Page 1
FEATURES
LOAD CURRENT (mA)
1
EFFICIENCY (%)
100
95
90
85
80
75
70
10 100
1174 TA02
200
VIN = 6V
V
IN
= 9V
L = 100µH
V
OUT
= 5V
I
PGM
= 0V
■
High Efficiency: Up to 94%
■
Peak Inductor Current Independent of
Inductor Value
■
Short-Circuit Protection
■
Optimized for 5V to – 5V Applications
■
Wide VIN Range: 4V to 18.5V
■
Low Dropout Operation
■
Low-Battery Detector
■
Pin Selectable Current Limit
■
Internal 0.9Ω Power Switch: VIN = 9V
■
Only Four External Components Required
■
130µA Standby Current
■
Active Low Micropower Shutdown
U
APPLICATIO S
■
Distributed Power Systems
■
Step-Down Converters
■
Inverting Converters
■
Memory Backup Supply
■
Portable Instruments
■
Battery-Powered Equipment
LTC1174
LTC1174-3.3/LTC1174-5
High Efficiency
Step-Down and Inverting
DC/DC Converter
U
DESCRIPTIO
®
The LTC
ideally suited for 9V to 5V, 5V to 3.3V or 5V to –5V
operation. With an internal 0.9Ω switch (at a supply
voltage of 9V), the LTC1174 requires only four external
components to construct a complete high efficiency
DC/DC converter.
Under a no load condition the LTC1174 draws only 130µA.
In shutdown, it draws a mere 1µA making this converter
ideal for current sensitive 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 LTC1174 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.
For applications requiring higher output current or ultrahigh efficiency, see the LTC1148 data sheet.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
1174 is a simple current mode DC/DC converter
TYPICAL APPLICATIO
High Efficiency Step-Down Converter
V
IN
9V
3
2
7
(3) AVX TPSD156K025
*
AVX TPSD107K010
**
†
COILTRONICS CTX100-4
LB
LB
I
PGM
V
SHUTDOWN
IN
OUT
LTC1174-5
GND
6
IN
4
8
1
V
OUT
5
SW
U
100µH
1N5818
LTC1174-5 Efficiency
15µF*
+
25V
×3
†
+
5V
175mA
100µF**
10V
1174 TA01
1174fe
1
Page 2
LTC1174
LTC1174-3.3/LTC1174-5
WWWU
ABSOLUTE AXI U RATI GS
(Note 1)
(Voltage Referred to GND Pin)
Input Supply Voltage (Pin 6)
LTC1174 ........................................... –0.3V to 13.5V
LTC1174HV ...................................... – 0.3V to 18.5V
Switch Current (Pin 5) .............................................. 1A
Switch Voltage (Pin 5)
LTC1174 ................................................. VIN – 13.5V
LTC1174HV ............................................ V
UU
W
– 18.5V
IN
PACKAGE/ORDER I FOR ATIO
TOP VIEW
(VFB*)
V
OUT
1
LB
2
OUT
LB
3
IN
GND
4
N8 PACKAGE
8-LEAD PDIP
* ADJUSTABLE OUTPUT VERSION
T
= 125°C, θJA = 110°C/W
JMAX
SHUTDOWN
8
I
7
PGM
V
6
IN
SW
5
Operating Temperature Range
LTC1174CX ............................................ 0°C to 70°C
LTC1174IX ........................................ – 40°C to 85°C
Junction Temperature (Note 2)............................ 125°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
TOP VIEW
V
(VFB*)
OUT
1
LB
2
OUT
LB
3
IN
GND
4
S8 PACKAGE
8-LEAD PLASTIC SO
* ADJUSTABLE OUTPUT VERSION
T
= 125°C, θJA = 150°C/W
JMAX
SHUTDOWN
8
I
7
PGM
V
6
IN
SW
5
ORDER PART NUMBER
LTC1174CN8
LTC1174CN8-3.3
LTC1174CN8-5
LTC1174IN8
LTC1174HVCN8
LTC1174HVCN8-3.3
LTC1174HVCN8-5
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
temperature range, otherwise specifications are at T
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
V
V
∆V
FB
FB
OUT
Feedback Current LTC1174/LTC1174HV 1 µA
Feedback Voltage LTC1174/LTC1174HV
Regulated Output Voltage LTC1174-3.3/LTC1174HV-3.3
Output Voltage Line Regulation VIN = 6V to 12V, I
OUT
LTC1174-5/LTC1174V-5
The ● denotes specifications which apply over the full operating
= 25°C. VIN = 9V, V
A
= 100mA, I
LOAD
ORDER PART NUMBER
LTC1174CS8
LTC1174CS8-3.3
LTC1174CS8-5
LTC1174IS8
LTC1174HVCS8
LTC1174HVCS8-3.3
LTC1174HVCS8-5
LTC1174HVIS8
SHUTDOWN
PGM
= VIN, I
= VIN (Note 3) 10 70 mV
= 0V, unless otherwise noted.
PGM
●
●
●
S8 PART MARKING
1174
117433
117450
1174I
1174H
1174H3
1174H5
1174HI
1.20 1.25 1.30 V
3.14 3.30 3.46 V
4.75 5.00 5.25 V
1174fe
2
Page 3
LTC1174
LTC1174-3.3/LTC1174-5
ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at T
The ● denotes specifications which apply over the full operating
= 25°C. VIN = 9V, V
A
SHUTDOWN
= VIN, I
= 0V, unless otherwise noted.
PGM
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage Load Regulation LTC1174-3.3 (Note 3)
20mA < I
20mA < I
< 175mA, I
LOAD
< 400mA, I
LOAD
= 0V –5 –70 mV
PGM
PGM
= V
IN
–45 –70 mV
LTC1174-5 (Note 3)
20mA < I
20mA < I
I
Q
Input DC Supply Current (Note 4) Active Mode
LTC1174: 4V < V
LTC1174HV: 4V < V
< 175mA, I
LOAD
< 400mA, I
LOAD
IN
< 12V, I
< 16V, I
IN
= 0V –5 –70 mV
PGM
= V
PGM
IN
= 0V 450 600 µA
PGM
= 0V 450 600 µA
PGM
–50 –70 mV
Sleep Mode
LTC1174: 4V < V
LTC1174HV: 4V < V
< 12V 130 180 µA
IN
< 16V 130 180 µA
IN
SHUTDOWN (Note 4)
= 0V, 4V < VIN < 12V 1 10 µA
SHUTDOWN
= 0V, 4V < VIN < 16V 2 25 µA
= 0.4V 1.0 1.2 1.5 mA
= 0.4V 0.6 0.8 1.5 mA
LBOUT
OUT
= 0V
= 0V
●
0.54 0.60 0.83 A
●
0.27 0.34 0.53 A
●
●
0.75 1.30 Ω
0.90 1.55 Ω
= 12V 0.5 µA
SHUTDOWN
= 16V 2.0 µA
≤ 0.8V 0.5 µA
V
LBTRIP
I
LBIN
I
LBOUT
V
HYST
I
PEAK
R
ON
t
OFF
V
IH
V
IL
I
IH
I
IL
LTC1174: V
SHUTDOWN
LTC1174HV: V
Low-Battery Trip Point 1.25 1.4 V
Current into Pin 3 0.5 µA
Current Sunk by Pin 2 LTC1174: V
LBOUT
LTC1174HV: V
Comparator Hysteresis LTC1174/LTC1174HV 7.5 15 30 mV
Current Limit I
PGM
I
PGM
= VIN, V
= 0V, V
OUT
ON Resistance of Switch LTC1174
LTC1174HV
Switch Off-Time (Note 6) V
at Regulated Value 3 4 5 µs
OUT
SHUTDOWN Pin High Minimum Voltage at Pin 8 for Device to Be Active 1.2 V
SHUTDOWN Pin Low Maximum Voltage at Pin 8 for Device to Be in Shutdown 0.75 V
SHUTDOWN Pin Input Current LTC1174: V
SHUTDOWN
LTC1174HV: V
SHUTDOWN Pin Input Current 0 ≤ V
SHUTDOWN
The ● denotes specifications which apply over the full operating temperature range,
otherwise specifications are at – 40°C ≤ T
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
FB
I
LBOUT
I
PEAK
t
OFF
R
ON
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.
Feedback Voltage LTC1174I/LTC1174HVI
Current Sunk by Pin 2 V
Current Limit I
Switch Off-Time (Note 6) V
Switch On Resistance LTC1174I/LTC1174HVI
≤ 85°C. LTC1174I and LTC1174HVI Only.
A
= 0.4V (LTC1174I)
LBOUT
= 0.4V (LTC1174HVI)
V
LBOUT
= VIN, V
PGM
I
= 0V, V
PGM
I
= VIN, V
PGM
= 0V, V
I
PGM
at Regulated Value (LTC1174I)
OUT
V
at Regulated Value (LTC1174HVI)
OUT
= 0V (LTC1174I)
OUT
= 0V (LTC1174I) 0.34 A
OUT
= 0V (LTC1174HVI)
OUT
= 0V (LTC1174HVI) 0.34 A
OUT
Note 2: TJ is calculated from the ambient temperature TA and power
dissipation P
D
LTC1174CN8, LTC1174CN8-3.3, LTC1174CN8-5:
= TA + (PD × 110°C/W)
T
J
LTC1174CS8, LTC1174CS8-3.3, LTC1174CS8-5:
= TA + (PD × 150°C/W)
T
J
●
1.18 1.25 1.31 V
●
0.75 1.2 2.0 mA
●
0.50 0.8 1.6 mA
●
0.54 0.60 0.84 A
●
0.5 0.60 0.86 A
●
2.0 4 6.0 µs
●
1.8 4 6.2 µs
●
0.9 1.7 Ω
according to the following formulas:
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Page 4
LTC1174
LTC1174-3.3/LTC1174-5
ELECTRICAL CHARACTERISTICS
Note 3: Guaranteed by design.
Note 4: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 5: Current into Pin 6 only, measured without electrolytic input
capacitor.
Note 6: The off-time is wafer-sort trimmed.
UW
TYPICAL PERFOR A CE CHARACTERISTICS
Efficiency vs Load Current Efficiency vs Load Current Efficiency vs Load Current
100
95
90
85
EFFICIENCY (%)
80
75
70
1
100
VIN = 6V
= 9V
V
IN
L = 50µH
V
OUT
I
PGM
COIL = CTX50-4
10 100
LOAD CURRENT (mA)
= 5V
= 0V
1174 G01
200
100
95
90
85
EFFICIENCY (%)
80
75
70
1
100
VIN = 6V
VIN = 9V
L = 50µH
V
OUT
I
PGM
COIL = CTX50-4
10 100
LOAD CURRENT (mA)
= 5V
= V
IN
400
1174 G02
100
95
90
85
EFFICIENCY (%)
80
75
70
1
Efficiency vs Load CurrentEfficiency vs Load Current Efficiency vs Load Current
100
VIN = 6V
10 100
LOAD CURRENT (mA)
VIN = 9V
L = 100µH
= 5V
V
OUT
= V
I
PGM
IN
COIL = CTX100-4
1174 G03
500
90
80
70
EFFICIENCY (%)
60
50
1
VIN = 5V
VIN = 9V
10 100
LOAD CURRENT (mA)
L = 50µH
= 3.3V
V
OUT
= 0V
I
PGM
COIL = CTX50-4
1174 G04
300
90
80
70
EFFICIENCY (%)
60
50
1
VIN = 5V
VIN = 9V
L = 50µH
V
OUT
I
PGM
COIL = CTX50-4
10 100
LOAD CURRENT (mA)
= 3.3V
= V
IN
1174 G05
500
90
80
70
EFFICIENCY (%)
60
50
1
VIN = 5V
VIN = 9V
L = 100µH
V
OUT
I
PGM
COIL = CTX100-4
10 100
LOAD CURRENT (mA)
= 3.3V
= V
IN
500
1174 G06
4
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Page 5
LTC1174-3.3/LTC1174-5
INPUT VOLTAGE (V)
0
SUPPLY CURRENT (µA)
500
450
400
350
300
250
200
150
100
50
0
4
8
10
1174 G12
2
6
12
14
ACTIVE MODE
I
PGM
= V
IN
SLEEP MODE
I
PGM
= 0V
TA = 25°C
UW
TYPICAL PERFOR A CE CHARACTERISTICS
Switch Leakage Current
Line Regulation
6
I
LOAD
4
= 0V
I
PGM
2
0
–2
(mV)
–4
OUT
–6
∆V
–8
–10
–12
–14
0
2
= 100mA
4
INPUT VOLTAGE (V)
8
6
10
12
14
1174 G07
vs Temperature Efficiency vs Input Voltage
180
VIN = 13.5V
160
140
120
100
80
60
LEAKAGE CURRENT (nA)
40
20
0
20 60
0
40
TEMPERATURE (°C)
80
1174 G08
100
95
94
93
92
91
90
EFFICIENCY (%)
V
89
OUT
I
PGM
I
88
LOAD
CORE = CTX (Kool Mµ
87
5
68
L = 50µH
= 5V
= 0V
= 75mA
7
INPUT VOLTAGE (V)
LTC1174
L = 100µH
®
)
9
12
10 11 13
14
1174 G09
Efficiency vs Input Voltage
95
V
= 5V
OUT
94
93
92
I
EFFICIENCY (%)
91
90
89
68
5
= 300mA
LOAD
= V
I
PGM
7
INPUT VOLTAGE (V)
L = 100µH
COIL = CTX100-4
I
I
IN
10 14
9
LOAD
PGM
11
= 100mA
= 0V
12
13
1174 G10
Operating Frequency
vs V
– V
IN
OUT
2.0
V
= 5V
OUT
1.5
TA = 25°C
1.0
0.5
NORMALIZED FREQUENCY
0
0
2
1
(VIN – V
3
TA = 70°C
57
4
) VOLTAGE (V)
OUT
6
8
1174 G13
9
Supply Current in Shutdown
1.8
SHUTDOWN = 0V
1.6
= 25°C
T
A
CURRENT INTO PIN 6 ONLY
1.4
1.2
1.0
0.8
0.6
SUPPLY CURRENT (µA)
0.4
0.2
0
0
414
2
6
INPUT VOLTAGE (V)
Switch Resistance vs
Input Voltage
1.7
1.6
1.5
1.4
1.3
(Ω)
1.2
(ON)
1.1
RDS
1.0
0.9
0.8
0.7
4
LTC1174
6
8
INPUT VOLTAGE (V)
LTC1174HV
10
12
8
10 12
1174 G11
TA = 25°C
14 16 18 20
1174 G14
DC Supply Current
Off-Time vs Output Voltage
50
40
30
20
OFF-TIME (µs)
10
0
LTC1174-3.3
LTC1174HV-3.3
0
LTC1174-5
LTC1174HV-5
1
2
OUTPUT VOLTAGE (V)
3
4
5
1174 G15
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5
Page 6
LTC1174
LTC1174-3.3/LTC1174-5
U
UU
PI FU CTIO S
V
(VFB) (Pin 1): For the LTC1174, this pin connects to the
OUT
main voltage comparator’s input. On the LTC1174-3.3 and
LTC1174-5 this pin goes to an internal resistive divider
which sets the output voltage.
(Pin 2): Open Drain of an N-Channel Pull-Down. This
LB
OUT
pin will sink current when Pin 3 (LB
During shutdown the state of this pin is indeterminate.
LB
(Pin 3): The “–” Input of the Low-Battery Voltage
IN
Comparator. The “+” input is connected to a reference
voltage of 1.25V.
GND (Pin 4): Ground Pin.
U
U
FU CTIO AL DIAGRA
) goes below 1.25V.
IN
W
(Pin 1 connection shown for LTC1174-3.3 and LTC1174-5, changes create LTC1174)
SW (Pin 5): Drain of the P-Channel MOSFET Switch. Cathode
of Schottky diode must be closely connected to this pin.
V
(Pin 6): Input Supply Voltage. It must be decoupled
IN
close to ground Pin 4.
I
(Pin 7): Selects the Current Limit of the P-Channel
PGM
Switch. With I
with I
= 0V, the current trip value is reduced to 340mA.
PGM
= VIN, the current trip point is 600mA and
PGM
SHUTDOWN (Pin 8): Pulling this pin to ground keeps the
internal switch off and puts the LTC1174 in micropower
shutdown.
V
IN
6
gmV
V
LIM1
+
V
TH2
A5
–
SLEEP
+
A2
V
LIM2
I
PGM
7
R
SENSE
0.1Ω
–
–
A4
C
FB
LB
2
OUT
T
+
V
TH1
LB
IN
3
–
GND
A3
+
4
1.25V
REFERENCE
* R1 = 51k FOR LTC1174-3.3
R1 = 93.5k FOR LTC1174-5
RESET
SET
SHUTDOWN
8
Q
)
V
OUT (VFB
1
5
×
SW
R1*
V
FB
–
A1
31.5k
+
1174 BD
6
1174fe
Page 7
OPERATIO
LTC1174
LTC1174-3.3/LTC1174-5
U
(Refer to Functional Diagram)
The LTC1174 uses a constant off-time architecture to
switch its internal P-channel power MOSFET. The off-time
is set by an internal timing capacitor and the operating
frequency is a function of VIN.
The output voltage is set by an internal resistive divider
(LTC1174-3.3 and LTC1174-5) or an external divider returned to VFB Pin 1 (LTC1174). A voltage comparator A1
compares the divided output voltage to a reference voltage
of 1.25V.
To optimize efficiency, the LTC1174 automatically switches
®
between continuous and Burst Mode
operation. The voltage comparator is the primary control element when the
device is in Burst Mode operation, while the current comparator controls the output voltage in continuous mode.
During the switch“ON” time, switch current flows through
the 0.1Ω sense resistor. When this current reaches the
threshold of the current comparator A2, its output signal will
change state, setting the flip-flop and turning the switch off.
The timing capacitor, C
voltage goes below V
, begins to discharge until its
T
. Comparator A4 will then trip,
TH1
which resets the flip-flop and causes the switch to turn on
again. Also, the timing capacitor is recharged. The inductor
current will again ramp up until the current comparator A2
trips. The cycle then repeats.
When the load is relatively light, the LTC1174 automatically
goes into Burst Mode operation. The current mode loop is
interrupted when the output voltage reaches the desired
regulated value. The hysteretic voltage comparator A1 trips
when V
is above the desired output voltage, shutting off
OUT
the switch and causing the timing capacitor to discharge.
This capacitor discharges past V
below V
. Comparator A5 then trips and a sleep signal is
TH2
until its voltage drops
TH1
generated.
In sleep mode, the LTC1174 is in standby and the load
current is supplied by the output capacitor. All unused
circuitry is shut off, reducing quiescent current from
0.45mA to 0.13mA. When the output capacitor discharges
by the amount of the hysteresis of the comparator A1, the
P-channel switch turns on again and the process repeats
itself.
Operating Frequency and Inductor
Since the LTC1174 utilizes a constant off-time architecture,
its operating frequency is dependent on the value of V
IN
. The
frequency of operation can be expressed as:
f
=
where t
⎛
1
IN OUT
⎜
VV
⎝
t
OFF
OFF
IN D
= 4µs and VD is the voltage drop across the diode.
⎞
Hz
()
⎟
+
⎠
VV
−
Note that the operating frequency is a function of the input
and ouput voltage.
Although the size of the inductor does not affect the frequency, it does affect the ripple current. The peak-to-peak
ripple current is given by:
VV
I
RIPPLE
⎛
−
=
410
6
•
⎜
⎝
+
OUT D
L
⎞
A
()
⎟
⎠
−
PP
By choosing a smaller inductor, a low ESR output filter
capacitor has to be used (see C
and C
IN
). Moreover, core
OUT
loss will also increase (see Inductor Core Selection section)
due to higher ripple current.
Burst Mode is a registered trademark of Linear Technology Corporation.
1174fe
7
Page 8
LTC1174
I
I
A
mA
RMS
PEAK
RMS
≈
()
=2170
or 300mA
LTC1174-3.3/LTC1174-5
WUUU
APPLICATIO S I FOR ATIO
Inductor Core Selection
With the value of L selected, the type of inductor must be
chosen. Basically there are two kinds of losses in an
inductor, core and copper
Core losses are dependent on the peak-to-peak ripple
current and the core material. However it is independent of
the physical size of the core. By increasing the inductance
the inductor’s peak-to-peak ripple current will decrease,
therefore reducing core loss. Utilizing low core loss material, such as molypermalloy or Kool Mµ will allow users to
concentrate on reducing copper loss and preventing saturation. Figure 1 shows the effect of different core material on
the efficiency of the LTC1174. The CTX core is Kool Mµ and
the CTXP core is powdered iron (material 52).
Although higher inductance reduces core loss, it increases
copper loss as it requires more windings. When space is not
100
90
80
70
EFFICIENCY (%)
60
50
1
CTX100-4
CTX100-4P
VIN = 5V
= 3.3V
V
OUT
= V
I
PGM
10 100 500
LOAD CURRENT (mA)
IN
a premium larger gauge wire can be used to reduce the wire
resistance. This also prevents excessive heat dissipation.
C
IN
In continuous mode the source current of the P-channel
MOSFET is a square wave of duty cycle V
OUT/VIN
. To prevent
large voltage transients, a low ESR input capacitor sized for
the maximum RMS current must be used. The C
RMS
IN
current is given by:
12/
A
()
RMS
, where I
OUT
RMS
=
I
RMS
IVVV
[]
OUT OUT IN OUT
≈
−
()
V
IN
This formula has a maximum at VIN = 2V
I
/ 2. This simple worst case is commonly used for design
OUT
because even significant deviations do not offer much relief.
Note that ripple current directly affects capacitor’s lifetime.
DO NOT UNDERSPECIFY THIS COMPONENT. An additional
0.1µF ceramic capacitor is also required on VIN for high
frequency decoupling.
C
OUT
To avoid overheating, the output capacitor must be sized to
handle the ripple current generated by the inductor. The
worst case RMS ripple current in the output capacitor is
given by:
100
90
80
70
EFFICIENCY (%)
60
50
Figure 1. Efficiency Using Different Types of
Inductor Core Material
8
CTX50-4
CTX50-4P
hysteresis of the voltage comparator, ESR of the output
capacitor is also a concern. Too high of an ESR will create
a higher ripple output voltage and at the same time cause the
LTC1174 to sleep less often. This will affect the efficiency of
the LTC1174. For a given technology, ESR is a direct
Although the output voltage ripple is determined by the
VIN = 5V
= 3.3V
V
OUT
= V
I
PGM
IN
1
10 100 500
LOAD CURRENT (mA)
1174 F01
function of the volume of the capacitor. Several small-sized
capacitors can also be paralleled to obtain the same ESR as
one large can. Manufacturers such as Nichicon, Chemicon
and Sprague should be considered for high performance
capacitors. The OS-CON semiconductor dielectric capacitor available from Sanyo has the lowest ESR for its size, at
a higher price.
1174fe
Page 9
WUUU
V
R
R
LBTRIP
=+
⎛
⎝
⎜
⎞
⎠
⎟
125 1
4
3
.
LTC1174
–
+
1.25V
REFERENCE
R4
R3
3
V
IN
1174 F03
APPLICATIO S I FOR ATIO
LTC1174
LTC1174-3.3/LTC1174-5
Catch Diode Selection
The catch diode carries load current during the off-time. The
average diode current is therefore dependent on the
P-channel switch duty cycle. At high input voltages the
diode conducts most of the time. As V
approaches V
IN
OUT
the diode conducts only a small fraction of the time. The
most stressful condition for the diode is when the output is
short-circuited. Under this condition the diode must safely
handle I
at close to 100% duty cycle. A fast switching diode
PEAK
must also be used to optimize efficiency. Schottky diodes are
a good choice for low forward drop and fast switching times.
Most LTC1174 circuits will be well served by either a 1N5818,
a MBRS140T3 or a MBR0520L Schottky diode.
Short-Circuit Protection
The LTC1174 is protected from output short by its internal
current limit. Depending on the condition of I
PGM
pin, the
limit is either set to 340mA or 600mA. In addition, the offtime of the switch is increased to allow the inductor’s
current to decay far enough to prevent any current build-up
(see Figure 2).
I
= V
PGM
IN
compared with a 1.25V reference voltage. With the current
going into Pin 3 being negligible, the following expression
is used for setting the trip limit:
When the LTC1174 is shut down, the low-battery detector
is inactive.
Figure 3. Low-Battery Comparator
LTC1174 Adjustable/Low Noise Applications
The LTC1174 develops a 1.25V reference voltage between
the feedback (Pin 1) terminal and ground (see Figure 4). 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:
I
= 0
PGM
GND
L = 100µH
= 13.5V
V
IN
Figure 2. Inductor's Current with Output Shorted
20µs/DIV
1174 F02
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 3) which is
V
=+
1251
OUT
.
⎛
⎜
⎝
⎞
⎟
⎠
1
R
2
R
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 LTC1174. Alternatively, a
capacitor across R2 can be used to increase the switching
frequency for low noise operation.
Inverting Applications
The LTC1174 can easily be set up for a negative output
voltage. If –5V is desired, the LTC1174-5 is ideal for this
application as it requires the least components. Figure 5
shows the schematic for this application. Note that the
1174fe
9
Page 10
LTC1174
LTC1174-3.3/LTC1174-5
WUUU
APPLICATIO S I FOR ATIO
V
OUT
6.8nF**
LTC1174 V
ADJUSTABLE APPLICATIONS
*
LOW NOISE APPLICATIONS
**
1
FB
100pF*
Figure 4. LTC1174 Adjustable Configuration
INPUT VOLTAGE
4V TO 12V
V
LB
IN
LB
OUT
I
PGM
LTC1174HV-5
IN
SHUTDOWN
GND
3
2
7
AVX TPSD476K016
*
COILTRONICS CTX50-4
**
6
8
1
V
OUT
5
SW
4
0.1µF
50µH**
MBRS140T3
Figure 5. Positive-to-Negative 5V Converter
output voltage is now taken off the GND pin. Therefore,
the maximum input voltage is now determined by the
difference between the absolute maximum voltage rating
and the output voltage. A maximum of 12V is specified in
Figure 5, giving the circuit a 1.5V of headroom for VIN. Note
that the circuit can operate from a minimum of 4V, making
it ideal for a 4 NiCad cell application. For a higher output
current circuit, please refer to the Typical Applications
section.
R2
R1
1174 F04
47µF*
+
16V
×2
+
47µF*
16V
×2
V
OUT
–5V
45mA
1174 F05
LTC1174-5 regulator and also to one or more loads in
parallel with the the regulator’s V
. If the battery is dis-
IN
connected while the LTC1174/LTC1174-3.3/LTC1174-5
regulator is supplying a light load and one of the parallel
circuits is a heavy load, the input capacitor of the LTC1174/
LTC1174-3.3/LTC1174-5 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 V
is reapplied. Bat-
IN
tery 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.
Prevention against latchup can be accomplished by simply connecting a Schottky diode across the SW and V
IN
pins as shown in Figure 6. The diode will normally be
reverse biased unless V
time the diode will clamp the (V
is pulled below V
IN
– VIN) potential to less
OUT
at which
OUT
than the 0.6V required for latchup. Note that a low leakage
Schottky should be used to minimize the effect 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 V
and ground with a value low
OUT
enough to sink the maximum possible leakage current.
LATCHUP
PROTECTION
SCHOTTKY
Absolute Maximum Ratings and Latchup Prevention
The absolute maximum ratings specify that SW (Pin 5) can
never exceed V
(Pin 6) by more than 0.3V. Normally this
IN
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 LTC1174/LTC1174-3.3/
10
V
IN
LTC1174
LTC1174-3.3
LTC1174-5
SW
V
OUT
+
1174 F06
Figure 6. Preventing Absolute Maximum
Ratings from Being Exceeded
1174fe
Page 11
WUUU
INDUCTOR CURRENT
TIME
I
PEAK
I
V
AVG CURRENT
= I
OUT
=
= 350mA
I
PEAK
+ I
V
2
1174 F08
APPLICATIO S I FOR ATIO
LTC1174
LTC1174-3.3/LTC1174-5
Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC1174. These items are also illustrated graphically in
the layout diagram in Figure 7. Check the following in your
layout:
1. Is the Schottky catch diode
closely
connected between
ground (Pin 4) and switch (Pin 5)?
2. Is the “+” plate of C
closely
IN
connected to VIN (Pin 6)?
This capacitor provides the AC current to the internal
P-channel MOSFET.
3. Is the 0.1µF V
decoupling capacitor
IN
closely
conected
between VIN (Pin 6) and ground (Pin 4)? This capacitor
carries the high frequency peak currents.
4. Is the SHUTDOWN (Pin 8) actively pulled to V
during
IN
normal operation? The SHUTDOWN pin is high impedance and must not be allowed to float.
5. Is the I
I
PGM
(Pin 7) pulled either to VIN or ground? The
PGM
pin is high impedance and must not be allowed
to float.
DESIGN EXAMPLE
As a design example, assume V
5V, and I
for this application, with I
= 350mA maximum. The LTC1174-5 is used
OUT
PGM
= 9V (nominal), V
IN
OUT
=
(Pin 7) connected to VIN. The
minmum value of L is determined by assuming the
LTC1174-5 is operating in continuous mode.
Figure 8. Continuous Inductor Current
With I
0.1A.The peak-to-peak ripple inductor current, I
= 350mA and I
OUT
PEAK
= 0.6A (I
= VIN), IV =
PGM
RIPPLE
, is
0.5A and is also equal to:
VV
I
RIPPLE
⎛
−
=
410
6
•
⎜
⎝
+
OUT D
L
⎞
A
()
⎟
⎠
−
PP
OUTPUT DIVIDER
REQUIRED WITH
ADJUSTABLE
VERSION ONLY
Figure 7. LTC1174 Layout Diagram (See Board Layout Checklist)
R2
I
PGM
V
SW
8
7
6
IN
54
0.1µF
D
+
C
IN
C
OUT
V
IN
L
+
V
OUT
1174 F07
1174fe
1
V
OUT
SHUTDOWN
(VFB)
2
LB
OUT
3
R1
LB
IN
LTC1174
GND
BOLD LINES INDICATE
HIGH CURRENT PATH
11
Page 12
LTC1174
LTC1174-3.3/LTC1174-5
WUUU
APPLICATIO S I FOR ATIO
Solving for L in the above equation and with VD = 0.6V,
L = 44.8µH. The next higher standard value of L is 50µH
(example: Coiltronics CTX50-4). The operating frequency,
neglecting voltage across diode V
V
.•
kHz
5
⎜
⎝
f
≈−
2 5 10 1
=
111
⎛
OUT
V
IN
⎞
⎟
⎠
With the value of L determined, the requirements for C
and C
are calculated. For CIN, its RMS current rating
OUT
D
is:
IN
should be at least:
/
A
()
RMS
I
RMS
For C
I
RMS
IVVV
[]
OUT OUT IN OUT
=
mA
=12174
, the RMS current rating should be at least:
OUT
I
PEAK
≈
=2300
mA
−
()
V
IN
A
()
RMS
Now allow VIN to drop to 6V. At this minimum input voltage
the operating frequency will decrease. The new frequency
is 42kHz.
Table 1. Inductor Manufacturers
MANUFACTURER PART NUMBER
Coilcraft DT3316 Series
1102 Silver Lake Road
Cary, IL 60013
(708) 639-2361
Coiltronics Inc. Econo-Pac
6000 Park of Commerce Blvd. Octa-Pac
Boca Raton, FL 33487
(407) 241-7876
Gowanda Electronics Corporation GA10 Series
1 Industrial Place
Gowanda, NY 14070
(716) 532-2234
Sumida Electric Co. Ltd. CD 54 Series
637 E. Golf Road, Suite 209 CD 75 Series
Arlington Heights, IL 60005
(708) 956-0666/7
Table 2. Capacitor Manufacturers
MANUFACTURER PART NUMBER
AVX Corporation TPS Series
P.O. Box 887 TAJ Series
Myrtle Beach, SC 29578
(803) 448-9411
Nichicon America Corporation PL Series
927 East State Parkway
Schaberg, IL 60173
(708) 843-7500
Sanyo Video Components OS-CON Series
2001 Sanyo Avenue
San Diego, CA 92173
(619) 661-6385
Attn: Sales Dept.
12
1174fe
Page 13
TYPICAL APPLICATIO S
6V to 5V Step-Down Regulator with Low-Battery Detection
LOW-BATTERY INDICATOR
*
IS SET TO TRIP AT V
AVX TPSD476K016
**
= MBRS140T3 (SURFACE MOUNT)
D1
1N5818
†
L1 SELECTION
MANUFACTURER
COILTRONICS
SUMIDA
GOWANDA
= 5.5V
IN
PART NO.
CTX100-4
CD75-101
GA10-103K
TYPE
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
U
BATTERY
INDICATOR
162k
47.5k
*LOW-
4.7k
LTC1174
LTC1174-3.3/LTC1174-5
INPUT VOLTAGE
6V
+
1174 TA03
47µF**
16V
×2
+
47µF**
16V
×2
6
V
I
LB
LB
PGM
IN
SHUTDOWN
OUT
LTC1174-5
IN
GND
4
7
2
3
8
1
V
OUT
5
SW
0.1µF
†
L1
100µH
D1
V
OUT
5V
365mA
INPUT VOLTAGE
4V TO 12.5V
AVX TPSD226K025
*
AVX TPSD476K016
**
†
COILTRONICS CTX50-4
High Efficiency 3.3V Regulator
+
22µF*
25V
×3
50µH
1N5818
7
3
2
I
PGM
LB
IN
LTC1174-3.3
LB
OUT
6
V
IN
SHUTDOWN
V
GND
4
OUT
SW
8
1
5
†
+
1174 TA04
0.1µF
47µF**
16V
×2
V
OUT
3.3V
425mA
1174fe
13
Page 14
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO S
INPUT VOLTAGE
4V TO 12.5V
7
I
PGM
3
LB
2
LB
AVX TPSD226K025
*
AVX TPSD105K010
**
†
COILTRONICS CTX50-4
Low Noise 3V Regulator
6
V
IN
SHUTDOWN
IN
LTC1174
OUT
GND
4
V
SW
8
1
FB
5
+
50µH
1N5818
22µF*
25V
×3
†
0.1µF
6.8nF
100µF**
+
10V
×2
1174 TA05
42k
30k
V
OUT
3V
450mA
*
LOW-BATTERY INDICATOR
IS SET TO TRIP AT V
**
AVX TPSD106K035
***
AVX TPSD105K010
D1
= MBRS130LT3 (SURFACE MOUNT)
1N5818
†
L1 SELECTION
MANUFACTURER
COILTRONICS
COILCRAFT
SUMIDA
GOWANDA
= 4.4V
IN
PART NO.
CTX50-3
DT3316-473
CD54-470
GA10-472K
VIN(V)
I
OUT MAX
4
110
6
140
8
10
12.5
TYPE
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
170
200
235
Positive-to-Negative (–5V) Converter
INPUT VOLTAGE
4V TO 12.5V
(mA)
4.7K
BATTERY
INDICATOR
280k
43k
*LOW-
7
2
3
I
PGM
LB
OUT
LTC1174HV-5
LB
IN
6
V
IN
SHUTDOWN
V
GND
4
OUT
SW
+
10µF**
+
35V
×2
100µF***
10V
1174 TA06
V
OUT
–5V
0.1µF
8
1
5
†
L1
50µH
D1
14
1174fe
Page 15
TYPICAL APPLICATIO S
LOW-BATTERY INDICATOR
*
IS SET TO TRIP AT V
AVX TPSD336K020
**
AVX TPSD105K010
***
= MBRS140T3 (SURFACE MOUNT)
D1
1N5818
†
L1 SELECTION
MANUFACTURER
COILTRONICS
COILCRAFT
SUMIDA
GOWANDA
= 4.4V
IN
PART NO.
CTX50-3
DT3316-473
CD54-470
GA10-472K
I
VIN(V)
OUT MAX
4
5
6
7
TYPE
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
U
Positive-to-Negative (– 3.3V) Converter
175
205
230
255
(mA)
*LOW-
BATTERY
INDICATOR
220k
43k
4.7K
7
2
3
LTC1174
LTC1174-3.3/LTC1174-5
INPUT VOLTAGE
4V TO 13.5V
+
+
33µF**
20V
×2
100µF***
10V
×2
1174 TA07
V
I
SHUTDOWN
PGM
LB
OUT
LTC1174HV-3.3
LB
IN
GND
6
IN
4
8
1
V
OUT
5
SW
0.1µF
†
L1
50µH
D1
V
OUT
–3.3V
210mA
AVX TPSD336K020
*
= MBRS140T3 (SURFACE MOUNT)
D1
1N5818
†
L1 SELECTION
MANUFACTURER
COILTRONICS
COILCRAFT
SUMIDA
GOWANDA
PART NO.
CTX50-3
DT3316-473
CD54-470
GA10-472K
TYPE
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
Negative Boost Converter
7
I
PGM
2
LB
OUT
3
33µF*
+
16V
×2
LB
V
SHUTDOWN
LTC1174-3.3
IN
GND
6
IN
4
8
1
V
OUT
5
SW
D1
INPUT VOLTAGE
–5V
†
L1
50µH
310k
50k
0.1µF
0.1µF
+
1174 TA08
33µF*
20V
×2
V
–9V
175mA
OUT
1174fe
15
Page 16
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO S
INPUT
VOLTAGE
6V TO 12.5V
SANYO OS-CON
*
AVX TPSD476K016
**
= MBRS140T3 (SURFACE MOUNT)
D1
†
L1 SELECTION
MANUFACTURER
COILTRONICS
COILCRAFT
SUMIDA
GOWANDA
††
USE 1% METAL FILM RESISTORS
1N5818
PART NO.
CTX50-3
DT3316-473
CD54-470
GA10-472K
TYPE
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
3
LB
IN
2
LB
OUT
7
I
PGM
9V to 5V Pre-Post Regulator
D1
L1
50µH
+
†
+
6
V
IN
SHUTDOWN
LTC1174
GND
4
V
SW
8
1
FB
5
100µF*
16V
47µF**
16V, ×2
100pF
0.1µF
110k
30.1k
V
8
V
OUT
0.1µF
IN
LT®1121-5
5
SHUTDOWN
GND
3
1174 TA09
††
††
1
+
OUT
5V
150mA
1µF
SOLID
TANTALUM
VIN(V)
4
5
6
7
8
9
10
11
12
AVX TAJE106K050
*
AVX TPSD476K016
**
= MBRS140T3 (SURFACE MOUNT)
D1
1N5818
†
L1 SELECTION
MANUFACTURER
COILTRONICS
COILCRAFT
SUMIDA
GOWANDA
††
USE 1% METAL FILM RESISTORS
I
OUT MAX
(mA)
20
25
30
35
43
50
55
60
65
PART NO.
CTX100-3
DT3316-104
CD75-101
GA10-103K
VOLTAGE
4V TO 12.5V
TYPE
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
INPUT
LCD Display Power Supply
††
1174 TA10
56.2k
50k
998k
+
††
††
10µF*
50V
×4
V
OUT
–24V
50mA AT
= 9V
V
IN
6
V
LB
I
LB
PGM
IN
OUT
IN
SHUTDOWN
LTC1174
GND
4
3
7
2
+
47µF**
16V
×2
0.1µF
V
SW
8
1
FB
5
1N914
0.1µF
2N2222
2N5210
Si9435
D1
†
L1
100µH
16
1174fe
Page 17
TYPICAL APPLICATIO S
SANYO OS-CON
*
WIMA MKS2
**
†
COILTRONICS CTX100-4
(V)
L1B
V
IN
4
6
8
10
12
13
CTX100-4
I
OUT MAX
4
(mA)
75
100
125
145
160
180
23
L1A
1
U
INPUT VOLTAGE
7
I
PGM
3
LB
IN
LTC1174HV-5
2
LB
OUT
4V TO 12.5V
6
V
IN
SHUTDOWN
GND
4
9V to 5V, –5V Outputs
8
1
V
OUT
5
SW
MBRS140T3
LTC1174
LTC1174-3.3/LTC1174-5
+
†
L1B
100µH
3.3µF**
+
0.1µF0.1µF
L1A
100µH
MBRS140T3
100µF*
16V
†
+
1174 TA11
100µF*
20V
V
OUT
5V
135mA AT
= 9V
V
IN
100µF*
16V
–V
OUT
–5V
135mA AT
= 9V
V
IN
AVX TAJD226K035
*
WIMA MKS2
**
†
COILTRONICS CTX100-4
††
USE 1% METAL FILM RESISTORS
(V)
V
IN
4
5
6
7
8
9
10
11
12
I
OUT MAX
(mA)
20
25
35
45
50
55
62
67
73
INPUT VOLTAGE
4V TO 12.5V
7
I
PGM
3
LB
IN
2
LB
OUT
6
V
IN
SHUTDOWN
LTC1174
GND
4
9V to 12V, –12V Outputs
0.1µF
8
1
V
FB
SW
Si9430DY
5
1N914
+
22µF*
35V
×3
3.3µF**
4
L1B
100µH
3
MBRS140T3
†
1
MBRS140T3
+
L1A
100µH
22µF*
35V
×2
L1B
23
CTX100-4
4
†
2
+
22µF*
35V
×2
L1A
1
V
OUT
12V
55mA AT
††
301k
34k
††
1174 TA12
= 9V
V
IN
–V
OUT
–12V
55mA AT
= 9V
V
IN
1174fe
17
Page 18
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO S
INPUT
VOLTAGE
6V TO 12.5V
+
100µF*
20V
SANYO OS-CON CAPACITOR
*
†
COILTRONICS CTX50-4
TPO610L
0.1µF
100k
Automatic Current Selection
OUT
LTC1174-5
IN
6
V
IN
SHUTDOWN
V
GND
4
OUT
SW
8
1
5
100k
2
LB
7
I
PGM
3
LB
50µH
1N5818
100k
36.5k
V
OUT
5V
0mA TO
320mA
1174 TA13
†
+
100µF*
16V
SANYO OS-CON
*
WIMA MKS2
**
†
COILTRONICS CTX100-4
L1B
CTX100-4
4
Buck-Boost Converter
INPUT VOLTAGE
4V TO 12V
6
V
PGM
IN
LTC1174HV-5
OUT
IN
SHUTDOWN
GND
4
7
I
3
LB
2
LB
23
L1A
1
8
1
V
OUT
SW
5
4
3
†
L2A
100µH
3.3µF**
0.1µF
+
100µF*
20V
V
OUT
1
L1A
100µH
1N5818
†
2
1174 TA14
5V
160mA
+
100µF*
16V
18
1174fe
Page 19
PACKAGE DESCRIPTIO
.300 – .325
(7.620 – 8.255)
U
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
.045 – .065
(1.143 – 1.651)
LTC1174
LTC1174-3.3/LTC1174-5
.400*
(10.160)
.130 ± .005
(3.302 ± 0.127)
MAX
87 6
5
.065
(1.651)
.008 – .015
(0.203 – 0.381)
+.035
.325
–.015
+0.889
8.255
()
–0.381
NOTE:
1. DIMENSIONS ARE
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
INCHES
MILLIMETERS
TYP
.100
(2.54)
BSC
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.050 BSC
.245
MIN
.045 ±.005
.160 ±.005
.018 ± .003
(0.457 ± 0.076)
S8 Package
.228 – .244
(5.791 – 6.197)
.120
(3.048)
MIN
8
.020
(0.508)
MIN
.189 – .197
(4.801 – 5.004)
NOTE 3
7
6
.255 ± .015*
(6.477 ± 0.381)
5
.150 – .157
(3.810 – 3.988)
NOTE 3
12
4
3
N8 1002
.030 ±.005
TYP
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
(0.254 – 0.508)
.008 – .010
(0.203 – 0.254)
NOTE:
1. DIMENSIONS IN
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
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.
× 45°
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
INCHES
(MILLIMETERS)
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
1
3
2
4
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
SO8 0303
1174fe
19
Page 20
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO
Battery Charger
INPUT VOLTAGE
8V TO 12.5V
*
AVX TAJD226K020
**
AVX TAJD107K010
D1,D2
= MBRS140T3
(SURFACE MOUNT)
1N5818
†
L1 SELECTION
MANUFACTURER
COILTRONICS
COILCRAFT
SUMIDA
GOWANDA
PART NO.
CTX50-2P
DT3316-473
CD54-470
GA10-472K
VIN(V)
8
9
10
11
12
TYPE
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
I
OUT MAX
320
325
330
335
335
(mA)
+
6
V
PGM
IN
SHUTDOWN
IN
LTC1174
OUT
GND
4
7
I
3
LB
2
LB
V
SW
8
1
FB
5
D1
L1
50µH
0.1µF
†
150k
33k
22µF*
20V
×2
+
1174 TA15
D2
100µF**
10V
V
4 NiCAD BATTERY
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
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LTC1574 High Efficiency Step-Down DC/DC Regulator LTC1174 with Internal Schottky Diode
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LTC1701 1MHz Step-Down DC/DC Converter in SOT-23 VIN = 2.5V to 5.5V, IQ = 135µA, V
LTC1707 High Efficiency Synchronous Step-Down Regulator VIN = 2.85 to 8.5V, Selectable Burst Mode Operation,
600mA Output Current, SO-8 Package
LTC1877 High Efficiency Synchronous Step-Down Regulator 600mA at VIN = 5V, 2.65V to 10V = VIN, IQ = 10µA
Output Ripple, SOT-23 Package
P-P
= 5V to 1.25V
OUT
OUT
TO
20
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
1174fe
LT 1006 REV E • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 1994
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