
Figure 3. LTC1574 Adjustable Configuration
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Inverting Applications
The LTC1574 can easily be set up for a negative output
voltage. If – 5V is desired, the LTC1574-5 is ideal for this
application as it requires the least components. Figure 4
shows the schematic for this application. Note that the
output voltage is now taken off the GND pins. Therefore,
the maximum input voltage is now determined by the
11
6
LTC1574
SHDN
LBIN
LBOUT
SW
IPGM
VFB
7
3, 14
10
L1**
100µH
56k
C2
6.8nF
+
GND
2, 4, 13, 15
VIN
5V
100µF*
10V
33k
* AVX TPSD107K010
** COILTRONICS CTX100-4
VOUT
3.3V
425mA
100µF*
10V
1574 • F05
Figure 5. Low Noise 5V to 3.3V Regulator
5
LTC1574
LTC1574-3.3/LTC1574-5
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APPLICATIO S I FOR ATIO
inductor L1 is chosen for its excellent self-shielding properties. Open magnetic structures such as drum and rod
cores are to be avoided since they inject high flux levels
into their surroundings. This can become a major source
of noise in any converter circuit.
For COUT, the RMS current rating should be at least:
Design Example
Absolute Maximum Ratings and Latchup Prevention
As a design example, assume VIN = 9V (nominal),
VOUT = 5V and IOUT = 350mA maximum. The LTC1574-5
is used for this application with IPGM (Pin 6) connected to
VIN. The minimum value of L is determined by assuming
the LTC1574-5 is operating in continuous mode.
The absolute maximum ratings specify that SW
(Pins 3, 14) can never exceed VIN (Pin 5) by more than
0.3V. Normally this situation should never occur. It could,
however, if the output is held up while the supply is pulled
down. A condition where this could potentially occur is
when a battery is supplying power to an LTC1574 regulator and also to one or more loads in parallel with the the
regulator’s VIN. If the battery is disconnected while the
LTC1574 regulator is supplying a light load and one of the
parallel circuits is a heavy load, the input capacitor of the
LTC1574 regulator could be pulled down faster than the
output capacitor, causing the absolute maximum ratings
to be exceeded. The result is often a latchup which can be
destructive if VIN is reapplied. Battery disconnect is possible as a result of mechanical stress, bad battery contacts
or use of a lithium-ion battery with a built-in internal
disconnect. The user needs to assess his/her application
to determine whether this situation could occur. If so,
additional protection is necessary.
INDUCTOR CURRENT
IPEAK
AVG CURRENT = IOUT
I
+I
= PEAK V
IV
2
= 350mA
TIME
1574 • F06
Figure 6. Continuous Inductor Current
With IOUT = 350mA and IPEAK = 0.6A (IPGM = VIN), IV = 0.1A.
The peak-to-peak ripple inductor current, IRIPPLE, is 0.5A
and is also equal to:
V
+ VD 
IRIPPLE = 4 • 10 −6  OUT

L


(AP-P )
Solving for L in the above equation and with VD = 0.5V,
L = 44µH. The next higher standard value of L is 50µH
(example: Coiltronics CTX50-4). The operating frequency,
ignoring voltage across diode VD is:
 V 
f ≈ 2.5 • 105 1 − OUT 
VIN 

= 111kHz
With the value of L determined, the requirements for CIN
and COUT are calculated. For CIN, its RMS current rating
should be at least:
IRMS =
[
= 174mA
6
(
IOUT VOUT VIN − VOUT
VIN
)]
IRMS ≈
I PEAK
2
= 300mA
(A RMS)
Prevention against latchup can be accomplished by
simply connecting a Schottky diode across the SW and
VIN pins as shown in Figure 7. The diode will normally be
reverse biased unless VIN is pulled below VOUT at which
time the diode will clamp the (VOUT – VIN) potential to less
than the 0.6V required for latchup. Note that a low
leakage Schottky should be used to minimize the effect
LATCHUP
PROTECTION
SCHOTTKY
VIN
VOUT
SW
LTC1574
+
1/ 2
(A RMS)
1574 F07
Figure 7. Preventing Absolute Maximum
Ratings from Being Exceeded
LTC1574
LTC1574-3.3/LTC1574-5
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APPLICATIO S I FOR ATIO
on no-load supply current. Schottky diodes such as
MBR0530, BAS85 and BAT84 work well. Another more
serious effect of the protection diode leakage is that at no
load with nothing to provide a sink for this leakage
current, the output voltage can potentially float above the
maximum allowable tolerance. To prevent this from
occuring, a resistor must be connected between VOUT
and ground with a value low enough to sink the maximum
possible leakage current.
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TYPICAL APPLICATIO S
Low Noise, High Efficiency 3.3V Regulator
VIN
4V TO 12.5V
+
5
VIN
6
IPGM
SHDN
LTC1574
12
11
LBIN
VFB
LBOUT
SW
7
22µF*
25V
×2
10
3, 14
50µH†
6.8nF
+
GND
2, 4, 13, 15
100pF
* AVX TPSD226K025
** AVX TPSD107K010
†
COILTRONICS CTX50-4
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PACKAGE DESCRIPTIO
0.1µF
100µF**
10V
×2
VOUT
3.3V
450mA
56k
33k
1574 TA03
Dimension in inches (millimeters) unless otherwise noted.
S Package
16-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.386 – 0.394*
(9.804 – 10.008)
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
16
15
14
13
12
11
10
9
0° – 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.014 – 0.019
(0.355 – 0.483)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.050
(1.270)
BSC
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
S16 1098
1
2
3
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
4
5
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8
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LTC1574
LTC1574-3.3/LTC1574-5
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TYPICAL APPLICATIO S
Low Dropout 5V Step-Down Regulator
with Low-Battery Detection
High Efficiency 3.3V Regulator
VIN
5.5V to 12.5V
VIN
4V TO 12.5V
5
4.7k
VIN
*LOWBATTERY
INDICATOR
6
11
162k
0.1µF
12
SHDN
IPGM
LTC1574-5
LBOUT
VOUT
LBIN
SW
7
3, 14
L1
100µH†
+
2, 4, 13, 15
VIN
6
12
11
47µF**
16V
×2
7
SHDN
LTC1574-3.3
10
LBIN
VOUT
IPGM
LBOUT
SW
3, 14
22µF*
25V
×2
0.1µF
VOUT
3.3V
425mA
50µH†
+
GND
2, 4, 13, 15
* AVX TPSD226K025
** AVX TPSD476K016
†
COILTRONICS CTX50-4
1574 TA04
* LOW-BATTERY INDICATOR IS
SET UP TO TRIP AT VIN = 5.5V
** AVX TPSD476K016
+
5
47µF**
16V
×2
VOUT
5V
365mA
10
GND
47.5k
+
47µF*
16V
×2
1574 TA05
† SELECTION
MANUFACTURER
COILTRONICS
SUMIDA
GOWANDA
PART NO.
CTX100-4
CD75-101
GA10-103K
TYPE
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
Positive to – 5V Converter
VIN
4V TO 12.5V
*LOWBATTERY
INDICATOR
† SELECTION
280k
MANUFACTURER
COILTRONICS
COILCRAFT
SUMIDA
GOWANDA
PART NO.
CTX50-3
DT3316-473
CD54-470
GA10-472K
5
4.7k
* LOW-BATTERY INDICATOR IS
SET TO TRIP AT VIN = 4.4V
** AVX TPSD106K035
*** AVX TPSD107K010
TYPE
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
6
11
12
43k
0.1µF
VIN
IPGM
SHDN
LTC1574-5
VOUT
LBOUT
LBIN
SW
GND
+
7
10µF**
35V
×2
10
VIN (V)
4
6
8
10
12.5
IOUT (mA)
110
140
170
200
235
3, 14
L1†
50µH
+
2, 4, 13, 15
100µF***
10V
VOUT
–5V
1574 TA06
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT®1074/LT1076
Step-Down Switching Regulator
100kHz, 5A (LT1074) or 2A (LT1076) Monolithic
LTC1147
High Efficiency Step-Down DC/DC Controller
8-Pin Controller
LTC1174
High Efficiency Step-Down and Inverting DC/DC Converter 0.5A, Burst Mode Operation, SO-8 Package, VIN to 18V
LTC1265
1.2A High Efficiency Step-Down DC/DC Regulator
Burst Mode Operation, Monolithic
LT1375/LT1376
1.5A 500kHz Step-Down Switching Regulator
High Frequency Small Inductor
LT1611
Inverting 1.4MHz Switching Regulator in SOT-23
– 5V at 150mA from 5V Input, 1mVP-P Output Ripple, SOT-23 Package
LTC1701
1MHz Step-Down DC/DC Converter in SOT-23
VIN = 2.5V to 5.5V, IQ = 135µA, VOUT = 5V to 1.25V
LTC1707
High Efficiency Synchronous Step-Down Regulator
VIN = 2.85V to 8.5V, Selectable Burst Mode Operation,
600mA Output Current, SO-8 Package
LTC1877/LTC1878 High Efficiency Synchronous Step-Down Regulator
8
Linear Technology Corporation
600mA at VIN = 5V, 2.65V to 10V = VIN, IQ = 10µA
sn1574 1574fas LT/TP 1000 2K REV A • PRINTED IN
1630 McCarthy Blvd., Milpitas, CA 95035-7417
USA
(408)432-1900 FAX: (408) 434-0507 www.linear-tech.com
 LINEAR TECHNOLOGY CORPORATION 1995
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