Commercial Temperature Range (Note 7) .... 0°C to 70°C
Industrial Temperature Range (Note 7) ... –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
1
C1
+
2
C1
–
3
GND 4
8
7
6
5
SHDN
REG
OUT
ADJ (COMP*)
NC 1
C1
+
2
C1
–
C2
–
3
5
C2
+
4
GND 6
R0 7
14 V
CC
13 SHDN
12 REG
11 OUT
10 ADJ
9
8
R
ADJ
R1
S8 PACKAGE
8-LEAD PLASTIC SO
*FOR FIXED VERSIONS
T
JMAX
= 150°C,
θ
JA
= 150°C/W
S PACKAGE
14-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 110°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC1261CS8#PBF
LTC1261IS8#PBF
LTC1261CS8-4#PBF
LTC1261CS8-4.5#PBF
LTC1261CS#PBF
TAPE AND REEL
LTC1261CS8#TRPBF
LTC1261IS8#TRPBF
LTC1261CS8-4#TRPBF
LTC1261CS8-4.5#TRPBF
LTC1261CS#TRPBF
PART MARKING*
1261
1261
12614
126145
LTC1261CS
PACKAGE DESCRIPTION
8-Lead Plastic S0
8-Lead Plastic S0
8-Lead Plastic S0
8-Lead Plastic S0
14-Lead Plastic S0
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
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/
1261fb
2
For more information
www.linear.com/LTC1261
LTC1261
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 3V to 6.5V unless otherwise specified.
0°C ≤ T
A
≤ 70°C
MIN
TYP
MAX
l
1.20
1.24
1.28
l
No Load, SHDN Floating, Doubler Mode
600
1000
l
No Load, SHDN Floating, Tripler Mode
900
1500
l
No Load, V
SHDN
= V
CC
5
20
Internal Oscillator Frequency
550
f
OSC
Power Efficiency
65
P
EFF
l
REG Output Low Voltage
I
REG
= 1mA
0.1
0.8
V
OL
l
REG Sink Current
V
REG
= 0.8V, V
CC
= 3.3V
5
8
I
REG
l
V
REG
= 0.8V, V
CC
= 5.0V
8
15
l
Adjust Pin Current
V
ADJ
= 1.24V
0.01
1
I
ADJ
l
SHDN Input High Voltage
2
V
IH
l
SHDN Input Low Voltage
0.8
V
IL
l
SHDN Input Current
V
SHDN
= V
CC
5
20
I
IN
Turn-On Time
I
OUT
= 15mA
500
t
ON
Doubler Mode. V
CC
= 5V ±10%, C1 = 0.1µF, C2 = 0 (Note 4), C
OUT
= 3.3µF unless otherwise specified.
l
Output Regulation (Note 2)
–1.24V ≥ V
OUT
≥ –4V, 0 ≤ I
OUT
≤ 8mA
1
5
∆V
OUT
l
–1.24V ≥ V
OUT
≥ –4V, 0 ≤ I
OUT
≤ 7mA
2
–4V ≥ V
OUT
≥ –5V, 0 ≤ I
OUT
≤ 8mA (Note 6)
l
Output Short-Circuit Current
V
OUT
= 0V
60
125
I
SC
Output Ripple Voltage
I
OUT
= 5mA, V
OUT
= –4V
5
V
RIP
LTC1261CS Only. Tripler Mode. V
CC
= 2.7V, C1 = C2 = 0.1µF (Note 4), C
OUT
= 3.3µF unless otherwise specified.
l
Output Regulation
–1.24V ≥ V
OUT
≥ –4V, 0 ≤ I
OUT
≤ 5mA
1
5
∆V
OUT
l
Output Short-Circuit Current
V
OUT
= 0V
60
125
I
SC
Output Ripple Voltage
I
OUT
= 5mA, V
OUT
= –4V
5
V
RIP
LTC1261CS Only. Tripler Mode. V
CC
= 3.3V ±10%, C1 = C2 = 0.1µF (Note 4), C
OUT
= 3.3µF unless otherwise specified.
l
Output Regulation (Note 2)
–1.24V ≥ V
OUT
≥ –4.5V, 0 ≤ I
OUT
≤ 6mA
1
5
∆V
OUT
l
–4.5V ≥ V
OUT
≥ –5V, 0 ≤ I
OUT
≤ 3.5mA
2
5
l
Output Short-Circuit Current
V
OUT
= 0V
35
75
I
SC
Output Ripple Voltage
I
OUT
= 5mA, V
OUT
= –4V
5
V
RIP
LTC1261CS Only. Tripler Mode. V
CC
= 5V ±10%, C1 = C2 = 0.1µF (Note 4), C
OUT
= 3.3µF unless otherwise specified.
l
Output Regulation
–1.24V ≥ V
OUT
≥ –4V, 0 ≤ I
OUT
≤ 12mA
1
5
∆V
OUT
l
–4V ≥ V
OUT
≥ –5V, 0 ≤ I
OUT
≤ 10mA
2
5
l
Output Short-Circuit Current
V
OUT
= 0V
35
75
I
SC
Output Ripple Voltage
I
OUT
= 5mA, V
OUT
= –4V
5
V
RIP
PARAMETER
Reference Voltage
Supply Current
CONDITIONS
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:
All typicals are given at T
A
= 25°C.
Note 4:
C1 = C2 = 0.1µF means the specifications apply to tripler mode
where V
CC
– V
OUT
= 3V
CC
(LTC1261CS only; the LTC1261CS8 cannot be
connected in tripler mode) with C1 connected between C1
+
and C1
–
and
C2 connected between C2
+
and C2
–
. C2 = 0 implies doubler mode where
V
CC
– V
OUT
= 2V
CC
; for the LTC1261CS this means C1 connects from C1
+
–40°C ≤ T
A
≤ 85°C
(Note 7)
MIN
TYP
MAX
1.20
1.24
1.28
600
1500
900
2000
5
20
550
65
0.1
0.8
5
8
8
15
0.01
1
2
0.8
5
25
500
ELECTRICAL CHARACTERISTICS
SYMBOL
V
REF
I
S
UNITS
V
µA
µA
µA
kHz
%
V
mA
mA
µA
V
V
µA
µs
%
%
%
mA
mV
%
mA
mV
%
%
mA
mV
%
%
mA
mV
1
2
60
5
1
60
5
1
2
35
5
1
2
35
5
5
125
5
125
5
75
5
5
75
to C2
–
with C1
–
and C2
+
floating. For the LTC1261CS8 in doubler mode,
C1 connects from C1
+
to C1
–
; there are no C2 pins.
Note 5:
Setting output to <–7V will exceed the absolute voltage maximum
rating with a 5V supply. With supplies higher than 5V, the output should
never be set to exceed V
CC
– 12V.
Note 6:
For output voltages below –4.5V the LTC1261 may reach 50%
duty cycle and fall out of regulation with heavy load or low input voltages.
Beyond this point, the output will follow the input with no regulation.
Note 7:
The LTC1261C 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 LTC1261IS8
is guaranteed to meet specifications from –40°C and 85°C.
1261fb
For more information
www.linear.com/LTC1261
3
LTC1261
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage
vs Output Current
–3.5
–3.6
–3.7
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
–3.8
–3.9
–4.0
–4.1
–4.2
–4.3
–4.4
–4.5
0
1
2
3 4 5 6 7 8
OUTPUT CURRENT (mA)
9
10
V
CC
= 5V
DOUBLER MODE
V
CC
= 3.3V
TRIPLER MODE
T
A
= 25°C
–3.5
–3.6
–3.7
–3.8
–3.9
–4.0
–4.1
–4.2
–4.3
–4.4
–4.5
5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 6.8 7.0
SUPPLY VOLTAGE (V)
LT1261 • TP02
(See Test Circuits)
Output Voltage (Tripler Mode)
vs Supply Voltage
–3.5
–3.6
–3.7
OUTPUT VOLTAGE (V)
–3.8
–3.9
–4.0
–4.1
–4.2
–4.3
–4.4
–4.5
3
4
6
5
SUPPLY VOLTAGE (V)
7
LTC1261 • TPC03
Output Voltage (Doubler Mode)
vs Supply Voltage
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
LT1261 • TP01
Maximum Output Current
vs Supply Voltage
50
MAXIMUM OUTPUT CURRENT (mA)
V
OUT
= –4V ±5%
T
A
= 25°C
TRIPLER MODE
30
DOUBLER MODE
20
1200
1000
SUPPLY CURRENT (µA)
900
800
Supply Current
vs Supply Voltage
1200
V
OUT
= –4V
T
A
= 25°C
SUPPLY CURRENT (µA)
1000
900
800
700
600
Supply Current
vs Temperature
V
OUT
= –4V
40
V
CC
= 5V
DOUBLER MODE
TRIPLER MODE
700
600
DOUBLER MODE
V
CC
= 3.3V
TRIPLER MODE
10
3.0
3.5
4.0 4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
6.5
7.0
500
3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0
SUPPLY VOLTAGE (V)
LTC1261 • TPC05
500
–40 –20
40
20
60
0
TEMPERATURE (°C)
80
100
LTC1261 • TPC04
LTC1261 • TPC06
TEST CIRCUITS
Doubler Mode
5V
1
V
CC
C1
+
SHDN
8
7
V
OUT
= –4V ±5%
3.3µF
0.1µF
2
3
Tripler Mode
V
IN
= 3.3V
14
C1
+
V
CC
ADJ
10
10µF
+
10µF
+
2
0.1µF
REG
LTC1261-4
3
6
OUT
C1
–
4
9
R
ADJ
C1
–
LTC1261CS
4
8
C2
+
R1
5
C2
–
R0
OUT
GND
6
LTC1261 • TC02
4
For more information
www.linear.com/LTC1261
+
+
GND
COMP
5
0.1µF
7
11
3.3µF
V
OUT
= –4V ±5%
LTC1261 • TCO1
1261fb
LTC1261
PIN FUNCTIONS
(CS/CS8)
NC (Pin 1/NA):
No Internal Connection.
C1
+
(Pin 2/Pin 2):
C1 Positive Input. Connect a 0.1µF
capacitor between C1
+
and C1
–
. With the LTC1261CS in
doubler mode, connect a 0.1µF capacitor from C1
+
to C2
–
.
C1
–
(Pin 3/Pin 3):
C1 Negative Input. Connect a 0.1µF
capacitor from C1
+
to C1
–
. With the LTC1261CS in doubler
mode only, C1
–
should float.
C2
+
(Pin 4/NA):
C2 Positive Input. In tripler mode connect
a 0.1µF capacitor from C2
+
to C2
–
. This pin is used with
the LTC1261CS in tripler mode only; in doubler mode this
pin should float.
C2
–
(Pin 5/NA):
C2 Negative Input. In tripler mode con-
nect a 0.1µF capacitor from C2
+
to C2
–
. In doubler mode
connect a 0.1µF capacitor from C1
+
to C2
–
.
GND (Pin 6/Pin 4):
Ground. Connect to a low impedance
ground. A ground plane will help to minimize regulation
errors.
R0 (Pin 7/NA):
Internal Resistor String, 1st Tap. See Table 2
in the Applications Information section for information on
internal resistor string pin connections vs output voltage.
R1 (Pin 8/NA):
Internal Resistor String, 2nd Tap.
R
ADJ
(Pin 9/NA):
Internal Resistor String Output. Connect
this pin to ADJ to use the internal resistor divider. See Table
2 in the Applications Information section for information on
internal resistor string pin connections vs output voltage.
ADJ (COMP for Fixed Versions) (Pin 10/Pin 5):
Output
Adjust/Compensation Pin. For adjustable parts this pin is
used to set the output voltage. The output voltage should
be divided down with a resistor divider and fed back to
this pin to set the regulated output voltage. The resistor
divider can be external or the internal divider string can be
used if it can provide the required 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 parts have the internal resistor string con-
nected 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 adjustable and fixed output voltage parts.
See Applications Information section for more information
on compensation and output ripple.
OUT (Pin 11/Pin 6):
Negative Voltage Output. This pin
must be bypassed to ground with a 1µF or larger capaci-
tor; it must be at least 3.3µF to provide specified output
ripple. The size of the output capacitor has a strong effect
on output ripple. See the Applications Information section
for more details.
REG (Pin 12/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 8mA 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 12V above ground without damage.
SHDN (Pin 13/Pin 8):
Shutdown. When this pin is at ground
the LTC1261 operates normally. An internal 5µA pull-down
keeps SHDN low if it is left floating. When SHDN is pulled
high, the LTC1261 enters shutdown mode. In shutdown
the charge pump stops, the output collapses to 0V and
the quiescent current drops to 5µA typically.
V
CC
(Pin 14/Pin 1):
Power Supply. This requires an input
voltage between 3V and 6.5V. Certain combinations of
output voltage and operating mode may place additional
restrictions on the input voltage. V
CC
must be bypassed
to ground with at least a 0.1µF capacitor placed in close
proximity to the chip. See the Applications Information
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Embedded System
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