Linear Technology LT1635 Datasheet

FEATURES

■

Guaranteed Operation at 1.2V

■

Op Amp and Reference on Single Chip

■

Micropower: 130µA Supply Current

■

Industrial Temperature Range SO-8 Packages

■

Rail-to-Rail Output

■

High Output Current: 25mA Min

■

Output Drives 1000pF

■

Capable of Floating Mode Operation

■

Specified for 5V and ±5V Supplies

■

Low Reference Drift: 30ppm/°C

■

Industry Standard LM10 Pinout

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APPLICATIONS

■

Battery- or Solar-Powered Systems

Portable Instrumentation
Sensor Conditioning

■

Precision Current Regulators

■

Precision Voltage Regulators

■

Battery Level Indicator

■

Thermocouple Transmitter

LT1635

Micropower Rail-to-Rail

Op Amp and Reference

U

DESCRIPTION

The LT®1635 is a new analog building block that includes a
rail-to-rail output op amp, a precision reference and reference
buffer. The device operates from supplies as low as a single

1.2V or up to ± 5V, yet it consumes only 130µA of supply
current.

The input common mode range of the op amp includes
ground and incorporates phase reversal protection to pre­vent false outputs from occurring when the input is below
the negative supply. The rail-to-rail output stage can swing to
within 15mV of each rail with no load and can swing to within
250mV of each rail while delivering 10mA of output current.
The gain bandwidth of the op amp is 175kHz and it is unity­gain stable with up to 1000pF load capacitance.

The 0.2V reference is referred to V– and includes a buffer
amplifier to enhance flexibility. The reference and buffer
combine to achieve a drift of 30ppm/°C, a line regulation of
20ppm/V and a load regulation of 150ppm/mA.

The LT1635 is available in 8-pin PDIP and SO packages, and
has the industry standard LM10 pinout.

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

TYPICAL APPLICATION

0V to 5V Regulator

C1

0.01µF

V

> 5.2V

IN

–

7

2

LT1635

+

3

1



R3
5k

6

4

8

1635 TA01

R2

3.9k

V

100k

OUT

ADJ

R1

U



V

OUT

0V TO 5V

Typical Distribution of Input Offset Voltage

25

VS = 5V, 0V

= 25°C

T

A

20

15

10

PERCENT OF UNITS

5

0

–1.0

–0.6

INPUT OFFSET VOLTAGE (mV)

–0.2

0.2

0.6

1.0

1635 TA02

1

LT1635

WW

W

ABSOLUTE MAXIMUM RATINGS

Total Supply Voltage (V+ to V–) .............................. 14V

Input Differential Voltage ......................................... 14V

Input Current ...................................................... ±25mA

Output Short-Circuit Duration .......................Continuous

Operating Temperature Range

(Note 1) .............................................. –40°C to 85°C

Junction Temperature........................................... 150°C

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

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

U

U

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PACKAGE/ORDER INFORMATION



ORDER PART

NUMBER

LT1635CN8
LT1635CS8
LT1635IN8
LT1635IS8

S8 PART

MARKING

REFOUT
OP AMP IN (–)
OP AMP IN (+)

N8 PACKAGE
8-LEAD PDIP

T

JMAX

T

JMAX

TOP VIEW

1
2
3

–

4

V

= 150°C, θJA = 130°C/ W (N8)
= 150°C, θJA = 190°C/ W (S8)

–
+

–

+

+

S8 PACKAGE

8-LEAD PLASTIC SO

REF FB

8

+

V

7

OP AMP OUT

6

BALANCE

5



U

1635 1635I

Consult factory for Military grade parts.

ELECTRICAL CHARACTERISTICS

5V OP AMP: V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OS

VOS ADJ Offset Voltage Adjust Range Positive Adjust ● 6 8 mV

I

OS

I

B

e

n

i

n

R

IN

CMRR Common Mode Rejection Ratio VCM = 0V to 4V 92 110 dB

A

VOL

V

OL

V

OH

= 5V, 0V; VCM = V

S

Input Offset Voltage 0.3 1.3 mV

Input Offset Voltage Drift –40°C ≤ TA ≤ 85°C (Note 3) ● 3.0 7.0 µV/°C

Input Offset Current ● 0.2 0.6 nA
Input Bias Current 2.0 4.0 nA

Input Noise Voltage 0.1Hz to 10Hz 1 µV
Input Noise Voltage Density f = 1kHz 50 nV/√Hz
Input Noise Current Density f = 1kHz 0.05 pA/√Hz
Input Resistance Differential ● 725 MΩ

Input Voltage Range ● 04V

Large-Signal Voltage Gain VO = 200mV to 4.5V, No Load ● 100 450 V/mV

Shunt Gain I

Output Voltage Swing Low VS = 5V, No Load ● 210 mV

Output Voltage Swing High VS = 5V, No Load ● 4.975 4.985 V

= 2.5V, TA = 25°C, unless otherwise noted. (Note 1)

OUT

0°C ≤ TA ≤ 70°C ● 0.5 1.6 mV
–40°C ≤ T

Negative Adjust

Common Mode, VCM = 0V to 4V 6 GΩ

V

O

V

O

OUT

V

O

(Note 4) ● 8 20 V/mV

V

S

V

S

V

S

V

S

≤ 85°C ● 1.8 mV

A

= 200mV to 4.5V, RL = 1.1k ● 45 200 V/mV
= 200mV to 4.5V, RL = 500Ω ● 35 150 V/mV

= 0.1mA to 5mA V/mV

= 1.5V to 6.45V 15 25 V/mV

= 5V, I
= 5V, I

= 5V, I
= 5V, I

= 5mA ● 125 250 mV

SINK

= 10mA ● 200 500 mV

SINK

= 5mA ● 4.65 4.8 V

SOURCE

= 10mA ● 4.55 4.75 V

SOURCE

● –1.4 – 2 mV

● 2.5 5.0 nA

P-P

● 85 97 dB

2

ELECTRICAL CHARACTERISTICS

LT1635

5V OP AMP: V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I

SC

PSRR Power Supply Rejection Ratio VS = 1.2V to 12V, VCM = VO = 0.2V 93 100 dB

I

S

GBW Gain Bandwidth Product f = 1kHz 175 kHz
SR Slew Rate AV = –1, R

5V REFERENCE: V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

REF

TC V

REF

= 5V, 0V; VCM = V

S

Short-Circuit Current VS = 5V, Short to GND ● 25 40 mA

Minimum Operating Supply Voltage (Note 2) ● 1.1 1.2 V
Supply Current 130 200 µA

= 5V, 0V; TA = 25°C, unless otherwise noted. (Note 1)

S

Feedback Sense Voltage Voltage at Pin 1 with Pin 1 Connected ● 189 200 211 mV

Reference Drift (Note 3) ● 30 100 ppm/°C
Feedback Current Current into Pin 8 3.5 10 nA

Line Regulation 0 ≤ I

Load Regulation I

Reference Amplifier Gain VO = 0.2V to 3.5V 45 90 V/mV

= 2.5V, TA = 25°C, unless otherwise noted. (Note 1)

OUT

= 5V, Short to V

V

S

to Pin 8 (Note 5)

≤ 1mA, V

REF

= 1.2V to 5V 20 35 ppm/V

V

S

= 1.3V to 5V (Note 2) ● 30 55 ppm/ V

V

S

= 0 to 1mA 150 300 ppm/mA

REF

CC

= ∞ 0.045 V/µs

L

= 200mV

REF

● 25 40 mA

● 90 97 dB

● 150 260 µA

● 5.0 15 nA

● 200 500 ppm/mA

● 25 50 V/mV

±5V OP AMP: V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OS

VOS ADJ Offset Voltage Adjust Range Positive Adjust ● 6 8 mV

I

OS

I

B

e

n

i

n

R

IN

CMRR Common Mode Rejection Ratio VCM = –5V to 4V 94 115 dB

= ±5V; VCM = V

S

Input Offset Voltage 0.3 1.5 mV

Input Offset Voltage Drift 0°C ≤ TA ≤ 85°C (Note 3) ● 4.5 10.0 µV/°C

Input Offset Current ● 0.2 0.6 nA
Input Bias Current 2.0 4 nA

Input Noise Voltage 0.1Hz to 10Hz 1 µV
Input Noise Voltage Density f = 1kHz 50 nV/√Hz
Input Noise Current Density f = 1kHz 0.05 pA/√Hz
Input Resistance Differential ● 735 MΩ

Input Voltage Range ● –5 4 V

= 0V, TA = 25°C, unless otherwise noted. (Note 1)

OUT

≤ 70°C ● 0.5 1.9 mV

0°C ≤ T

A

–40°C ≤ TA ≤ 85°C ● 2.1 mV

Negative Adjust ● –1.4 –2 mV

Common Mode, V

= –5V to 4V 9 GΩ

CM

● 2.5 5 nA

P-P

● 91 110 dB

3

LT1635

ELECTRICAL CHARACTERISTICS

±5V OP AMP: V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

A

VOL

V

O

I

SC

PSRR Power Supply Rejection Ratio VS = ±1V to ±6V, VCM = VO = 0V 90 100 dB

I

S

GBW Gain Bandwidth Product f = 1kHz 175 kHz
SR Slew Rate AV = –1, R

±5V REFERENCE: V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

REF

TC V

REF

= ±5V; VCM = V

S

Large-Signal Voltage Gain VO = –4.5V to 4.5V, No Load ● 175 300 V/mV

Output Voltage Swing VS = ±5V, No Load ● ±4.975 ±4.985 mV

Short-Circuit Current VS = ±5V ±25 ±40 mA

Supply Current 135 215 µA

= ±5V, TA = 25°C, unless otherwise noted. (Note 1)

S

Feedback Sense Voltage Voltage at Pin 1 with Pin 1 Connected ● 189 200 211 mV

Reference Drift (Note 3) ● 40 120 ppm/°C
Feedback Current Current into Pin 8 3.5 10 nA

Line Regulation 0 ≤ I

Load Regulation I

Reference Amplifier Gain VO = 0.2V to 8.5V 45 90 V/mV

= 0V, TA = 25°C, unless otherwise noted. (Note 1)

OUT

V

= –4.5V to 4.5V, RL = 1.1k ● 15 100 V/mV

O

V

= –4.5V to 4.5V, RL = 500Ω ● 10 60 V/mV

O

V

= ±5V, I

S

V

= ±5V, I

S

to Pin 8 (Note 5)

REF

V

= ±0.6V to ±5V 20 25 ppm /V

S

= ±0.65V to ±5V (Note 2) ● 30 55 ppm/V

V

S

= 0 to 1mA 150 300 ppm/mA

REF

VS = 10V, 0V ● 25 50 V/mV

= 5mA ● ±4.65 ±4.75 mV

SINK

= 10mA ● ±4.5 ±4.6 mV

SINK

= ∞ 0.05 V/µs

L

≤ 1mA, V

= 200mV

REF

● 88 98 dB

● 160 280 µA

● 5.0 15 nA

● 200 500 ppm/mA

The ● denotes specifications that apply over the full operating temperature
range.

Note 1: The LT1635C is guaranteed to operate over the commercial
temperature range of 0°C to 70°C. It is designed, characterized and
expected to meet these extended temperature limits, but is not tested at
–40°C and 85°C. The LT1635I is guaranteed to meet the industrial
temperature range.

Note 2: The LT1635 op amp operates on a 1.2V supply over the full
industrial temperature range with an input common mode of 0V to 0.2V.
The minimum supply voltage for the reference to operate properly over
this temperature range is 1.3V.

4

Note 3: This parameter is not 100% tested. Temperature coefficient is
measured by dividing the change in output voltage by specified
temperature range.

Note 4: Shunt gain defines the operation in floating applications when the
output is connected to the V
referred to V

Note 5: If part is stored outside of the specified temperature range, the
output may shift due to hysteresis.

–

.

+

terminal and input common mode is

UW

COMMON MODE VOLTAGE (V)

–1

INPUT BIAS CURRENT (nA)

–2

–1

0

3

1635 G03

–3

–4

–5

0

1

2

4

TA = 125°C

VS = 5V, 0V

TA = 25°C

TA = –55°C

TIME AFTER POWER ON (MINUTES)

0

0

CHANGE IN OFFSET VOLTAGE (µV)

20

60

80

100

140

1

5

7

1635 G09

40

120

4

9

10

2

3

68

V

S

= ±5V

T

A

= 25°C

TYPICAL PERFORMANCE CHARACTERISTICS

LT1635

Op Amp

Supply Current vs Supply Voltage

220

200

180

160

140

120

SUPPLY CURRENT (µA)

100

80

60

TA = –55°C

= 25°C

T

A

T

= 125°C

A

6

2

3

4

5

SUPPLY VOLTAGE (V)

7

0.1Hz to 10Hz Noise Voltage

VS = ±5V

= 25°C

T

A

Input Bias and Offset Currents
vs Temperature

100

I

50

0

OFFSET CURRENT (pA)BIAS CURRENT (nA)

–1

–2

10

8

9

1635 G01

–3

–50

–25

OS

I

B

25

0

TEMPERATURE (°C)

50

VS = 5V, 0V

75

100

125

1635 G02

Input Bias Current
vs Common Mode Voltage

Noise Voltage Density
vs Frequency

80

VS = ±2.5V

= 25°C

T

A

70

60

Input Noise Current vs Frequency

0.5
VS = ±2.5V

= 25°C

T

A

0.4

0.3

NOISE VOLTAGE (1µV/DIV)

0

Typical Distribution of Offset
Voltage Drift with Temperature

25

VS = 5V, 0V

20

15

10

PERCENT OF UNITS

5

0

–6

1

–4

2

6

5

4

3

TIME (SEC)

–2 0 2

TCVOS (µV/°C)

7

89

10

1635 G04

46

1635 G07

50

40

INPUT NOISE VOLTAGE DENSITY (nV/√Hz)

30

1

10 100 1000

FREQUENCY (Hz)

Minimum Supply Voltage

200

0

–200

–400

–600

–800

CHANGE IN INPUT OFFSET VOLTAGE (V)

–1000

0

TA = 125°C

= 25°C

T

A

T

= –55°C

A

TOTAL SUPPLY VOLTAGE (V)

12

1635 G05

1635 G08

0.2

0.1

INPUT NOISE CURRENT DENSITY (pA/√Hz)

0

1

10 100 1000

FREQUENCY (Hz)

Turn-On Drift
of Three Typical Units

1635 G06

5

LT1635

UW

TYPICAL PERFORMANCE CHARACTERISTICS

Op Amp

Voltage Gain vs Frequency Capacitive Load Handling

120

100

80

60

40

VOLTAGE GAIN (dB)

20

0

–20

0.1 100k

0.01

1 100

10 1k 1M

FREQUENCY (Hz)

VS = ±2.5V

= 25°C

T

A

10k

1635 G10

Gain Phase vs Frequency

60

50

40

30

20

10

0

VOLTAGE GAIN (dB)

–10

–20

–30

10

PHASE

MARGIN

70°

FREQUENCY (kHz)

VS = ±2.5V

= 25°C

T

A

PHASE

GAIN

100 1000

1635 G11

100

120

140

PHASE SHIFT (DEG)

160

180

200

220

240

260

280

60

VS = ±5V

=

∞

R

L

TA = 25°C

50

40

30

OVERSHOOT (%)

20

10

0

10

AV = 5

= 10 AV = 1

A

V

100 1000 10000

CAPACITIVE LOAD (pF)

Gain-Bandwidth Product and

Slew Rate vs Temperature

0.10

0.09

0.08

0.07

0.06

SLEW RATE (V/µs)

0.05

RISING

SLEW RATE

FALLING
SLEW RATE

VS = ±5V

Phase Margin vs Temperature

350

300

250

200

GAIN-BANDWIDTH

150

GAIN-BANDWIDTH PRODUCT (kHz)

PRODUCT

PHASE MARGIN

VS = ±2.5V

75

70

PHASE MARGIN (DEG)

65

60

55

Voltage Gain vs Load Resistance

1M

VS = 5V, 0V

TA = –55°C

VOLTAGE GAIN (V/V)

1635 G12

TA = 25°C

TA = 125°C

0.04
–50

–25 0

25 75

TEMPERATURE (°C)

Shunt Gain

0.5
T

= 25°C

A

0.4

0.3

0.2

0.1

INPUT VOLTAGE CHANGE (mV)

0

0

13

+

V

IN

–

2

OUTPUT VOLTAGE (V)

50 100 125

I

= 20mA

OUT

V

I

OUT

I

= 1mA

OUT

7

5

6

4

1635 G13

+

OUT

–

1635 G16

100

8

–50 –25

0

TEMPERATURE (°C)

50

25

75

100

1635 G14

Large-Signal Transient Response
VS = ±5V

2V/DIV

1635 G17

A

= 1, NO LOAD

V

INPUT 8V

200µs/DIV

P-P

125

50

100k

0.1

LOAD RESISTANCE TO GROUND (kΩ)

10 1001 1000

1635 G15

Large-Signal Transient Response
VS = 5V, 0V

0V

1V/DIV

A

= 1, NO LOAD

V

INPUT PULSE 0V TO 4V

100µs/DIV

0V

1635 G18

6

UW

SOURCING LOAD CURRENT (mA)

0.001

0.01

OUTPUT SATURATION VOLTAGE (V)

0.1

1

0.10.01 101

1635 G21

VS = ±2.5V
V

OD

= 30mV

TA = 125°C

TA = –55°C

TA = 25°C

FREQUENCY (Hz)

0.1

0

POWER SUPPLY REJECTION RATIO (dB)

20

40

60

80

120

1

10 100 1k

1635 G24

10k 100k

100

VS = ±2.5V
T

A

= 25°C

POSITIVE
SUPPLY

NEGATIVE

SUPPLY

TYPICAL PERFORMANCE CHARACTERISTICS

LT1635

Op Amp

Output Saturation Voltage
vs Input Overdrive

16

14

12

10

8

6

4

2

OUTPUT SATURATION VOLTAGE (mV)

0

510 20

0

INPUT OVERDRIVE (mV)

V

= ±2.5V, NO LOAD

S

= 25°C

T

A

OUTPUT HIGH

OUTPUT LOW

15

Common Mode Range
vs Temperature

+

V

V+ – 0.5

+

V

– 1

Output Saturation Voltage
vs Load Current (Output Low)

1000

VS = ±2.5V

= 30mV

V

OD

100

10

OUTPUT SATURATION VOLTAGE (mV)

25

30

1635 G19

1

0.001 0.1 1 10

0.01

SINKING LOAD CURRENT (mA)

T

= 125°C

A

TA = 25°C

TA = –55°C

1635 G20

Common Mode Rejection Ratio
vs Frequency

120

100

80

VS = ±2.5V

= 25°C

T

A

Output Saturation Voltage
vs Load Current (Output High)

Power Supply Rejection Ratio
vs Frequency

–

V

COMMON MODE RANGE (V)

–

V

– 0.5

–

V

– 1

–50

–25 0

Output Impedance vs Frequency

10000

VS = ±2.5V

= 25°C

T

A

AV = 100

1000

AV = 10 AV = 1

100

10

OUTPUT IMPEDANCE (Ω)

1

0.1 1
FREQUENCY (kHz)

50 100 125

25 75

TEMPERATURE (°C)

10 100 1000

1635 G22

1635 G25

60

40

20

COMMON MODE REJECTION RATIO (dB)

0

1

10 100 1k 10k

FREQUENCY (Hz)

Small-Signal Transient Response
VS = ±5V

10mV/DIV

A

V

C

L

= 1
= 15pF

50µs/DIV

1635 G26

1635 G23

100k

0V

Small-Signal Transient Response
VS = 5V, 0V

10mV/DIV

A

= 1

V

C

= 15pF

L

INPUT 50mV TO 100mV

50µs/DIV

1635 G27

7

LT1635

FREQUENCY (Hz)

1

GAIN (dB)

100

1k

1635 G33

40

0

10 100 10k

–20

–40

120

80

60

20

100k 1M 10M

VS = 5V, 0V
T

A

= 25°C

UW

TYPICAL PERFORMANCE CHARACTERISTICS

Typical Distribution
of Initial Accuracy

20

VS = 5V, 0V

18

= 25°C

T

A

16
14
12

10

8

PERCENT OF UNITS

6
4
2
0

194

196

REFERENCE VOLTAGE (mV)

198

200 202

204

206

1635 G28

Line Regulation

208

VS = 5V, 0V

207

206

205

204

203

202

REFERENCE OUTPUT (mV)

201

200

0

TA = –55°C

TA = 125°C

24 8

SUPPLY VOLTAGE (V)

TA = 25°C

6

10 12 14

Reference

1635 G29

Load Regulation

200

VS = 5V, 0V

= 25°C

T

A

0

–200

–400

REFERENCE CHANGE (ppm)

–600

0

1

SOURCING CURRENT (mA)

2

3

4

1635 G30

Reference Output vs Temperature
of Two Typical Units

205

VS = ±5V



204



203



202

REFERENCE OUTPUT (mV)



201

–50

050

–25 25 75 125

TEMPERATURE (°C)

BLOCK DIAGRA

100

W

1635 G31

2

3

BALANCE

5

–

OP AMPINPUTS

+

Output Saturation
vs Load Current (Sourcing)

1.5
VS = 5V, 0V

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

OUTPUT SATURATION VOLTAGE (V)

0.6

0.5

0

= –55°C

T

A

1

SOURCING CURRENT (mA)

REFERENCE

OUTPUT

FEEDBACK

6

200mV

REFERENCE

TA = 125°C

8

+

TA = 25°C

2

–

REF AMP

+

1635 G32

V

7

4

V

Reference Amplifier Gain

3

+

1

REFERENCE
OUTPUT

–

1635 BD

8

LT1635

–

+

LT1635

OP AMP

5V

99R

(a) (b)

1mV

100mV

R

–

+

5V

1mV

1635 F02

OUTPUT
SATURATED
≈2mV

LT1635

OP AMP

U

WUU

APPLICATIONS INFORMATION

The LT1635 is fully specified with V+ = 5V, V– = 0V and
VCM = 2.5V. The op amp offset voltage is internally
trimmed to a minimum value at these supply voltages. A
unique feature of this device is that it operates from a
single 1.2V supply up to ±5V. A full set of specifications is
provided at ±5V supply voltages. The positive supply pin
of the LT1635 should be bypassed with a small capacitor
(about 0.1µF), as well as the negative supply pin when
using split supplies.

Op Amp

The LT1635 is fully specified for single supply operation,
i.e., when the negative supply is 0V. Input common mode
range of the op amp includes ground and the output
swings within a few millivolts of ground while sinking
current. The input stage of the op amp incorporates phase
reversal protection to prevent false outputs from occur­ring when the input is below the negative supply. Protec­tive resistors have been included in the input leads so that
current does not become excessive when the inputs are
forced below the negative supply.

The op amp also includes an offset nulling feature, this is
accomplished by connecting the BALANCE pin (Pin 5) to
a variable voltage derived from the reference output. The
offset adjust range is asymmetrical, typically –2mV to
8mV. At room temperature the input offset voltage of the
LT1635 is within the null range, thus the offset voltage can
be adjusted to zero. Figure 1 shows the standard offset
adjustment.

+

V

–

2

3

Figure 1. Standard Offset Adjustment

Output

The output voltage swing of the LT1635 is a function of
input overdrive as shown in the typical performance curves.
When monitoring voltages within 15mV of either rail, gain

LT1635

+

5

1

8

4

R1
10k

6

V

REF

–

V

1635 F01

should be taken to keep the output from saturating. For
example, a 1mV input signal will cause the amplifier to set
up in its linear region in the gain 100 configuration as
shown in Figure 2a. However, 1mV is not enough to make
the amplifier function properly in the voltage follower mode
(Figure 2b).

Figure 2. Gain 100 Amplifier and Voltage Follower

Distortion

There are two main contributors of distortion in op amps:
distortion caused by nonlinear common mode rejection
and output crossover distortion as the output transitions
from sourcing to sinking current. The common mode
rejection ratio of the LT1635 is very good, typically 110dB.
Therefore, as long as the input operates in normal com­mon mode range, there will be very little common mode
induced distortion. Crossover distortion will increase as
the output load resistance decreases. For the lowest dis­tortion, the LT1635 should be operated with the output
always sourcing current.

Reference

The reference of the LT1635 consists of a 200mV precision
bandgap and a reference amplifier. As shown in the block
diagram, the 0.2V precision bandgap is referred to V– and
is internally connected to the noninverting input of the ref­erence amplifier. This configuration offers great flexibility
in that the reference voltage can be amplified or the reference
amplifier can be used as a comparator. Unlike the op amp,
the output of the reference amplifier can only swing within

0.8V (typ) of the positive rail. To guarantee that the reference
amplifier does not saturate over the industrial temperature
range, the minimum operating supply should be 1.3V. The
reference amplifier can source 2mA of load current and can
sink 10µ A over the industrial temperature range.

9

LT1635

1

3

1635 TA08

2D1

8

4

7

6

+

–

LED DIMS BELOW 7V

R2
12k

R3

680k

R1
680k

R4

1.5k

–

+

LT1635

U

TYPICAL APPLICATIONS

Low Voltage Regulator

C1

0.01µF

V

R1

28k

R2
2k

*USE ELECTROLYTIC 
OUTPUT CAPACITORS

>3.2V

IN

2

–

7

LT1635

3

+

8

1

6

4



V

OUT

3V

+

OPTIONAL*

1635 TA03

Best Regulation

2

–

LT1635

3

+

R2

48k

2-Terminal Current Regulator Shunt Regulator

+

(R2 + R3)V

I

=

OUT

(R1)(R3)

2

–

7

LT1635

3

+

R1

R2

8

6

4

1

R3

–

1635 TA05

REF



C1*

0.01µF

R2

2

–

LT1635

3

R1

*REQUIRED FOR CAPACITIVE LOADING

+

8

> 6V

V

IN

7

6

V

OUT

4

8

1

R1
2k

7

6

4

1

5V

1635 TA04

+

=V

V

OUT

R2

1 +

REF

()

R1

–

1635 TA06

10

R2

49.9k
1%

2

3

Q1

2N3904

Negative Regulator 6V Battery-Level Indicator

GROUND

+

C1

–

LT1635

+

7

6

4

8

1

R1

2k

1%

47µF
ELECT

V

OUT

–5V

V

IN

≤ –5.5V

1635 TA07

SI PLIFIED

R1

6k

2

R2

INPUTS

6k

3

300k

5

BALANCE

WW

SCHEMATICS

Q1

Q2

Q4

Q3

Q5

LT1635

Op Amp

+

V

7

Q21

Q28

C2

Q15

Q13

Q7

Q6

Q14

Q16

+

C1

Q20

Q17 Q18

Q19

Q26

Q24

Q27

1635 SSOA

Q25

6

4

OUTPUT

–

V

+

7

V

–

V

4

PACKAGE DESCRIPTION

0.300 – 0.325

(7.620 – 8.255)

Reference

REF FB

8 REFOUT

×16

×1

1635 SSREF

1

U

Dimensions in inches (millimeters) unless otherwise noted.

N8 Package

8-Lead PDIP (Narrow 0.300)

(LTC DWG # 05-08-1510)

0.045 – 0.065

(1.143 – 1.651)

0.130 ± 0.005

(3.302 ± 0.127)

876

0.400*
(10.160)

MAX

5

0.065

(1.651)

0.009 – 0.015

(0.229 – 0.381)

+0.025

0.325
–0.015

+0.635

8.255

()

–0.381

*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)

TYP

0.005

(0.127)

MIN

0.100 ± 0.010

(2.540 ± 0.254)

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 represen­tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

0.125

(3.175)

MIN



0.018 ± 0.003

(0.457 ± 0.076)

0.015

(0.380)

MIN

0.255 ± 0.015*
(6.477 ± 0.381)





12

3

4

N8 0695

11

LT1635

TYPICAL APPLICATION

U

1A Shunt Battery Charger (I

1A
SOLAR
ARRAY

*DALE HLM-10

200mV

8

PACKAGE DESCRIPTION

+

LT1635

REF

–

= 230µA, V

DARK

1M

220Ω3

7

+

LT1635

7V

1

68k

2k

2

1M

OP AMP

–

4

FLOAT

6

= 14V)

100nF

TIP121

7.5Ω*
10W

U

Dimensions in inches (millimeters) unless otherwise noted.

S8 Package

8-Lead Plastic Small Outline (Narrow 0.150)

(LTC DWG # 05-08-1610)

2A

12V
5A
GELCEL

1635 TA09

0.189 – 0.197*
(4.801 – 5.004)

0.010 – 0.020

(0.254 – 0.508)

0.008 – 0.010

(0.203 – 0.254)

*

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



× 45°

0.016 – 0.050

0.406 – 1.270

0.053 – 0.069

(1.346 – 1.752)

0°– 8° TYP

(0.355 – 0.483)

0.014 – 0.019

0.004 – 0.010

(0.101 – 0.254)

0.050

(1.270)

BSC

0.228 – 0.244

(5.791 – 6.197)

7

8

1

2

5

6

0.150 – 0.157**
(3.810 – 3.988)

SO8 0695

3

4

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12

Linear Technolog y Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417 ● [phone]
FAX: [phone]

●

TELEX: 499-3977 ● www.linear-tech.com

1635f LT/TP 0997 4K • PRINTED IN USA

 LINEAR TECHNOLOGY CORPORATION 1997