LTC1798CS8-3 [Linear]
Micropower Low Dropout References; 微功率低压差参考型号: | LTC1798CS8-3 |
厂家: | Linear |
描述: | Micropower Low Dropout References |
文件: | 总8页 (文件大小:153K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LTC1798 Series
Micropower Low
Dropout References
U
DESCRIPTIO
FEATURES
The LTC®1798/LTC1798-2.5/LTC1798-3/LTC1798-4.1/
LTC1798-5aremicropowerbandgapreferencesthatcom-
bine high accuracy and low drift with very low supply
currentandsmallpackagesize.Thecombinationofultralow
quiescent current and low dropout voltage of only 200mV
(max) makes them ideal for battery-powered equipment.
The output voltage is set by an external resistor divider for
the adjustable LTC1798.
■
200mV Max Dropout at 10mA Output Current
■
4µA Typical Quiescent Current
■
0.15% Max Initial Accuracy
■
No Output Capacitor Required
■
Output Sources 10mA, Sinks 2mA
■
40ppm/°C Max Drift
■
Voltage Options: 2.5V, 3V, 4.1V, 5V and Adjustable
U
This series of references uses curvature compensation to
obtain low temperature coefficient and trimmed thin-film
resistors to achieve high output accuracy. These refer-
ences can source up to 10mA and sink up to 2mA, making
them ideal for precision regulator applications. They are
stable without an output bypass capacitor, but are also
stablewithcapacitanceupto1µF.Thisfeatureisimportant
incriticalapplicationswherePCboardspaceisapremium
and fast settling is demanded.
APPLICATIO S
■
Battery-Powered Systems
■
Handheld Instruments
■
Precision Power Supplies
A/D and D/A Converters
■
The LTC1798 series references provided power dissipa-
tion advantages over shunt references. In addition to
supply current, shunt references must also idle the entire
load current to operate.
The LTC1798 series is available in the SO-8 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
LTC1798-2.5 Temperature Drift
4
2.5V Battery-Powered Reference
3
2
LTC1798-2.5
6
2
2.7V
TO 12.6V
IN
2.5V
OUT
1
0.1µF
0
GND
4
1798 TA01
–1
–2
–3
–4
–40 –20
0
20
40
60
80 100
TEMPERATURE (°C)
1798 TA02
1
LTC1798 Series
W W
U W
U
W
U
ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Note 1)
ORDER PART
Supply Voltage ....................................................... 13V
Input Voltages .......................................... –0.3v to 13V
Output Voltages ........................................ –0.3V to 13V
Output Short-Circuit Duration.......................... Indefinite
Operating Temperature Range
(Note 2) ........................................... –40°C to 100°C
Specified Temperature Range..................... 0°C to 70°C
Storage Temperature Range (Note 3) ... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
NUMBER
TOP VIEW
*DNC
IN
1
2
3
4
8
7
6
5
DNC*
DNC*
OUT
LTC1798CS8
LTC1798CS8-2.5
LTC1798CS8-3
LTC1798CS8-4.1
LTC1798CS8-5
**DNC/FB
GND
DNC*
S8 PACKAGE
8-LEAD PLASTIC SO
S8 PART MARKING
TJMAX = 125°C, θJA = 190°C/W
1798
* CONNECTED INTERNALLY. DO NOT
CONNECT EXTERNAL CIRCUITRY TO
THESE PINS
** DNC FOR LTC1798-2.5/LTC1798-3/
LTC1798-4.1/LTC1798-5, FB FOR LTC1798
179825
17983
179841
17985
Consult factory for parts specified with wider operating temperature range.
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AVAILABLE OPTIO S
PACKAGE TYPE
SO-8 (S8)
OUTPUT
VOLTAGE
(V)
TEMPERATURE
RANGE
TEMPERATURE
COEFFICIENT
(ppm/°C)
ACCURACY
(%)
(°C)
ORDER NUMBER
LTC1798CS8-2.5
LTC1798CS8-3
LTC1798CS8-4.1
LTC1798CS8-5
LTC1798CS8
PART MARKING
179825
17983
2.5
0 to 70
0 to 70
0 to 70
0 to 70
0 to 70
0.15
0.15
0.15
0.15
0.4
40
40
40
40
40
3
4.096
5
179841
17985
Adjustable
1798
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full specified temperature range, otherwise specifications are at TA = 25°C.
VIN = VOUT(NOMINAL) + 0.2V, IOUT = 0mA unless otherwise noted. FB = OUT for the LTC1798.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Input Voltage Range
Input Current
●
●
12.6
V
IN
I
FB = OUT for LTC1798
4.0
6.5
8.5
µA
µA
IN
V
Output Voltage (Note 4)
LTC1798, FB = OUT
LTC1798 ADJ
LTC1798-2.5
LTC1798-3
LTC1798-4.1
2.3755
– 0.4
2.4963
2.9955
4.090
2.385
2.3945
0.4
2.5037
3.0045
4.102
5.0075
0.15
V
%
V
V
V
OUT
2.5
3
4.096
5
LTC1798-5
LTC1798 All Fixed Options
4.9925
–0.15
V
%
2
LTC1798 Series
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full specified temperature range, otherwise specifications are at TA = 25°C.
VIN = VOUT(NOMINAL) + 0.2V, IOUT = 0mA unless otherwise noted. FB = OUT for the LTC1798.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
8
MAX
UNITS
ppm
e
Output Voltage Noise (Note 5)
Output Voltage Temp Coefficient (Note 6)
Line Regulation
0.1Hz ≤ f ≤ 10Hz
n
P-P
TC
T
≤ T ≤ T
●
●
●
15
40
120
0.3
ppm/°C
ppm/V
mV/mA
MIN
J
MAX
V
V
/V
V
= (V
IN
+ 0.2V) to 12.6V
30
OUT IN
OUT(NOMINAL)
/I
Load Regulation (Note 7)
Sourcing 0mA to 10mA
Sinking 0mA to 2mA
0.1
1.75
OUT OUT
4.0
6.5
mV/mA
mV/mA
●
I
Short-Circuit Output Current
Dropout Voltage (Note 8)
Output Hysteresis (Note 9)
FB Pin Input Current
V
V
Shorted to GND
20
2
40
4
mA
mA
SC
OUT
OUT
Shorted to V
IN
∆V
I
I
= 0, ∆V ≤ 0.1%
OUT
●
●
100
200
mV
mV
DO
OUT
OUT
= 10mA, ∆V
≤ 0.1%
OUT
V
∆T = –40°C to 85°C
∆T = 0°C to 70°C
200
50
ppm
ppm
HYST
I
LTC1798, OUT = FB
10
nA
FB
Note 6: Temperature coefficient is the change in output voltage divided by
the nominal output voltage divided by the specified temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 7: Load regulation is measured on a pulse basis from no load to the
specified load current. Output changes due to die temperature change
must be taken into account separately.
Note 2: The LTC1798 is guaranteed functional over the operating
temperature range of –40°C to 100°C.
Note 3: If the part is stored outside of the specified operating temperature
Note 8: Dropout voltage is (V – V ) when V falls to 0.1% below its
range, the output may shift due to hysteresis.
IN
OUT
OUT
nominal value at V = V
+ 0.5V.
IN
OUT
Note 4: ESD (Electostatic Discharge) sensitive device. Extensive use of
ESD protection devices are used internal to the LTC1798, 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 filter
at 0.1Hz and 2-pole lowpass filter at 10Hz.
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.
U W
TYPICAL PERFOR A CE CHARACTERISTICS
LTC1798-2.5* Dropout Voltage
vs Output Source Current
LTC1798-2.5*
Input Current vs Temperature
LTC1798 Series Output Short-
Circuit Current vs Temperature
100
90
80
70
60
50
40
30
20
10
0
8
7
6
5
4
3
2
1
0
70
60
50
40
30
20
10
5
V
= 2.7V
T
V
= 25°C
A
OUTPUT
SHORTED
TO GND
T
A
= 25°C
IN
= V
+ 0.2V
IN
OUT(NOM)
OUTPUT
SHORTED
TO V
IN
0
0
0.1
1
10
100
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
1798 G02
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
1798 G03
OUTPUT SOURCE CURRENT (mA)
1798 G01
*Similar performance characteristics can be expected for all voltage options.
3
LTC1798 Series
U W
TYPICAL PERFOR A CE CHARACTERISTICS
LTC1798-2.5* Output Short-Circuit
Current vs Input Voltage
LTC1798-2.5* Output Short-Circuit
Current vs Input Voltage
LTC1798 Series
Load Regulation
25
20
15
10
5
42
5
4
T = 25°C
A
T
= 25°C
A
V
= V
+ 0.2V
OUTPUT SHORTED
IN
OUT(NOM)
TO V
3
IN
SINKING
2
1
SOURCING
0
–1
–2
–3
–4
–5
T
= 25°C
A
OUTPUT SHORTED
TO GND
0
41
2
6
8
10
12
14
2
6
8
10
12
14
0
0.1
1
10
100
4
4
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
1798 G06
1258-G04
1798 G05
LTC1798-2.5*
Output Voltage vs Input Voltage
LTC1798-2.5*
Input Current vs Input Voltage
LTC1798-2.5 PSRR vs Frequency
2.5010
2.5005
2.5000
2.4995
7
60
50
40
30
20
10
0
T
= 25°C
T
= 25°C
A
V
IN
= 2.7V
A
6
5
4
2
6
8
10
12
14
2
6
8
10
12
14
4
4
10
100
1k
10k
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
FREQUENCY (Hz)
1798 G09
1798 G07
1798 G08
LTC1798-5 Input Current vs Input
Voltage in Dropout
LTC1798-2.5 Input Current vs Input
Voltage in Dropout
LTC1798-2.5 0.1Hz to 10Hz Noise
1400
1200
1000
800
600
400
200
0
250
200
150
100
50
V
IN
= 2.7V
T
= –55°C
A
T
T
= 25°C
A
T
T
= 25°C
A
A
T
= 125°C
A
= 125°C
A
5µV/DIV
= –55°C
0
1SEC/DIV
0
1
2
3
4
5
6
7
8
9
10
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
1798 G10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1798 G11
1798 G12
4
LTC1798 Series
U
U
U
PI FU CTIO S
DNC (Pins 1, 5, 7, 8): Do Not Connect. Connected
internally for post package trim. These pins must be left
unconnected.
R1+ R2
VOUT = 2.385V
;
R1 is connected from OUT
R2
to FB and R2 from FB to GND. Selecting R2 ≥ 10k will
make IOUT < 250µA.
IN (Pin 2): Positive Supply. Bypassing with a 0.1µF
capacitor is recommended if the output loading changes.
(VOUT + 0.2V) ≤ VIN ≤ 12.6V.
GND (Pin 4): Negative Supply or Ground Connection.
OUT (Pin 6): Reference Output. The output can source up
to10mAandsinkupto2mA.Itisstablewithoutputbypass
capacitor ranging from 0µF to 1µF.
DNC (Pin 3): (LTC1798-2.5/LTC1798-3/LTC1798-4.1/
LTC1798-5) Do Not Connect. Connected internally for
post package trim. This pin must be left unconnected.
FB (Pin 3): (LTC1798) Resistor Divider Feedback Pin.
ConnectaresistordividerfromOUTtoGNDandthecenter
tap to FB. This pin sets the output potential.
W
BLOCK DIAGRA
2
IN
+
OUT
R1
6
–
2.385V
FB 3 (LTC1798)
R2
GND
4
1798 BD
NOTE: R1 AND R2 ARE NOT CONNECTED FOR LTC1798
5
LTC1798 Series
U
W
U U
APPLICATIO S I FOR ATIO
Longer Battery Life
capacitance is required, a resistor in series with the
capacitor 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.
Series references have an advantage over shunt style
references. Tooperate, shuntreferencesrequirearesistor
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
beingcontrolledisnotoperatingatthismaximumcurrent,
the shunt reference must always sink this current, result-
ing in high power dissipation and short battery life.
LTC1798-5
5.2V
2
6
IN
5V
TO
OUT
C
12.6V
OUT
TheLTC1798serieslowdropoutreferencesdonotrequire
a current setting resistor and can operate with any supply
voltage from (VOUT(NOMINAL) + 0.2V) to 12.6V. When the
circuitry being regulated does not demand current, the
LTC1798 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 LTC1798-2.5, yet the same connection can deliver
10mA of load current when demanded.
>1µF
GND
4
0.1µF
DAMPING RESISTOR
<1k
1798 F02
Figure 2. Adding a Damping Resistor with
Output Capacitors Greater Than 1µF
10k
1k
Output Bypass Capacitor
The LTC1798 series is designed to be stable with or
without capacitive loads. With no capacitive load, the
referenceisidealforfastsettlingapplications,orwherePC
board space is at a premium.
100
10
In applications with significant 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
1
10
100
1000
OUTPUT CAPACITOR VALUE (µF)
1798 F03
Figure 3. Damping Resistance vs Output Capacitor Value
1mA
IOUT
1mA
IOUT
0mA
0mA
VOUT
100mV/DIV
VOUT
100mV/DIV
10ms/DIV
0.5ms/DIV
1798 F01a
1798 F01b
Figure 1. Reference Output Load Transient Response, 1µF Output Capacitor
6
LTC1798 Series
U
W U U
APPLICATIO S I FOR ATIO
Internal P-Channel Pass Transistor
These references consume only 4µA of quiescent current
underlightandheavyloadsaswellasindropout;whereas,
PNP-based references waste considerable amounts of
current when the pass transistor is saturated. In addition,
the LTC1798 series provides a lower dropout voltage
(200mV max) than PNP-based references.
TheLTC1798seriesfeaturesaninternalP-channelMOSFET
pass transistor. This provides several advantages over
similar designs using a PNP bipolar pass transistor.
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
7
5
8
6
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
3
4
2
0.010 – 0.020
(0.254 – 0.508)
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
SO8 1298
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
7
LTC1798 Series
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TYPICAL APPLICATIO S
Micropower Low Dropout Negative Reference
Supply Splitter
0.2V ≤ V ≤ 8.5V
CC
2
IN
LTC1798-2.5
2.5V
VIRTUAL
GROUND
6
2
6
V
= 5V
IN
OUT
OUT LTC1798-3
CC
0.1µF
0.1µF
8
0.1µF
GND
4
2
3
GND
4
–
1
1798 TA04
V
OUT
= –3V
1/2 LTC1542
+
1798 TA03
4
V
SS
= –4V
Low Power, Low Voltage Supply Reference for LTC1096L
1µF
MPU
1
2
3
4
8
7
6
5
CS/
V
CC
SHDN
SERIAL DATA LINK
(MICROWIRETM AND
SPI COMPATIBLE)
+IN
ANALOG INPUT
0V TO 3V RANGE
CLK
LTC1096L
–IN
D
OUT
SERIAL DATA LINK
GND
V
REF
6
OUT
V
IN
4
2
GND
IN
3.2V TO
12.6V
0.1µF
LTC1798-3
1798 TA05
MICROWIRE is a trademark of National Semiconductor Corporation.
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT®1389
Nanopower Precision Shunt Voltage Reference
800nA Quiescent Current, 0.05% Max, 10ppm/°C Max Drift
1.25V and 2.5V Versions, SO-8 Package
LT1634
LT1460
LT1461
LT1790
Micropower Precision Shunt Voltage Reference
Micropower Series Reference
0.05% Max, 25ppm/°C Max Drift, 1.25V, 2.5V, 4.096V and 5V Outputs
0.075% Max, 10ppm/°C Max Drift, 2.5V, 5V and 10V Outputs
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Micropower Precision Series Voltage Reference
SOT-23, LDO Precision Micropower Reference
1798fa LT/LCG 1100 2K REV A • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1999
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
8
●
●
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
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