LT1790ACS6-2.5#TRM [Linear]
LT1790 - Micropower SOT-23 Low Dropout Reference Family; Package: SOT; Pins: 6; Temperature Range: 0°C to 70°C;
| 型号： | LT1790ACS6-2.5#TRM |
| 厂家： | 
Linear |
| 描述： | LT1790 - Micropower SOT-23 Low Dropout Reference Family; Package: SOT; Pins: 6; Temperature Range: 0°C to 70°C 电源电路 参考电压源 光电二极管 |
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Final Electrical Specifications
LT1790-2.5
2.5V Micropower SOT-23
Low Dropout Reference
March 2000
U
FEATURES
DESCRIPTIO
The LT®1790-2.5 is a SOT-23 micropower low dropout
seriesreferencethatcombineshighaccuracyandlowdrift
with low power dissipation and small package size. This
micropower reference uses curvature compensation to
obtain a low temperature coefficient and trimmed preci-
sionthin-filmresistorstoachievehighoutputaccuracy. In
addition, the LT1790-2.5 uses post-package trimming to
greatly reduce the temperature coefficient and increase
theoutputaccuracy.Outputaccuracyisfurtherassuredby
excellent line and load regulation. Special care has been
taken to minimize thermally induced hysteresis.
■
High Accuracy:
A Grade—0.05% Max
B Grade—0.1% Max
Low Drift:
A Grade—10ppm/
B Grade—25ppm/
Low Supply Current: 60µA Max
Sinks and Sources: 5mA Min
Low Dropout Voltage
■
°
C Max
°C Max
■
■
■
■
■
Guaranteed Operational –40°C to 125°C
Wide Supply Range: 2.6V to 18V
The LT1790-2.5 is ideally suited for battery-operated
systems because of its small size, low supply current and
reduced dropout voltage. This reference provides supply
current and power dissipation advantages over shunt
referencesthatmustidletheentireloadcurrenttooperate.
However, since the LT1790-2.5 can also sink current, it
can operate as a micropower negative voltage reference
with the same performance as a positive reference.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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APPLICATIO S
■
Handheld Instruments
■
Negative Voltage References
■
Industrial Control Systems
■
Data Acquisition Systems
■
Battery-Operated Equipment
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TYPICAL APPLICATIO
Typical VOUT Distribution
50
167 UNITS
45
40
LT1790BC LIMITS
Positive Connection
35
LT1790AC LIMITS
30
25
20
15
10
5
4
6
V
= 2.5V
LT1790-2.5
1, 2
2.6V ≤ V ≤ 18V
IN
OUT
0.1µF
1µF
1790 TA01
0
2.498
2.499 2.500
2.501
2.502
OUTPUT VOLTAGE (V)
1790 TA02
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.
1
LT1790-2.5
W W
U W
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ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
Input Voltage .......................................................... 20V
Specified Temperature Range..................... 0°C to 70°C
Operating Temperature Range
(Note 2) ........................................... –40°C to 125°C
Storage Temperature Range
ORDER PART
NUMBER
TOP VIEW
GND 1
GND 2
6 V
OUT
LT1790ACS6-2.5
LT1790BCS6-2.5
5 DNC*
DNC* 3
4 V
IN
(Note 3) ........................................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
S6 PACKAGE
6-LEAD PLASTIC SOT-23
S6 PART MARKING
T
= 150°C, θ = 230°C/W
JA
JMAX
LTMX
LTMZ
*DNC: DO NOT CONNECT
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications that apply over the specified temperature
range, otherwise specifications are at TA = 25°C. VIN = 3V, CL = 1µF unless otherwise specified.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Output Voltage (Notes 3, 4)
LT1790ACS6-2.5
2.49875
–0.05
2.50
2.50125
0.05
V
%
LT1790BCS6-2.5
2.4975
–0.1
2.50
2.5025
0.1
V
%
Output Voltage Temperature Coefficient (Note 5)
Line Regulation
LT1790ACS6-2.5
LT1790BCS6-2.5
●
●
5
12
10
25
ppm/°C
ppm/°C
3V ≤ V ≤ 18V
50
170
220
ppm/V
ppm/V
IN
●
●
Load Regulation (Note 6)
I
I
I
Source = 5mA
Source = 5mA
Sink = 5mA
80
70
160
250
110
ppm/mA
ppm/mA
ppm/mA
OUT
OUT
OUT
Dropout Voltage (Note 7)
V
– V , ∆V
≤ 0.1%
OUT
IN
OUT
I
I
I
= 0mA
●
●
60
300
40
100
400
250
mV
mV
mV
OUT
OUT
OUT
Source = 5mA
Sink = 5mA
Supply Current
V
OUT
= 2.5V
35
60
75
µA
µA
●
Minimum Current
Turn-On Time
V
C
= –2.5V
100
700
125
µA
µs
OUT
= 1µF
LOAD
Output Noise (Note 8)
0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
12
33
µV
P-P
µV
RMS
Long-Term Drift of Output Voltage (Note 9)
Hysteresis (Note 10)
50
ppm/√kHr
∆T = 0°C to 70°C
∆T = –40°C to 85°C
●
●
40
60
ppm
ppm
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: The LT1790S6 is guaranteed functional over the operating
temperature range of –40°C to 125°C.
Note 4: ESD (Electrostatic Discharge) sensitive device. Extensive use of
ESD protection devices are used internal to the LT1790, however, high
electrostatic discharge can damage or degrade the device. Use proper ESD
handling precautions.
Note 3: If the part is stored outside of the specified temperature range, the
output voltage may shift due to hysteresis.
2
LT1790-2.5
ELECTRICAL CHARACTERISTICS
Note 5: Temperature coefficient is measured by dividing the change in
output voltage by the specified temperature range. Incremental slope is
also measured at 25°C.
Note 9: Long-term drift typically has a logarithmic characteristic and
therefore changes after 1000 hours tend to be smaller than before that
time. Total drift in the second thousand hours is normally less than one
third that to the first thousand hours with a continuing trend toward
reduced drift with time. Long-term drift is affected by differential stress
between the IC and the board material created during board assembly. See
Applications Information.
Note 6: 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 7: Excludes load regulation errors.
Note 10: Hysteresis in the 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 to 85°C or –40°C before a successive measurements. Hysteresis is
roughly proportional to the square of the temperature change. Hysteresis
is not normally a problem for operational temperature excursions where
the instrument might be stored at high or low temperature. See
Applications Information.
Note 8: Peak-to-peak noise is measured with a single pole highpass filter
at 0.1Hz and a 2-pole lowpass filter at 10Hz. The unit is enclosed in a still
air environment to eliminate thermocouple effects on the leads. The test
time is 10 seconds. RMS noise is measured with a single pole highpass
filter at 10Hz and a 2-pole lowpass filter at 1kHz. The resulting output is
full-wave rectified and then integrated for a fixed period, making the final
reading an average as opposed to RMS. A correction factor of 1.1 is used
to convert from average to RMS and a second correction of 0.88 is used to
correct for the nonideal bandpass of the filters.
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TYPICAL PERFOR A CE CHARACTERISTICS
Minimum Input-Output Voltage
Differential (Sourcing) Series Mode
Minimum Input-Output Voltage
Differential (Sinking) Series Mode
Output Voltage Temperature Drift
10
90
70
2.508
2.506
2.504
2.502
2.500
2.498
2.496
2.494
FOUR TYPICAL PARTS
T
A
= –55°C
T = 125°C
A
50
T
= 25°C
A
1
30
10
100µA
1mA
5mA
–10
–30
0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
50
TEMPERATURE (°C)
90
130
–50 –30 –10 10
50 70 90 110 130
–50 –30 –10 10
110
30
30
70
INPUT-OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
1790 G14
1790 G13
1790 G15
Load Regulation (Sinking)
Load Regulation (Sourcing)
Supply Current vs Input Voltage
5
4
3
2
1
0
0
–1
–2
–3
–4
–5
80
70
60
50
40
30
20
10
0
T
= –55°C
A
T
= 25°C
A
T
= –55°C
A
A
T
= 125°C
A
T
= 25°C
T
= –55°C
A
T
= 125°C
A
T
= 125°C
A
T
= 25°C
A
10
0.1
1
10
0.1
1
0
10
20
5
15
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
INPUT VOLTAGE (V)
1790 617
1790 616
1790 G18
3
LT1790-2.5
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TYPICAL PERFOR A CE CHARACTERISTICS
Power Supply Rejection Ratio
vs Frequency
Line Regulation
Output Impedance vs Frequency
2.515
2.510
2.505
2.500
2.495
2.490
1000
100
10
20
10
C
L
= 1µF
T
= 125°C
A
C
L
= 0.47µF
0
C
L
= 1µF
–10
–20
–30
–40
–50
–60
–70
–80
T
= 25°C
A
C
L
= 4.7µF
T
= –55°C
A
2.489
1
0
2
4
6
8
10 12 14 16 18 20
100
1k
10k
100k
100
1k
10k
100k
1M
FREQUENCY (Hz)
INPUT VOLTAGE (V)
FREQUENCY (Hz)
1790 G21
1790 G20
1790 G19
Long-Term Drift
(Data Points Reduced After 500 Hr)
–2.5V Characteristics
140
120
100
80
0.30
0.25
0.20
0.15
0.10
0.05
0
R1 10k
3V
4
LT1790-2.5
1, 2
6
V
OUT
R
L
5k
1µF
60
–V
EE
40
20
0
T
T
T
= 25°C
= 125°C
= –55°C
A
A
A
–20
–40
–60
0
200
400
600
800
1000
–4.0 –3.5 –3.0 –2.5 –2.0 –1.5 –1.0 –0.5
OUTPUT TO GROUND VOLTAGE (V)
0
HOURS
1790 G22
1790 G23
Output Noise 0.1Hz to 10Hz
Output Voltage Noise Spectrum
10
8
C
L
= 1µF
6
I
O
= 0µA
I
O
= 100µA
4
I
= 250µA
O
2
I
O
= 1mA
1k
0
10
100
10k
0
1
2
3
4
5
6
7
8
9
10
FREQUENCY (Hz)
TIME (SEC)
1790 G25
1790 G24
4
LT1790-2.5
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APPLICATIONS INFORMATION
Bypass and Load Capacitors
The test circuit of Figure 3 is used to measure the stability
of various load currents. With RL = 1k, the 1V step
produces a current step of 1mA. Figure 4 shows the
response to a ±0.5mA load. Figure 5 is the output re-
sponse to a sourcing step from 4mA to 5mA, and Figure
6 is the output response of a sinking step from –4mA to
–5mA.
The LT1790-2.5 voltage reference should have an input
bypass capacitor of 0.1µF or larger, however the bypass-
ing of other local devices may serve as the required
component.Thisreferencealsorequiresanoutputcapaci-
tor for stability. The optimum output capacitance for most
applications is 1µF, although larger values work as well.
This capacitor affects the turn-on and settling time for the
output to reach its final value.
1k
4
6
V
IN
LT1790-2.5
1, 2
3V
C
C
L
1µF
IN
V
1V
GEN
Figure 1 shows the turn-on time for the LT1790-2.5 with
a 1µF input bypass and 1µF load capacitor. Figure 2 shows
the output response to a 0.5V transient on VIN with the
same capacitors.
0.1µF
1790 F03
Figure 3. Response Time Test Circuit
VGEN
3V
VIN
VOUT
3V
2V
2V
1V
0V
VOUT
1790 F04
1790 F01
Figure 4. LT1790-2.5 Sourcing and Sinking 0.5mA
Figure 1. Turn-On Characteristics of LT1790-2.5
VIN
3V
2V
1V
0V
VOUT
VOUT
VGEN
–2V
–3V
1790 F05
1790 F02
Figure 5. LT1790-2.5 Sourcing 4mA to 5mA
Figure 2. Output Response to 0.5V Ripple on VIN
5
LT1790-2.5
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APPLICATIONS INFORMATION
VGEN
8V
transistor from turning on and driving the grounded
output. C1 provides stability during load transients. This
connectionmaintainstheaccuracyandtemperaturecoef-
ficient of the positive connected LT1790-2.5.
6V
Long-Term Drift
4V
2V
0V
VOUT
Long-term drift cannot be extrapolated from acceler-
ated high temperature testing. This erroneous tech-
niquegivesdriftnumbersthatarewidelyoptimistic.The
only way long-term drift can be determined is to mea-
sure it over the time interval of interest. The LT1790S6
drift data was taken on over 100 parts that were soldered
into PC boards similar to a “real world” application. The
boards were then placed into a constant temperature oven
with TA = 30°C, their outputs scanned regularly and
measured with an 8.5 digit DVM. Long-term drift curves
are shown in the Typical Performance Characteristics.
1790 F06
Figure 6. LT1790-2.5 Sinking –4mA to –5mA
Positive or Negative Operation
Series operation is ideal for extending battery life. If the
LT1790-2.5 is operated in series mode it does not require
an external current setting resistor. The specifications
guarantee the LT1790-2.5 operates from 2.6V to 18V.
When the circuitry being regulated does not demand
current, the series connected LT1790-2.5 consumes only
a few hundred µW, yet the same connection can sink or
source 5mA of load current when demanded. A typical
series connection is shown on the front page of this data
sheet.
Hysteresis
Hysteresis data shown in Figures 8 and 9 represent the
worst-case data taken on parts from 0°C to 70°C and from
–40°Cto85°C. Unitswerecycledseveraltimesoverthese
temperature ranges and the largest change is shown. As
expected, the parts cycled over the higher temperature
range have higher hysteresis than those cycled over the
lower range.
The circuit in Figure 7 shows the connection for a –2.5V
reference. The LT1790-2.5 can be used as a very stable
negative reference, however, it requires a positive voltage
applied to Pin 4 to bias internal circuitry. This voltage
must be current limited with R1 to keep the output PNP
When the LT1790-2.5 is IR reflow soldered onto a PC
board, the output shift is typically just 150ppm (0.015%).
R1
10k
3V
4
6
C1
0.1µF
LT1790-2.5
1, 2
V
OUT
= –2.5V
V
– 2.5V
125µA
C
EE
L
R
=
L
1µF
V
EE
1790 F07
Figure 7. Using the LT1790-2.5 to Build a –2.5V Reference
6
LT1790-2.5
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APPLICATIONS INFORMATION
12
11
10
9
16
14
12
10
8
85°C TO 25°C
–40°C TO 25°C
70°C TO 25°C
0°C TO 25°C
7
8
6
4
2
0
6
5
4
3
2
1
0
–50
–30
–10
10
30
50
70
90
110
130
–100 –80 –60 –40 –20
0
20
40
60
80 100 120
HYSTERESIS (ppm)
HYSTERESIS (ppm)
1790 F08
1790 F09
Figure 8. Worst-Case 0°C to 70°C Hysteresis on 44 Units
Figure 9. Worst-Case –40°C to 85°C Hysteresis on 44 Units
W
W
SI PLIFIED SCHEMATIC
V
V
4
6
IN
OUT
GND
1, 2
1790 SS
7
LT1790-2.5
TYPICAL APPLICATION
U
–2.5V Negative 50mA Series Reference
No Load Supply Current
I
CC = 1.6mA
IEE = 440µA
V
= 5V
CC
2k
4
6
LT1790-2.5
1, 2
V
= 5.1V
Z
5.1k
–2.5V
50mA
V
= –5V
EE
MPS2907A
1µF
1790 TA03
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PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
S6 Package
6-Lead Plastic SOT-23
(LTC DWG # 05-08-1634)
2.6 – 3.0
(0.110 – 0.118)
2.80 – 3.00
1.50 – 1.75
(0.059 – 0.069)
(0.110 – 0.118)
(NOTE 3)
0.00 – 0.15
(0.00 – 0.006)
0.90 – 1.45
(0.035 – 0.057)
0.35 – 0.55
(0.014 – 0.022)
PIN 1
1.90
(0.074)
REF
0.35 – 0.50
(0.014 – 0.020)
SIX PLACES (NOTE 2)
0.90 – 1.30
(0.035 – 0.051)
0.09 – 0.20
(0.004 – 0.008)
(NOTE 2)
0.95
(0.037)
REF
NOTE:
S6 SOT-23 0898
1. DIMENSIONS ARE IN MILLIMETERS
2. DIMENSIONS ARE INCLUSIVE OF PLATING
3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
4. MOLD FLASH SHALL NOT EXCEED 0.254mm
5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ)
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179025i LT/TP 0300 4K • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 2000
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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