Commercial Temperature Range (Note 4) .... 0°C to 70°C
Industrial Temperature Range (Note 4) ... –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
V
CC
C1
+
C1
–
GND
1
2
3
4
8
7
6
5
SHDN
REG
OUT
ADJ (COMP)
V
CC
1
C1
+
2
C1
–
3
GND 4
8
7
6
5
SHDN
REG
OUT
ADJ (COMP)
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 200°C/W
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 135°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC1261LCMS8#PBF
LTC1261LIMS8#PBF
LTC1261LCMS8-4#PBF
LTC1261LIMS8-4#PBF
LTC1261LCMS8-4.5#PBF
LTC1261LIMS8-4.5#PBF
LTC1261LCS8#PBF
LTC1261LIS8#PBF
LTC1261LCS8-4#PBF
LTC1261LIS8-4#PBF
LTC1261LCS8-4.5#PBF
LTC1261LIS8-4.5#PBF
TAPE AND REEL
LTC1261LCMS8#TRPBF
LTC1261LIMS8#TRPBF
LTC1261LCMS8-4#TRPBF
LTC1261LIMS8-4#TRPBF
LTC1261LIMS8-4.5#TRPBF
LTC1261LCS8#TRPBF
LTC1261LIS8#TRPBF
LTC1261LCS8-4#TRPBF
LTC1261LIS8-4#TRPBF
LTC1261LCS8-4.5#TRPBF
LTC1261LIS8-4.5#TRPBF
PART MARKING*
LTFM
LTFM
LTFN
LTFN
LTFP
1261L
1261L
1261L4
1261L4
261L45
261L45
PACKAGE DESCRIPTION
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SO
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
LTC1261LCMS8-4.5#TRPBF LTFP
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
1261lfa
2
LTC1261L
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
V
CC
Supply Voltage
LTC1261LCMS8/LTC1261LCS8
LTC1261LCMS8-4/LTC1261LCS8-4
(Note 5)
LTC1261LCMS8-4.5/LTC1261LCS8-4.5 (Note 5)
Reference Voltage
Supply Current
Internal Oscillator Frequency
REG Output Low Voltage
REG Sink Current
Adjust Pin Current
SHDN Input High Voltage
SHDN Input Low Voltage
SHDN Input Current
Turn-On Time
V
CC
= 5.25V, No Load, SHDN Floating
V
CC
= 5.25V, No Load, V
SHDN
= V
CC
V
CC
= 5V, V
OUT
= –4V
I
REG
= 1mA, V
CC
= 5V, V
OUT
= –4V
V
REG
= 0.8V, V
CC
= 3.3V
V
REG
= 0.8V, V
CC
= 5V
V
ADJ
= 1.23V
V
CC
= 5V
V
CC
= 5V
V
SHDN
= V
CC
V
CC
= 5V, I
OUT
= 10mA, –1.5V ≤ V
OUT
≤ –4V (LTC1261L)
V
CC
= 5V, I
OUT
= 5mA, V
OUT
= –4.5V (LTC1261L)
V
CC
= 5V, I
OUT
= 10mA, V
OUT
= –4V (LTC1261L-4)
V
CC
= 5V, I
OUT
= 5mA, V
OUT
= –4.5V (LTC1261L-4.5)
2.70V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 10mA
3.25V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 20mA
2.70V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 5mA
2.95V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 10mA
3.50V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 20mA
2.95V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 5mA
3.30V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 10mA
3.85V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 20mA
3.40V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 5mA
3.70V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 10mA
4.25V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 20mA
3.85V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 5mA
4.10V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 10mA
4.60V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 20mA
Output Regulation
(LTC1261L/LTC1261L-4)
Output Regulation
(LTC1261L/LTC1261L-4.5)
I
SC
Output Short-Circuit Current
4.35V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 5mA
4.60V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 10mA
5.10V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 20mA
4.75V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 5mA
5.05V ≤ V
CC
≤ 5.25V, 0mA ≤ I
OUT
≤ 10mA
V
OUT
= 0V, V
CC
= 5.25V
l
l
l
l
l
l
l
l
l
l
l
l
–1.552
l
–1.552
l
–2.070
l
–2.070
l
–2.070
l
–2.587
l
–2.587
l
–2.587
l
–3.105
l
–3.105
l
–3.105
l
–3.622
l
–3.622
l
–3.622
l
–4.140
l
–4.140
l
–4.140
l
–4.657
l
–4.657
l
l
l
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, C1 = 0.1µF, C
OUT
= 3.3µF unless otherwise noted. (Notes 2, 4)
CONDITIONS
l
l
l
MIN
2.7
4.35
4.75
TYP
MAX
5.25
5.25
5.25
UNITS
V
V
V
V
µA
µA
kHz
V
mA
mA
V
REF
I
CC
f
OSC
V
OL
I
REG
I
ADJ
V
IH
V
IL
I
IN
t
ON
1.23
650
5
650
0.1
4
5
2
0.8
2.5
250
250
250
250
–1.5
–1.5
–2.0
–2.0
–2.0
–2.5
–2.5
–2.5
–3.0
–3.0
–3.0
–3.5
–3.5
–3.5
–4.0
–4.0
–4.0
–4.5
–4.5
100
25
1500
1500
1500
1500
–1.448
–1.448
–1.930
–1.930
–1.91
–2.413
–2.413
–2.41
–2.895
–2.895
–2.885
–3.378
–3.378
–3.365
–3.860
–3.860
–3.83
–4.343
–4.343
220
8
12
±0.01
±1
0.8
1500
20
µA
V
V
µA
µs
µs
µs
µs
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
mA
V
OUT
Output Regulation (LTC1261L)
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:
All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.
Note 3:
The output should never be set to exceed V
CC
– 10.8V.
Note 4:
The LTC1261LC is guaranteed to meet specifications from 0°C
to 70°C and is designed, characterized and expected to meet industrial
temperature limits, but is not tested at –40°C and 85°C. The LTC1261LI
is guaranteed to meet specifications from –40°C and 85°C.
Note 5:
The LTC1261L-4 and LTC1261L-4.5 will operate with less than the
minimum V
CC
specified in the electrical characteristics table, but they are
not guaranteed to meet the ±4.5% V
OUT
specification.
1261lfa
3
LTC1261L
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage vs Output Current
0
– 0.25
– 0.50
OUTPUT VOLTAGE (V)
– 0.75
–1.00
–1.25
–1.50
–1.75
– 2.00
– 2.25
0
5
V
CC
= 3V
V
CC
= 2.7V
T
A
= 25°C
V
OUT
= – 2V
– 3.0
– 3.1
– 3.2
OUTPUT VOLTAGE (V)
– 3.3
– 3.4
– 3.5
– 3.6
– 3.7
– 3.8
– 3.9
– 4.0
– 4.1
10
15
25
20
OUTPUT CURRENT (mA)
30
– 4.2
0
5
10
15
20
25
OUTPUT CURRENT (mA)
30
–2.10
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
1261L G03
(See Test Circuits)
Output Voltage vs Supply Voltage
–1.90
V
OUT
= – 2V
Output Voltage vs Output Current
T
A
= 25°C
V
OUT
= – 4V
OUTPUT VOLTAGE (V)
–1.95
T
A
= – 40°C
–2.00
T
A
= 85°C
–2.05
T
A
= 25°C
V
CC
= 4.5V
V
CC
= 5V
1261L G01
1261L G02
Output Voltage vs Supply Voltage
– 3.85
– 3.90
OUTPUT VOLTAGE (V)
– 3.95
– 4.00
T
A
= 85°C
– 4.05
– 4.10
– 4.15
4.5
V
OUT
= – 4V
POSITIVE SUPPLY VOLTAGE (V)
5.6
5.2
4.8
4.4
4.0
3.6
3.2
2.8
2.4
4.6
4.7 4.8 4.9 5.0 5.1
SUPPLY VOLTAGE (V)
5.2
5.3
2.0
Minimum Required V
CC
vs V
OUT
and I
OUT
80
MAXIMUM OUTPUT CURRENT (mA)
70
60
50
40
30
20
10
Maximum Output Current
vs Supply Voltage
T
A
= 25°C
T
A
= – 40°C
T
A
= 25°C
V
OUT
= – 2V
I
OUT
= 20mA
I
OUT
= 5mA
I
OUT
= 10mA
V
OUT
= – 3V
V
OUT
= – 4V
–5
–4
–3
–2
–1
OUTPUT VOLTAGE (V)
0
1261L G05
0
2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8 5.1 5.4
SUPPLY VOLTAGE (V)
1261L G06
1261L G04
Supply Current vs Supply Voltage
3.0
2.5
SUPPLY CURRENT (mA)
2.0
1.5
1.0
0.5
0
2.5
T
A
= 85°C
T
A
= – 40°C
T
A
= 25°C
V
OUT
= – 2V
I
OUT
= 0
SUPPLY CURRENT (mA)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
1261L G07
Supply Current vs Supply Voltage
V
OUT
= – 4.5V
I
OUT
= 0
REFERENCE VOLTAGE (V)
1.25
Reference Voltage
vs Temperature
V
CC
= 5V
ADJ = 0V
1.24
1.23
T
A
= 85°C
T
A
= 25°C
T
A
= – 40°C
4.5 4.6
4.7 4.8 4.9 5.0 5.1
SUPPLY VOLTAGE (V)
5.2
5.3
1.22
0
1.21
– 55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1261L G09
1261L G08
1261lfa
4
LTC1261L
TYPICAL PERFORMANCE CHARACTERISTICS
Oscillator Frequency
vs Temperature
725
OSCILLATOR FREQUENCY (kHz)
700
675
650
625
600
575
550
525
–40 –25 –10
5 20 35 50 65
TEMPERATURE (°C)
80
95
T
A
= 25°C
V
OUT
= – 4V
V
CC
= 5V
START-UP TIME (ms)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
2.5
3.5
4.5
4.0
SUPPLY VOLTAGE (V)
V
OUT
= – 2V
V
OUT
= – 4V
Start-Up Time vs Supply Voltage
SHORT-CIRCUIT CURRENT (mA)
T
A
= 25°C
I
OUT
= 10mA
160
140
120
100
80
60
40
20
3.0
5.0
1261L G11
Output Short-Circuit Current
vs Temperature
V
CC
= 5.25V
V
CC
= 5V
V
CC
= 3V
V
CC
= 2.7V
5 20 35 50 65
TEMPERATURE (°C)
80
95
0
– 40 – 25 –10
1261L G10
1261L G12
PIN FUNCTIONS
V
CC
(Pin 1):
Power Supply. This requires an input voltage
between 2.7V and 5.25V. V
CC
must be bypassed to ground
with at least a 1µF capacitor placed in close proximity to the
chip. See the Applications Information section for details.
C1
+
(Pin 2):
C1 Positive Input. Connect a 0.1µF capacitor
between C1
+
and C1
–
.
C1
–
(Pin 3):
C1 Negative Input. Connect a 0.1µF capacitor
from C1
+
to C1
–
.
GND (Pin 4):
Ground. Connect to a low impedance ground.
A ground plane will help to minimize regulation errors.
ADJ (COMP for Fixed Versions) (Pin 5):
Output Adjust/
Compensation Pin. For adjustable parts this pin is used to
set the output voltage. The output voltage is divided down
with an external resistor divider and fed back to this pin
to set the regulated output voltage. Typically the resistor
string should draw ≥10µA from the output to minimize
errors due to the bias current at the adjust pin. Fixed output
voltage parts have the internal resistor string connected
to this pin inside the package. The pin can be used to
trim the output voltage if desired. It can also be used as
an optional feedback compensation pin to reduce output
ripple on both the adjustable and fixed output voltage
parts. See the Applications Information section for more
information on compensation and output ripple.
OUT (Pin 6):
Negative Voltage Output. This pin must be
bypassed to ground with a 1µF or larger capacitor. The
value of the output capacitor and its ESR have a strong
effect on output ripple. See the Applications Information
section for more details.
REG (Pin 7):
This is an open-drain output that pulls low
when the output voltage is within 5% of the set value. It
will sink 5mA to ground with a 5V supply. The external
circuitry must provide a pull-up or REG will not swing high.
The voltage at REG may exceed V
CC
and can be pulled up
to 6V above ground without damage.
SHDN (Pin 8):
Shutdown. When this pin is at ground the
LTC1261L operates normally. An internal 5µA pull-down
keeps SHDN low if it is left floating. When SHDN is pulled
high, the LTC1261L enters shutdown mode. In shutdown,
the charge pump is disabled, the output collapses to 0V
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