Linear Technology LT1175 Datasheet

LT1 1 75

500mA Negative

Low Dropout Micropower

FEATURES

■

Stable with Wide Range of Output Capacitors

■

Operating Current: 45µA

■

Shutdown Current: 10µA

■

Adjustable Current Limit

■

Positive or Negative Shutdown Logic

■

Low Voltage Linear Dropout Characteristics

■

Fixed 5V and Adjustable Versions

■

Tolerates Reverse Output Voltage

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APPLICATIO S

■

Analog Systems

■

Modems

■

Instrumentation

■

A/D and D/A Converters

■

Interface Drivers

■

Battery-Powered Systems

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

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Regulator

DESCRIPTIO

The LT®1175 is a negative micropower low dropout regu­lator. It features 45µA quiescent current, dropping to
10µA in shutdown. A new reference amplifier topology
gives precision DC characteristics along with the ability to
maintain good loop stability with an extremely wide range
of output capacitors. Very low dropout voltage and high
efficiency are obtained with a unique power transistor anti­saturation design. Adjustable and fixed 5V versions are
available.

Several new features make the LT1175 very user-friendly.
The SHDN pin can interface directly to either positive or
negative logic levels. Current limit is user-selectable at
200mA, 400mA, 600mA and 800mA. The output can be
forced to reverse voltage without damage or latchup.
Unlike some earlier designs, the increase in quiescent
current during a dropout condition is actively limited.

The LT1175 has complete blowout protection with current
limiting, power limiting and thermal shutdown. Special
attention was given to the problem of high temperature
operation with micropower operating currents,
output voltage rise under no-load conditions. The LT1175
is available in 8-pin PDIP and SO packages, 3-lead SOT­223 as well as 5-pin surface mount DD and through-hole
TO-220 packages. The 8-pin SO package is specially
constructed for low thermal resistance.

preventing

TYPICAL APPLICATIO

Typical LT1175 Connection

+ +

CIN*

SHDN GND

–V

IN

*C

IS NEEDED ONLY IF REGULATOR IS MORE THAN 6" FROM

IN

INPUT SUPPLY CAPACITOR. SEE APPLICATIONS INFORMATION
SECTION FOR DETAILS

INPUT
I

LIM2

I

LIM4

LT1175-5

SENSE

OUT

U

C

OUT

≥ 0.1µF

–5V
UP TO 500mA

1175 TA01

Minimum Input-to-Output Voltage

1.0
TJ = 25°C

, I

I

LIM2

0.8

0.6

0.4

0.2

INPUT-TO-OUTPUT VOLTAGE (V)

0

0

TIED TO V

LIM4

0.2

0.1
OUTPUT CURRENT (A)

0.3

IN

0.4

0.5

0.6

0.7

1175 TA02

1

LT1 1 75

1

2

3

FRONT VIEW

TAB IS

INPUT

GND

V

IN

OUTPUT

ST PACKAGE

3-LEAD PLASTIC SOT-223

WW

W

ABSOLUTE MAXIMUM RATINGS

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(Note 1)

Input Voltage (Transient 1 sec, Note 11) ................ 25V

Input Voltage (Continuous) .................................... 20V

Input-to-Output Differential Voltage (Note 12)........ 20V

5V SENSE Pin (with Respect to GND Pin) ...... 2V, –10V

ADJ SENSE Pin

(with Respect to OUTPUT Pin) ................ 20V, –0.5V

5V SENSE Pin

(with Respect to OUTPUT Pin) .................. 20V, –7V

Output Reverse Voltage ............................................ 2V

SHDN Pin to GND Pin Voltage (Note 2) ..... 13.5V, –20V

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PACKAGE/ORDER INFORMATION

TOP VIEW

V

1

IN

I

2

LIM2

OUTPUT

3

SENSE

4

N8 PACKAGE
8-LEAD PDIP

θJA = 80°C/W TO 120°C/W DEPENDING

ON PC BOARD LAYOUT

V

8

IN

I

7

LIM4

SHDN

6

GND

5

ORDER

PART NUMBER

LT1175CN8
LT1175CN8-5
LT1175IN8
LT1175IN8-5

INPUT

FRONT VIEW

5

TAB

IS

θJA = 27°C/W TO 60°C/W DEPENDING

ON PC MOUNTING. SEE DATA SHEET
FOR DETAILS

4
3
2
1

Q PACKAGE

5-LEAD PLASTIC DD

SHDN Pin to VIN Pin Voltage .......................... 30V, –5V

Operating Junction Temperature Range

LT1175C..............................................0°C to 125°C

LT1175I.......................................... –40°C to 125°C

Ambient Operating Temperature Range

LT1175C................................................0°C to 70°C

LT1175I............................................ –40°C to 85°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec)..................300°C

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ORDER

SHDN
GND
INPUT
SENSE
OUTPUT

PART NUMBER

LT1175CQ
LT1175CQ-5
LT1175IQ
LT1175IQ-5

θJA = 50°C/W WITH BACKPLANE

AND 10cm2 TOPSIDE LAND
SOLDERED TO TAB

PART NUMBER

LT1175CST-5
LT1175IST-5

ORDER

TOP VIEW

1

V

IN

I

2

LIM2

OUTPUT

3

SENSE

4

S8 PACKAGE

8-LEAD PLASTIC SO

θJA = 60°C/W TO 100°C/W DEPENDING

ON PC BOARD LAYOUT

8

V
I

7

LIM4

SHDN

6

GND

5

PINS 1, 8 ARE INTERNALLY
CONNECTED TO DIE
ATTACH PADDLE FOR HEAT

IN

SINKING. ELECTRICAL
CONTACT CAN BE MADE TO
EITHER PIN. FOR BEST
THERMAL RESISTANCE,
PINS 1, 8 SHOULD BE
CONNECTED TO AN
EXPANDED LAND THAT IS
OVER AN INTERNAL OR
BACKSIDE PLANE.
SEE APPLICATIONS
INFORMATION

ORDER

PART NUMBER

LT1175CS8
LT1175CS8-5
LT1175IS8
LT1175IS8-5

S8 PART MARKING
1175

11755

1175I
1175I5

FRONT VIEW

5
4
3
2

TAB IS
INPUT

5-LEAD PLASTIC TO-220

θJA = 50°C/W, θJC = 5°C/W

1

T PACKAGE

SHDN
GND
INPUT
SENSE
OUTPUT

ORDER

PART NUMBER

LT1175CT
LT1175CT-5
LT1175IT
LT1175IT-5

Consult factory for Military grade parts.

ELECTRICAL CHARACTERISTICS

range, otherwise specifications are at TA = 25°C. V

OUT

The ● denotes specifications which apply over the operating temperature

= 5V, VIN = 7V, I

OUT

= 0, V

SHDN

= 3V, I

LIM2

and I

tied to VIN, TJ = 25°C,

LIM4

unless otherwise noted. To avoid confusion with “min” and “max” as applied to negative voltages, all voltages are shown as
absolute values except where polarity is not obvious.

PARAMETER CONDITIONS MIN TYP MAX UNITS

Feedback Sense Voltage Adjustable Part 3.743 3.8 3.857 V

Fixed 5V Part 4.93 5.0 5.075 V

Output Voltage Initial Accuracy Adjustable, Measured at 3.8V Sense 0.5 1.5 %

Fixed 5V 0.5 1.5 %

Output Voltage Accuracy (All Conditions) VIN – V

P = 0 to P

Quiescent Input Supply Current VIN – V

2

= 1V to VIN = 20V, I

OUT

, TJ = T

MAX

≤ 12V 45 65 µA

OUT

MIN

to T

= 0A to 500mA ● 1.5 2.5 %

OUT

(Note 3)

MAX

● 80 µA

LT1 1 75

ELECTRICAL CHARACTERISTICS

range, otherwise specifications are at TA = 25°C. V

OUT

The ● denotes specifications which apply over the operating temperature

= 5V, VIN = 7V, I

OUT

= 0, V

SHDN

= 3V, I

LIM2

and I

tied to VIN, TJ = 25°C,

LIM4

unless otherwise noted. To avoid confusion with “min” and “max” as applied to negative voltages, all voltages are shown as
absolute values except where polarity is not obvious.

PARAMETER CONDITIONS MIN TYP MAX UNITS

GND Pin Current Increase with Load (Note 4) ● 10 20 µA/mA
Input Supply Current in Shutdown V

Shutdown Thresholds (Note 9) Either Polarity On SHDN Pin ● 0.8 2.5 V
SHDN Pin Current (Note 2) V

Output Bleed Current in Shutdown (Note 6) V

SENSE Pin Input Current (Adjustable Part Only, Current Flows Out of Pin) ● 75 150 nA

Dropout Voltage (Note 7) I

Current Limit (Note 11) VIN – V

Line Regulation (Note 10) VIN – V
Load Regulation (Note 5, 10) I
Thermal Regulation P = 0 to P

Output Voltage Temperature Drift TJ = 25°C to T
Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.
Note 2: SHDN pin maximum positive voltage is 30V with respect to

and 13.5V with respect to GND. Maximum negative voltage is –20V

–V

IN

with respect to GND and –5V with respect to –V
Note 3: P

= 1.5W for 8-pin packages, and 6W for 5-pin packages. This

MAX

power level holds only for input-to-output voltages up to 12V, beyond
which internal power limiting may reduce power. See Guaranteed Current
Limit curve in Typical Performance Characteristics section. Note that all
conditions must be met.

Note 4: GND pin current increases because of power transistor base drive.
At low input-to-output voltages (< 1V) where the power transistor is in
saturation, GND pin current will be slightly higher. See Typical
Performance Characteristics.

Note 5: With I

= 0, at TJ > 125°C, power transistor leakage could

LOAD

increase higher than the 10µA to 25µA drawn by the output divider or fixed
voltage SENSE pin, causing the output to rise above the regulated value.
To prevent this condition, an internal active pull-up will automatically turn
on, but supply current will increase.

Note 6: This is the current required to pull the output voltage to within 1V
of ground during shutdown.

Note 7: Dropout voltage is measured by setting the input voltage equal to
the normal regulated output voltage and measuring the difference between

= 0V 10 20 µA

SHDN

= 0V to 10V (Flows Into Pin) ● 48 µA

SHDN

V

= –15V to 0V (Flows Into Pin) 1 4 µA

SHDN

= 0V, VIN = 15V 0.1 1 µA

OUT

● 25 µA

● 15 µA

(Fixed Voltage Only, Current Flows Out of Pin) ● 12 20 µA

= 25mA ● 0.1 0.2 V

OUT

= 100mA ● 0.18 0.26 V

I

OUT

= 500mA ● 0.5 0.7 V

I

OUT

Open, I

I

LIM2

I

Open, I

LIM4

I

, I

LIM2

LIM4

Open ● 390 600 975 mA

I

LIM2

Open ● 260 400 650 mA

I

LIM4

I

, I

LIM2

LIM4

= 0mA to 500mA ● 0.1 0.35 %

OUT

= 300mA ● 0.33 0.5 V

OUT

= 200mA ● 0.3 0.45 V

OUT

Open, I

= 1V to 12V ● 520 800 1300 mA

OUT

= 100mA ● 0.26 0.45 V

OUT

Open ● 130 200 325 mA

= 1V to VIN = 20V ● 0.003 0.015 %/V

OUT

(Notes 3, 8) 5-Pin Packages 0.04 0.1 %/W

MAX

8-Pin Packages 0.1 0.2 %/W

, or 25°C to T

JMIN

JMAX

VIN and V

. For currents between 100mA and 500mA, with both I

OUT

0.25 1.25 %

LIM

pins tied to VIN, maximum dropout can be calculated from

= 0.15 + 1.1Ω (I

V

DO

OUT

).

Note 8: Thermal regulation is a change in the output voltage caused by die

.

IN

temperature gradients, so it is proportional to chip power dissipation.
Temperature gradients reach final value in less than 100ms. Output
voltage changes after 100ms are due to absolute die temperature changes
and reference voltage temperature coefficient.

Note 9: The lower limit of 0.8V is guaranteed to keep the regulator in
shutdown. The upper limit of 2.5V is guaranteed to keep the regulator
active. Either polarity may be used, referenced to GND pin.

Note 10: Load and line regulation are measured on a pulse basis with
pulse width of 20ms or less to keep chip temperature constant. DC
regulation will be affected by thermal regulation (Note 8) and chip
temperature changes. Load regulation specification also holds for currents

or I

up to the specified current limit when I

LIM2

are left open.

LIM4

Note 11: Current limit is reduced for input-to-output voltage above 12V.
See the graph in Typical Performance Characteristics for guaranteed limits
above 12V.

Note 12: Operating at very large input-to-output differential voltages
(>15V) with load currents less than 5mA requires an output capacitor with
an ESR greater than 1Ω to prevent low level output oscillations.

3

LT1 1 75

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TYPICAL PERFORMANCE CHARACTERISTICS

Typical Current Limit
Characteristics

1.0
CURRENT LIMIT CHANGES ONLY SLIGHTLY

WITH TEMPERATURE SO CURVES ARE
REPRESENTATIVE OF ALL TEMPERATURES

0.8

I

, I

TIED TO V

LIM2

0.6

0.4

CURRENT (A)

0.2

I

I

I

LIM2

LIM2

LIM4

LIM

TIED TO V

TIED TO V

, I

LIM4

IN

IN

IN

OPEN

Guaranteed Current Limit

0.6
I

, I

TIED TO V

LIM2

I

LIM4

I

LIM2

I

LIM2

LIM

TIED TO V

TIED TO V

, I

OPEN

LIM4

IN

IN

0.5

0.4

0.3

CURRENT (A)

0.2

0.1

IN

CURVES REPRE­SENT MINIMUM
GUARANTEED
LIMITS AT ALL
TEMPERATURES

Output Voltage Temperature Drift

5.05
OUTPUT

FIXED 5V PART

5.00

4.95

3.84

VOLTAGE (V)

FEEDBACK VOLTAGE

ADJUSTABLE PART

3.80

0

5

0
INPUT-TO-OUTPUT DIFFERENTIAL VOLTAGE (V)

15

10

Minimum Input-to-Output Voltage

1.0
TJ = 25°C

REDUCED

V

IN

UNTIL OUTPUT

0.8
VOLTAGE

DROPS 1%

0.6

I

, I

LIM2

LIM4

OPEN

0.4

0.2

INPUT-TO-OUTPUT VOLTAGE (V)

0

0

0.2

0.1
OUTPUT CURRENT (A)

I

, I

LIM2

LIM4

TIED TO V

0.3

I

LIM2

IN

TO V

0.4

TIED

IN

0.5

Shutdown Input Current

25

20

15

10

INPUT CURRENT (µA)

5

0

0

TJ = 125°C

5

10

INPUT VOLTAGE (V)

TJ = –55°C

15

20

I

LIM4

TO V

0.6

TJ = 25°C

20

TIED

IN

1175 G01

1175 G04

1175 G07

0.7

0

5101520

25

0

INPUT-TO-OUTPUT DIFFERENTIAL VOLTAGE (V)

25

1175 G02

3.76
–50

0

–25

JUNCTION TEMPERATURE (°C)

50

25

75

100

125

1175 G03

SENSE Bias Current

Minimum Input-to-Output Voltage

1.0
VIN REDUCED UNTIL OUTPUT
VOLTAGE DROPS 1%.

, I

I

0.8

0.6

0.4

0.2

INPUT-TO-OUTPUT VOLTAGE (V)

0

0

TIED TO V

LIM2

LIM4

0.2

0.1
OUTPUT CURRENT (A)

IN

TJ = 125°C

TJ = –55°C

0.3

0.4

0.5

TJ = 25°C

0.6

1175 G05

0.7

Shutdown Thresholds

2.5

2.0

1.5

1.0

THRESHOLD (V)

0.5
DEVICE IS OFF
BELOW THRESHOLD

25

0

–50

POSITIVE THRESHOLD

NEGATIVE THRESHOLD

0

–25

TEMPERATURE (°C)

5025

100

125

1175 G08

75

(Adjustable Part)

100

80

60

40

CURRENT (nA)

20

0

–50

0

–25

TEMPERATURE (°C)

25

SHDN Pin Characteristics

15

VIN = 25V
CHARACTERISTICS DO NOT
CHANGE SIGNIFICANTLY WITH

10

TEMPERATURE, SO A SINGLE
CURVE IS SHOWN. POSITIVE
CURRENT FLOWS INTO
SHDN PIN

5

0

PIN CURRENT (µA)

–10

IF SHDN PIN IS NEGATIVE WITH
RESPECT TO INPUT VOLTAGE AND

–5

INPUT VOLTAGE IS LESS THAN 15V,
NEGATIVE BREAKOVER POINT WILL
BE ABOUT 8V BELOW –V

–15

–25 –20 –10 0

SHUTDOWN TO GROUND VOLTAGE (V)

–5 10 20

50

75

IN

5

125

100

1175 G06

15

25

1175 G09

4