LTC1174
LTC1174-3.3/LTC1174-5
High Efficiency
Step-Down and Inverting
DC/DC Converter
FEATURES
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DESCRIPTIO
High Efficiency: Up to 94%
Peak Inductor Current Independent of
Inductor Value
Short-Circuit Protection
Optimized for 5V to – 5V Applications
Wide V
IN
Range: 4V to 18.5V
Low Dropout Operation
Low-Battery Detector
Pin Selectable Current Limit
Internal 0.9Ω Power Switch: V
IN
= 9V
Only Four External Components Required
130µA Standby Current
Active Low Micropower Shutdown
The LTC
®
1174 is a simple current mode DC/DC converter
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 continu-
ously 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 ultra-
high 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.
APPLICATIO S
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Distributed Power Systems
Step-Down Converters
Inverting Converters
Memory Backup Supply
Portable Instruments
Battery-Powered Equipment
TYPICAL APPLICATIO
V
IN
9V
3
2
7
High Efficiency Step-Down Converter
100
LTC1174-5 Efficiency
6
V
IN
LB
IN
LB
OUT
I
PGM
LTC1174-5
GND
4
SHUTDOWN
V
OUT
SW
8
1
5
100µH
1N5818
†
+
EFFICIENCY (%)
15µF*
25V
×3
95
V
IN
= 6V
90
85
80
75
L = 100µH
V
OUT
= 5V
I
PGM
= 0V
1
10
LOAD CURRENT (mA)
100 200
1174 TA02
5V
175mA
+
100µF**
10V
1174 TA01
* (3) AVX TPSD156K025
** AVX TPSD107K010
†
COILTRONICS CTX100-4
70
U
V
IN
= 9V
1174fe
U
U
1
LTC1174
LTC1174-3.3/LTC1174-5
ABSOLUTE
AXI U
RATI GS
(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 ................................................. V
IN
– 13.5V
LTC1174HV ............................................ V
IN
– 18.5V
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
OUT
(V
FB
*) 1
LB
OUT
2
LB
IN
3
GND 4
N8 PACKAGE
8-LEAD PDIP
* ADJUSTABLE OUTPUT VERSION
T
JMAX
= 125°C,
θ
JA
= 110°C/W
8
7
6
5
SHUTDOWN
I
PGM
V
IN
SW
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
SYMBOL
I
FB
V
FB
V
OUT
∆V
OUT
PARAMETER
Feedback Current
Feedback Voltage
Regulated Output Voltage
Output Voltage Line Regulation
The
●
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 9V, V
SHUTDOWN
= V
IN
, I
PGM
= 0V, unless otherwise noted.
CONDITIONS
LTC1174/LTC1174HV
LTC1174/LTC1174HV
LTC1174-3.3/LTC1174HV-3.3
LTC1174-5/LTC1174V-5
V
IN
= 6V to 12V, I
LOAD
= 100mA, I
PGM
= V
IN
(Note 3)
MIN
●
●
●
2
U
U
W
W W
U
W
(Note 1)
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
OUT
(V
FB
*) 1
LB
OUT
2
LB
IN
3
GND 4
8
7
6
5
SHUTDOWN
I
PGM
V
IN
SW
S8 PACKAGE
8-LEAD PLASTIC SO
* ADJUSTABLE OUTPUT VERSION
T
JMAX
= 125°C,
θ
JA
= 150°C/W
ORDER PART NUMBER
LTC1174CS8
LTC1174CS8-3.3
LTC1174CS8-5
LTC1174IS8
LTC1174HVCS8
LTC1174HVCS8-3.3
LTC1174HVCS8-5
LTC1174HVIS8
S8 PART MARKING
1174
117433
117450
1174I
1174H
1174H3
1174H5
1174HI
TYP
1.25
3.30
5.00
10
1.20
3.14
4.75
MAX
1
1.30
3.46
5.25
70
UNITS
µA
V
V
V
mV
1174fe
LTC1174
LTC1174-3.3/LTC1174-5
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
Output Voltage Load Regulation
The
●
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 9V, V
SHUTDOWN
= V
IN
, I
PGM
= 0V, unless otherwise noted.
CONDITIONS
LTC1174-3.3 (Note 3)
20mA < I
LOAD
< 175mA, I
PGM
= 0V
20mA < I
LOAD
< 400mA, I
PGM
= V
IN
LTC1174-5 (Note 3)
20mA < I
LOAD
< 175mA, I
PGM
= 0V
20mA < I
LOAD
< 400mA, I
PGM
= V
IN
Active Mode
LTC1174: 4V < V
IN
< 12V, I
PGM
= 0V
LTC1174HV: 4V < V
IN
< 16V, I
PGM
= 0V
Sleep Mode
LTC1174: 4V < V
IN
< 12V
LTC1174HV: 4V < V
IN
< 16V
SHUTDOWN (Note 4)
LTC1174: V
SHUTDOWN
= 0V, 4V < V
IN
< 12V
LTC1174HV: V
SHUTDOWN
= 0V, 4V < V
IN
< 16V
MIN
TYP
–5
–45
–5
–50
450
450
130
130
1
2
1.25
1.0
0.6
7.5
0.54
0.27
1.2
0.8
15
0.60
0.34
0.75
0.90
4
MAX
–70
–70
–70
–70
600
600
180
180
10
25
1.4
0.5
1.5
1.5
30
0.83
0.53
1.30
1.55
5
0.75
0.5
2.0
0.5
UNITS
mV
mV
mV
mV
µA
µA
µA
µA
µA
µA
V
µA
mA
mA
mV
A
A
Ω
Ω
µs
V
V
µA
µA
µA
I
Q
Input DC Supply Current (Note 4)
V
LBTRIP
I
LBIN
I
LBOUT
V
HYST
I
PEAK
R
ON
t
OFF
V
IH
V
IL
I
IH
I
IL
Low-Battery Trip Point
Current into Pin 3
Current Sunk by Pin 2
Comparator Hysteresis
Current Limit
ON Resistance of Switch
Switch Off-Time (Note 6)
SHUTDOWN Pin High
SHUTDOWN Pin Low
SHUTDOWN Pin Input Current
SHUTDOWN Pin Input Current
LTC1174: V
LBOUT
= 0.4V
LTC1174HV: V
LBOUT
= 0.4V
LTC1174/LTC1174HV
I
PGM
= V
IN
, V
OUT
= 0V
I
PGM
= 0V, V
OUT
= 0V
LTC1174
LTC1174HV
V
OUT
at Regulated Value
Minimum Voltage at Pin 8 for Device to Be Active
Maximum Voltage at Pin 8 for Device to Be in Shutdown
LTC1174: V
SHUTDOWN
= 12V
LTC1174HV: V
SHUTDOWN
= 16V
0
≤
V
SHUTDOWN
≤
0.8V
●
●
●
●
3
1.2
The
●
denotes specifications which apply over the full operating temperature range,
otherwise specifications are at – 40°C
≤
T
A
≤
85°C. LTC1174I and LTC1174HVI Only.
SYMBOL PARAMETER
V
FB
Feedback Voltage
I
LBOUT
Current Sunk by Pin 2
I
PEAK
Current Limit
CONDITIONS
LTC1174I/LTC1174HVI
V
LBOUT
= 0.4V (LTC1174I)
V
LBOUT
= 0.4V (LTC1174HVI)
I
PGM
= V
IN
, V
OUT
= 0V (LTC1174I)
I
PGM
= 0V, V
OUT
= 0V (LTC1174I)
I
PGM
= V
IN
, V
OUT
= 0V (LTC1174HVI)
I
PGM
= 0V, V
OUT
= 0V (LTC1174HVI)
V
OUT
at Regulated Value (LTC1174I)
V
OUT
at Regulated Value (LTC1174HVI)
LTC1174I/LTC1174HVI
●
●
●
●
●
●
●
●
MIN
1.18
0.75
0.50
0.54
0.5
2.0
1.8
t
OFF
R
ON
Switch Off-Time (Note 6)
Switch On Resistance
TYP
1.25
1.2
0.8
0.60
0.34
0.60
0.34
4
4
0.9
MAX
1.31
2.0
1.6
0.84
0.86
6.0
6.2
1.7
UNITS
V
mA
mA
A
A
A
A
µs
µs
Ω
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC1174CN8, LTC1174CN8-3.3, LTC1174CN8-5:
T
J
= T
A
+ (P
D
×
110°C/W)
LTC1174CS8, LTC1174CS8-3.3, LTC1174CS8-5:
T
J
= T
A
+ (P
D
×
150°C/W)
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3
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.
TYPICAL PERFOR A CE CHARACTERISTICS
Efficiency vs Load Current
100
95
100
95
V
IN
= 6V
EFFICIENCY (%)
EFFICIENCY (%)
V
IN
= 9V
85
80
75
70
EFFICIENCY (%)
90
L = 50µH
V
OUT
= 5V
I
PGM
= 0V
COIL = CTX50-4
1
10
LOAD CURRENT (mA)
100 200
1174 G01
Efficiency vs Load Current
100
V
IN
= 5V
100
90
EFFICIENCY (%)
EFFICIENCY (%)
80
80
V
IN
= 9V
EFFICIENCY (%)
V
IN
= 9V
70
L = 50µH
V
OUT
= 3.3V
I
PGM
= 0V
COIL = CTX50-4
1
10
100
LOAD CURRENT (mA)
300
1174 G04
60
50
4
U W
Efficiency vs Load Current
100
95
V
IN
= 6V
V
IN
= 9V
85
80
75
70
1
10
100
LOAD CURRENT (mA)
400
1174 G02
Efficiency vs Load Current
V
IN
= 6V
90
V
IN
= 9V
85
80
75
70
1
10
100
LOAD CURRENT (mA)
500
1174 G03
90
L = 50µH
V
OUT
= 5V
I
PGM
= V
IN
COIL = CTX50-4
L = 100µH
V
OUT
= 5V
I
PGM
= V
IN
COIL = CTX100-4
Efficiency vs Load Current
100
V
IN
= 5V
Efficiency vs Load Current
90
90
V
IN
= 5V
80
V
IN
= 9V
70
L = 50µH
V
OUT
= 3.3V
I
PGM
= V
IN
COIL = CTX50-4
1
10
100
LOAD CURRENT (mA)
500
1174 G05
70
L = 100µH
V
OUT
= 3.3V
I
PGM
= V
IN
COIL = CTX100-4
1
10
100
LOAD CURRENT (mA)
500
1174 G06
60
60
50
50
1174fe
LTC1174
LTC1174-3.3/LTC1174-5
TYPICAL PERFOR A CE CHARACTERISTICS
Line Regulation
6
4
2
I
LOAD
= 100mA
I
PGM
= 0V
LEAKAGE CURRENT (nA)
EFFICIENCY (%)
0
∆V
OUT
(mV)
–2
–4
–6
–8
–10
–12
–14
0
2
8
6
4
10
INPUT VOLTAGE (V)
12
14
Efficiency vs Input Voltage
95
94
93
92
91
90
0.2
89
5
6
7
8
9 10 11 12
INPUT VOLTAGE (V)
13
14
0
I
LOAD
= 100mA
I
PGM
= 0V
V
OUT
= 5V
L = 100µH
COIL = CTX100-4
1.8
1.6
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
EFFICIENCY (%)
I
LOAD
= 300mA
I
PGM
= V
IN
Operating Frequency
vs V
IN
– V
OUT
2.0
V
OUT
= 5V
NORMALIZED FREQUENCY
1.7
1.6
1.5
1.5
RDS
(ON)
(Ω)
OFF-TIME (µs)
T
A
= 25°C
1.0
T
A
= 70°C
0.5
0
0
1
5
7
3
6
2
4
(V
IN
– V
OUT
) VOLTAGE (V)
8
9
U W
1174 G07
1174 G10
Switch Leakage Current
vs Temperature
180
160
140
120
100
80
60
40
20
0
0
20
60
40
TEMPERATURE (°C)
80
100
1174 G08
Efficiency vs Input Voltage
95
94
93
92
91
90
89
88
87
5
6
7
9 10 11 12
8
INPUT VOLTAGE (V)
13
14
V
OUT
= 5V
I
PGM
= 0V
I
LOAD
= 75mA
CORE = CTX (Kool Mµ
®
)
L = 50µH
L = 100µH
V
IN
= 13.5V
1174 G09
Supply Current in Shutdown
500
SHUTDOWN = 0V
T
A
= 25°C
CURRENT INTO PIN 6 ONLY
450
400
350
300
250
200
150
100
50
0
0
2
4
6
8
10
INPUT VOLTAGE (V)
12
14
DC Supply Current
ACTIVE MODE
I
PGM
= 0V
I
PGM
= V
IN
1.4
1.2
1.0
0.8
0.6
0.4
SLEEP MODE
T
A
= 25°C
0
2
8
6
4
10
INPUT VOLTAGE (V)
12
14
1174 G11
1174 G12
Switch Resistance vs
Input Voltage
50
T
A
= 25°C
Off-Time vs Output Voltage
40
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
4
6
8
10 12 14 16
INPUT VOLTAGE (V)
18
20
LTC1174
LTC1174HV
30
20
LTC1174-5
LTC1174HV-5
10
LTC1174-3.3
LTC1174HV-3.3
0
1
3
4
2
OUTPUT VOLTAGE (V)
5
1174 G15
0
1174 G13
1174 G14
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5
