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LTC1911EMS8-1.8#TRPBF

P1-P3P4-P6P7-P9P10-P12
1
LTC1911-1.5/LTC1911-1.8
1911f
APPLICATIO S
U
FEATURES
DESCRIPTIO
U
TYPICAL APPLICATIO
U
Low Noise, High Efficiency,
Inductorless Step-Down
DC/DC Converter
The LTC
®
1911 is a switched capacitor step-down DC/DC
converter that produces a 1.5V or 1.8V regulated output
from a 2.7V to 5.5V input. The part uses switched capaci-
tor fractional conversion to achieve high efficiency over the
entire input range. No inductors are required. Internal cir-
cuitry controls the step-down conversion ratio to optimize
efficiency as the input voltage and load conditions vary.*
Typical efficiency is over 25% higher than that of a linear
regulator.
A unique constant frequency architecture provides a low
noise regulated output as well as lower input noise than
conventional charge pump regulators. High frequency
operation (f
OSC
= 1.5MHz) simplifies output filtering to
further reduce conducted noise. To optimize efficiency,
the part enters Burst Mode
®
operation under light load
conditions.
Low operating current (180µA with no load, 10µA in
shutdown) and low external parts count (two 1µF flying
capacitors and two 10µF bypass capacitors) make the
LTC1911 ideally suited for space constrained battery-
powered applications. The part is short-circuit and
overtemperature protected, and is available in an 8-pin
MSOP package.
■
Low Noise Constant Frequency Operation
■
2.7V to 5.5V Input Voltage Range
■
No Inductors
■
Typical Efficiency 25% Higher Than LDOs
■
Shutdown Disconnects Load from V
IN
■
Output Voltage: 1.8V ±4% or 1.5V ±4%
■
Output Current: 250mA
■
Low Operating Current: I
IN
= 180µA Typ
■
Low Shutdown Current: I
IN
= 10µA Typ
■
Oscillator Frequency: 1.5MHz
■
Soft-Start Limits Inrush Current at Turn On
■
Short-Circuit and Overtemperature Protected
■
Available in an 8-Pin MSOP Package
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
Handheld Computers
■
Cellular Phones
■
Smart Card Readers
■
Portable Electronic Equipment
■
Handheld Medical Instruments
■
Low Power DSP Supplies
V
IN
C2
+
C2
–
GND
8
6
7
5
1
2
3
4
SS/SHDN
V
OUT
C1
+
C1
–
LTC1911-1.8
1µF*
1-CELL Li-Ion
OR
3-CELL NiMH
10µF*
*CERAMIC CAPACITOR
10µF*
1911 TA01
V
OUT
= 1.8V
I
OUT
= 250mA
1µF*
2.7V TO 5.5V INPUT
Single Cell Li-Ion to 1.8V DC/DC Converter
Efficiency
Burst Mode is a registered trademark of Linear Technology Corporation.
*U.S. Patent #6,438,005
INPUT VOLTAGE (V)
2
30
EFFICIENCY (%)
40
50
60
70
80
90
3456
1911 G05
IDEAL LDO
250mA100mA
V
OUT
= 1.8V
2
LTC1911-1.5/LTC1911-1.8
1911f
PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Operating Voltage ● 2.7 5.5 V
V
OUT
LTC1911-1.5, 0mA ≤ I
OUT
≤ 250mA, V
IN
= 2.7V to 5.5V ● 1.44 1.5 1.56 V
LTC1911-1.8, 0mA ≤ I
OUT
≤ 250mA, V
IN
= 2.7V to 5.5V ● 1.73 1.8 1.87 V
V
IN
Operating Current I
OUT
= 0mA, V
IN
= 2.7V to 5.5V ● 180 350 µA
V
IN
Shutdown Current SS/SHDN = 0V, V
IN
= 2.7V to 5.5V ● 10 20 µA
Output Ripple I
OUT
= 10mA 5 mV
P-P
I
OUT
= 250mA 12 mV
P-P
V
OUT
Short-Circuit Current V
OUT
= 0V 600 mA
Switching Frequency Oscillator Free Running 1.2 1.5 1.8 MHz
SS/SHDN Input Threshold ● 0.3 0.6 1 V
SS/SHDN Soft-Start Current V
SS/SHDN
= 0V (Note 3) ● –5 –2 –1 µA
V
SS/SHDN
= V
IN
0.01 µA
Turn-On Time C
SS
= 0pF, V
IN
= 3.3V 0.03 ms
C
SS
= 10nF, V
IN
= 3.3V 10 ms
Load Regulation 0V ≤ I
OUT
≤ 250mA 0.13 mV/mA
Line Regulation 0V ≤ I
OUT
≤ 250mA 0.3 %/V
(Note 1)
V
IN
to GND...................................................–0.3V to 6V
SS/SHDN to GND........................ – 0.3V to (V
IN
+ 0.3V)
V
OUT
Short-Circuit Duration............................ Indefinite
Operating Temperature Range (Note 2) .. –40°C to 85°C
Storage Temperature Range ................. –40°C to 150°C
Lead Temperature (Soldering, 10 sec)..................300°C
ORDER PART
NUMBER
LTC1911EMS8-1.5
LTC1911EMS8-1.8
T
JMAX
= 125°C, θ
JA
= 160°C/W
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are T
A
= 25°C. V
IN
= 3.6V, C1 = 1µF, C2 = 1µF, C
IN
= 10µF, C
OUT
= 10µF unless
otherwise noted.
ABSOLUTE AXI U RATI GS
WWWU
PACKAGE/ORDER I FOR ATIO
UU
W
MS8 PART MARKING
1
2
3
4
V
IN
C2
+
C2
–
GND
8
7
6
5
SS/SHDN
C1
+
V
OUT
C1
–
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
LTMY
LTNU
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC1911E is guaranteed to meet specified performance 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.
Note 3: Currents flowing into the device are positive polarity. Currents
flowing out of the device are negative polarity.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
3
LTC1911-1.5/LTC1911-1.8
1911f
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Input Operating Current
vs Input Voltage
Input Shutdown Current
vs Input Voltage
LTC1911-1.8
Output Voltage vs Input Voltage
LTC1911-1.5
Output Voltage vs Input Voltage
LTC1911-1.5 Efficiency vs Input
Voltage (Falling Input Voltage)
LTC1911-1.8
Efficiency vs Output Current
LTC1911-1.8
Output Voltage vs Output Current
INPUT VOLTAGE (V)
2
INPUT CURRENT (µA)
180
190
200
6
1911 G01
170
160
3
4
5
150
210
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
INPUT VOLTAGE (V)
2
INPUT CURRENT (µA)
9
11
6
1911 G02
7
5
3
4
5
15
13
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
V
OUT
= 0V
V
(SS/SHDN)
= 0V
INPUT VOLTAGE (V)
2
OUTPUT VOLTAGE (V)
1.80
1.85
6
1911 G03
1.75
1.70
3
4
5
1.90
T
A
= –40°C
T
A
= 25°C
T
A
= 85°C
I
OUT
= 250mA
INPUT VOLTAGE (V)
2
EFFICIENCY (%)
60
70
80
6
1911 G05
50
40
20
3
4
5
30
100
90
IDEAL LDO
100mA
250mA
OUTPUT CURRENT (mA)
1
EFFICIENCY (%)
50
60
1911 G06
40
30
10
100
1000
90
80
70
2.7V
3.2V
3.7V
4.2V
5.1V
5.5V
V
IN
:
LTC1911-1.5
Efficiency vs Output Current
OUTPUT CURRENT (mA)
0.1
OUTPUT VOLTAGE (V)
1.78
1.80
1000
1911 G08
1.76
1.74
1
10
100
1.84
V
IN
= 3.6V
1.82
T
A
= –40°C
T
A
= 25°C
T
A
= 85°C
LTC1911-1.5
Output Voltage vs Output Current
INPUT VOLTAGE (V)
2
OUTPUT VOLTAGE (V)
1.49
1.51
6
LTXXXX • TPCXX
1.47
1.45
3
4
5
1.55
1.53
T
A
= –40°C
T
A
= 25°C
T
A
= 85°C
I
OUT
= 250mA
OUTPUT CURRENT (mA)
1
30
EFFICIENCY (%)
40
50
60
70
90
10 100
1911 G07
1000
80
2.8V
3.3V
3.7V
4.3V
5.1V
5.5V
V
IN
:
OUTPUT CURRENT (mA)
0.1
OUTPUT VOLTAGE (V)
1.48
1.50
1000
1911 G09
1.46
1.44
1
10
100
1.54
1.52
T
A
= –40°C
T
A
= 85°C T
A
= 25°C
V
IN
= 3.6V
P1-P3P4-P6P7-P9P10-P12

LTC1911EMS8-1.8#TRPBF

Mfr. #:
Buy LTC1911EMS8-1.8#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators L N, Hi Eff, Inductorless Buck DC/DC Con
Lifecycle:
New from this manufacturer.
Delivery:
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