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LTC1258CS8-3#PBF

P1-P3P4-P6P7-P8
LTC1258 Series
4
1258sfb
Note 4: ESD (electrostatic discharge) sensitive device. Extensive use of
ESD protection devices are used internal to the LTC1258, however, high
electrostatic discharge can damage or degrade the device. Use proper ESD
handling precautions.
Note 5: Peak-to-peak noise is measured with a single pole highpass fi lter
at 0.1Hz and 2-pole lowpass fi lter at 10Hz.
Note 6: Temperature coeffi cient is the change in output voltage divided by
the nominal output voltage divided by the specifi ed temperature range.
Note 7: Load regulation is measured on a pulse basis from no load to the
specifi ed load current. Output changes due to die temperature change
must be taken into account separately.
Note 8: Dropout voltage is (V
IN
– V
OUT
) when V
OUT
falls to 0.1% below its
nominal value at V
IN
= V
OUT
+ 0.5V.
Note 9: Hysteresis in output voltage is created by package stress that
differs depending on whether the IC was previously at a higher or lower
temperature. Output voltage is always measured at 25°C, but the IC is
cycled hot or cold before successive measurements. Hysteresis is not
normally a problem for operational temperature excursions where the
instrument might be stored at high or low temperature.
ELECTRICAL CHARACTERISTICS
TYPICAL PERFORMANCE CHARACTERISTICS
LTC1258-2.5* Dropout Voltage vs
Output Source Current
LTC1258-2.5* Input Current vs
Temperature
LTC1258 Series Output Short-
Circuit Current vs Temperature
LTC1258-2.5* Output Short-
Circuit vs Input Voltage
LTC1258-2.5* Output Short-
Circuit Current vs Input Voltage
LTC1258 Series Load Regulation
OUTPUT SOURCE CURRENT (mA)
DROPOUT VOLTAGE (mV)
100
90
80
70
60
50
40
30
20
10
0
0 1 10 100
1258 G01
0.1
T
A
= 25oC
TEMPERATURE (°C)
–50 –25
INPUT CURRENT (μA)
150
1258 G02
025
50 75
100 125
8
7
6
5
4
3
2
1
0
V
IN
= 2.7V
TEMPERATURE (°C)
–50 –25
OUTPUT SHORT-CIRCUIT CURRENT (mA)
150
1258 G03
025
50 75
100 125
70
60
50
40
30
20
10
5
0
T
A
= 25°C
V
IN
= V
OUT(NOM)
+ 0.2V
OUTPUT
SHORTED
TO V
IN
OUTPUT
SHORTED
TO GND
INPUT VOLTAGE (V)
2
OUTPUT SHORT-CIRCUIT CURRENT (mA)
25
20
15
10
5
0
4
6810
1258-G04
12 14
T
A
= 25°C
OUTPUT SHORTED
TO V
IN
INPUT VOLTAGE (V)
2
OUTPUT SHORT-CIRCUIT CURRENT (mA)
42
41
4
6810
1258-G05
12 14
T
A
= 25°C
OUTPUT SHORTED
TO GND
OUTPUT CURRENT (mA)
$V
OUT
FROM NO LOAD (mV)
5
4
3
2
1
0
–1
–2
–3
–4
–5
0 1 10 100
1258 G06
0.1
T
A
= 25°C
V
IN
= V
OUT(NOM)
+ 0.2V
SINKING
SOURCING
*Similar performance characteristics can be expected for all voltage options.
LTC1258 Series
5
1258sfb
TYPICAL PERFORMANCE CHARACTERISTICS
LTC1258-2.5 Output Voltage vs
Input Voltage
LTC1258-2.5 Input Current vs
Input Voltage
LTC1258-2.5 PSRR vs Frequency
LTC1258-2.5 0.1Hz to 10Hz Noise
LTC1258-5 Input Current vs Input
Voltage in Dropout
LTC1258-2.5 Input Current vs
Input Voltage in Dropout
INPUT VOLTAGE (V)
2
OUTPUT VOLTAGE (V)
2.5010
2.5005
2.5000
2.4995
4
6810
1258 G07
12 14
T
A
= 25°C
INPUT VOLTAGE (V)
2
INPUT CURRENT (μA)
7
6
5
4
4
6810
1258 G08
12 14
T
A
= 25°C
FREQUENCY (Hz)
POWER SUPPLY REJECTION RATIO (dB)
60
50
40
30
20
10
0
10 1k 10k
1258 G09
100
V
IN
= 2.7V
5μV/DIV
1258 G10
1SEC/DIV
V
IN
= 2.7V
INPUT VOLTAGE (V)
012345678910
INPUT CURRENT (μA)
1258 G11
1400
1200
1000
800
600
400
200
0
T
A
= –55°C
T
A
= 25°C
T
A
= 125°C
INPUT VOLTAGE (V)
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
INPUT CURRENT (μA)
1258 G12
250
200
150
100
50
0
T
A
= 25°C
T
A
= –55°C
T
A
= 125°C
PIN FUNCTIONS
OUT (Pin 1): Reference Output. The output can source
up to 10mA and sink up to 2mA. It is stable with output
bypass capacitor ranging from 0μF to 1μF.
IN (Pin 2): Positive Supply. Bypassing with a 0.1μF ca-
pacitor is recommended if the output loading changes.
(V
OUT
+ 0.2V) ≤ V
IN
≤ 12.6V.
DNC (Pin 3): (LTC1258-2.5/LTC1258-3/LTC1258-4.1/
LTC1258-5) Do Not Connect. Connected internally for post
package trim. This pin must be left unconnected.
FB (Pin 3): (LT1258) Resistor Divider Feedback Pin. Con-
nect a resistor divider from OUT to GND and the center
tap to FB. This pin sets the output potential.
VV
RR
R
OUT
=
+
⎛
⎝
⎜
⎞
⎠
⎟
2 385
12
2
.;
R1 is connected from OUT
to
FB and R2 from FB to GND.
GND (Pin 4): Negative Supply or Ground Connection.
DNC (Pins 5, 6, 7, 8): Do Not Connect. Connected in-
ternally for post package trim. These pins must be left
unconnected.
LTC1258 Series
6
1258sfb
BLOCK DIAGRAM
–
+
IN
1
1258 BD
2
4
OUT
3 (LTC1258)FB
2.385V
GND
R1
R2
NOTE: R1 AND R2 ARE NOT CONNECTED FOR LTC1258
APPLICATIONS INFORMATION
Longer Battery Life
Series references have an advantage over shunt style
references. To operate, shunt references require a resistor
between the power supply and the output. This resistor
must be chosen to supply the maximum current that is
demanded by the circuit being regulated. When the circuit
being controlled is not operating at this maximum current,
the shunt reference must always sink this current, resulting
in high power dissipation and short battery life.
The LTC1258 series low dropout references do not require
a current setting resistor and can operate with any supply
voltage from (V
OUT(NOMINAL)
+ 0.2V) to 12.6V. When the
circuitry being regulated does not demand current, the
LTC1258 series reduces its dissipation and battery life is
extended. If the reference is not delivering load current it
dissipates only 10.8μW when operating on a 2.7V supply
for LTC1258-2.5, yet the same connection can deliver
10mA of load current when demanded.
Output Bypass Capacitor
The LTC1258 series is designed to be stable with or without
capacitive loads. With no capacitive load, the reference
is ideal for fast settling applications, or where PC board
space is at a premium.
In applications with signifi cant output loading changes,
an output bypass capacitor of up to 1μF can be used to
improve the output transient response. Figure 1 shows
the response of the reference to a 1mA to 0μA load step
with a 1μF output capacitor. If more than 1μF of output
capacitance is required, a resistor in series with the capaci-
tor is recommended to reduce the output ringing. Figure 2
illustrates the use of a damping resistor for capacitive loads
greater than 1μF. Figure 3 shows the resistor and capacitor
values required to achieve critical damping.
1mA
0mA
10ms/DIV
1258 F01a
I
OUT
V
OUT
100mV/DIV
1mA
0mA
0.5ms/DIV
1258 F01b
I
OUT
V
OUT
100mV/DIV
Figure 1. Reference Output Load Transient Response, 1μF Output Capacitor
P1-P3P4-P6P7-P8

LTC1258CS8-3#PBF

Mfr. #:
Buy LTC1258CS8-3#PBF
Manufacturer:
Analog Devices Inc.
Description:
Voltage References Micropower Low Dropout 3V Reference
Lifecycle:
New from this manufacturer.
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