LINEAR TECHNOLOGY LTC1798 Technical data

FEATURES

TEMPERATURE (°C)

–40 –20 0 20 40 60 80 100

REFERENCE VOLTAGE CHANGE (mV)

1798 TA02

4

3

2

1

–2

–1

–3

–4

0

LTC1798 Series

Micropower Low

Dropout References

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DESCRIPTIO

■

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

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APPLICATIO S

■

Battery-Powered Systems

■

Handheld Instruments

■

Precision Power Supplies

■

A/D and D/A Converters

The LTC®1798/LTC1798-2.5/LTC1798-3/LTC1798-4.1/
LTC1798-5 are micropower bandgap references that com­bine high accuracy and low drift with very low supply
current and small package size. The combination of ultralow
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.

This series of references uses curvature compensation to
obtain low temperature coefficient and trimmed thin-film
resistors to achieve high output accuracy. These refer­ences 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
stable with capacitance up to 1µF. This feature is important
in critical applications where PC board space is a premium
and fast settling is demanded.

The LTC1798 series references provided power dissipa­tion advantages over shunt references. In addition to
supply current, shunt references must also idle the entire
load current to operate.

TYPICAL APPLICATIO

2.5V Battery-Powered Reference

2.7V

TO 12.6V

0.1µF

2

IN

LTC1798-2.5

GND

4

OUT

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The LTC1798 series is available in the SO-8 package.

, LTC and LT are registered trademarks of Linear Technology Corporation.

LTC1798-2.5 Temperature Drift

6

2.5V

1798 TA01

1

LTC1798 Series

1

2

3

4

8

7

6

5

TOP VIEW

DNC*
DNC*
OUT
DNC*

*DNC

IN

**DNC/FB

GND

S8 PACKAGE

8-LEAD PLASTIC SO

WW

W

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ABSOLUTE AXI U RATI GS

(Note 1)

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

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AVAILABLE OPTIO S

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PACKAGE/ORDER I FOR ATIO

ORDER PART

NUMBER

LTC1798CS8
LTC1798CS8-2.5
LTC1798CS8-3
LTC1798CS8-4.1
LTC1798CS8-5

T

= 125°C, θJA = 190°C/W

JMAX

* 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

Consult factory for parts specified with wider operating temperature range.

S8 PART MARKING

1798
179825
17983
179841
17985

OUTPUT TEMPERATURE TEMPERATURE

VOLTAGE RANGE ACCURACY COEFFICIENT

(V) (°C) (%) (ppm/°C) ORDER NUMBER PART MARKING

2.5 0 to 70 0.15 40 LTC1798CS8-2.5 179825
3 0 to 70 0.15 40 LTC1798CS8-3 17983

4.096 0 to 70 0.15 40 LTC1798CS8-4.1 179841
5 0 to 70 0.15 40 LTC1798CS8-5 17985

Adjustable 0 to 70 0.4 40 LTC1798CS8 1798

PACKAGE TYPE

SO-8 (S8)

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full specified temperature range, otherwise specifications are at TA = 25°C.
VIN = V

OUT(NOMINAL)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IN

I

IN

V

OUT

2

+ 0.2V, I

Input Voltage Range ● 12.6 V
Input Current FB = OUT for LTC1798 4.0 6.5 µA

Output Voltage (Note 4) LTC1798, FB = OUT 2.3755 2.385 2.3945 V

= 0mA unless otherwise noted. FB = OUT for the LTC1798.

OUT

LTC1798 ADJ – 0.4 0.4 %
LTC1798-2.5 2.4963 2.5 2.5037 V
LTC1798-3 2.9955 3 3.0045 V
LTC1798-4.1 4.090 4.096 4.102 V
LTC1798-5 4.9925 5 5.0075 V
LTC1798 All Fixed Options –0.15 0.15 %

● 8.5 µA

LTC1798 Series

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full specified temperature range, otherwise specifications are at TA = 25°C.
VIN = V

OUT(NOMINAL)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

e

n

TC Output Voltage Temp Coefficient (Note 6) T
V

OUT/VIN

V

OUT/IOUT

I

SC

∆V

DO

V

HYST

I

FB

+ 0.2V, I

Output Voltage Noise (Note 5) 0.1Hz ≤ f ≤ 10Hz 8 ppm

Line Regulation VIN = (V

= 0mA unless otherwise noted. FB = OUT for the LTC1798.

OUT

≤ TJ ≤ T

MIN

MAX

OUT(NOMINAL)

+ 0.2V) to 12.6V ● 30 120 ppm/V

P-P

● 15 40 ppm/°C

Load Regulation (Note 7) Sourcing 0mA to 10mA ● 0.1 0.3 mV/mA

Sinking 0mA to 2mA 1.75 4.0 mV/mA

● 6.5 mV/mA

Short-Circuit Output Current V

Dropout Voltage (Note 8) I

Shorted to GND 20 40 mA

OUT

Shorted to V

V

OUT

= 0, ∆V

OUT

= 10mA, ∆V

I

OUT

IN

≤ 0.1% ● 100 mV

OUT

≤ 0.1% ● 200 mV

OUT

24 mA

Output Hysteresis (Note 9) ∆T = –40°C to 85°C 200 ppm

∆T = 0°C to 70°C 50 ppm

FB Pin Input Current LTC1798, OUT = FB 10 nA

Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.

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
range, the output may shift due to hysteresis.

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 6: Temperature coefficient is the change in output voltage divided by
the nominal output voltage divided by the specified temperature range.

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 8: Dropout voltage is (V
nominal value at V

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.

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TYPICAL PERFOR A CE CHARACTERISTICS

LTC1798-2.5* Dropout Voltage
vs Output Source Current

100

TA = 25°C

90
80
70
60
50
40
30

DROPOUT VOLTAGE (mV)

20
10

0

0 1 10 100

*Similar performance characteristics can be expected for all voltage options.

0.1

OUTPUT SOURCE CURRENT (mA)

1798 G01

LTC1798-2.5*
Input Current vs Temperature

8

VIN = 2.7V

7

6

5

4

3

INPUT CURRENT (µA)

2

1

0

–50 –25

025

50 75

TEMPERATURE (°C)

100 125

1798 G02

IN

150

– V

) when V

OUT

= V

OUT

IN

+ 0.5V.

LTC1798 Series Output Short­Circuit Current vs Temperature

70

TA = 25°C
V

= V

60

IN

OUT(NOM)

50

40

30

20

10

5

OUTPUT SHORT-CIRCUIT CURRENT (mA)

0

–50 –25

025

falls to 0.1% below its

OUT

+ 0.2V

50 75

TEMPERATURE (°C)

OUTPUT
SHORTED
TO GND

OUTPUT
SHORTED
TO V

100 125

IN

1798 G03

150

3