Linear Technology LTC1695 Datasheet

FEATURES

■

Complete SMBus/I2CTM Brushless DC Fan Speed
Control System in a 5-Pin SOT-23 package

■

0.75Ω PMOS Linear Regulator with 180mA
Output Current Rating

■

0V to 4.922V Output Voltage Range Controlled by a
6-Bit DAC

■

Simple 2-Wire SMBus/I2C Interface

■

250ms Internal Timer Ensures Fan Start-Up

■

Current Limit and Thermal Shutdown

■

Fault Status Indication via SMBus Host Readback

U

APPLICATIO S

■

Notebook Computers

■

Spot Cooling

■

Portable Instruments

■

Battery-Powered Systems

■

DC Motor Control

■

White LED Power Supplies

■

Programmable Low Dropout Regulator

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

2

C is a trademark of Philips Electronics N.V.

I

LTC1695

SMBus/I2C Fan Speed

Controller in SOT-23

U

DESCRIPTIO

The LTC®1695 fan speed controller provides all the func­tions necessary for a power management microprocessor
to regulate the speed of a 5V brushless DC fan via a 2-wire
SMBus/I2C interface. Fan speed is controlled according to
the system’s required temperature profile and permits
lower fan power consumption, longer battery run time and
lower acoustical generated noise versus systems that
only provide simple on-off control for the fan.

The LTC1695 incorporates a 180mA low dropout linear
regulator, a 2-wire SMBus/I2C interface and a 6-bit DAC.
Fan speed is controlled by varying the fan’s terminal
voltage through the output voltage of the LTC1695’s linear
regulator. The LTC1695’s output voltage is programmed
by sending a 6-bit digital code to the LTC1695 DAC via the
SMBus. To eliminate fan start-up problems at lower fan
voltages, users can enable the LTC1695’s boost start
feature that provides the DAC’s full-scale output voltage
for 250ms before decreasing to the programmed output
voltage.

The LTC1695 includes output current limiting and thermal
shutdown as well as status monitors that can be read back
by the microprocessor during fault conditions. The
LTC1695 is available in a 5-lead SOT-23 package.

TYPICAL APPLICATION

5V

15

V

V

CC

+

10µF

2

3

SYSTEM

CONTROLLER

LTC1695

GND

SCL

OUT

SDA

U

4

4.7µF

Fan Voltage and Current vs DAC Code

120

VCC = 5V

= 25°C

T

A

100

80

+

5V DC FAN
SUNON
KDE0502PFB2-8

0.6W, 1.7 CFM
(25 • 25 • 10)mm

1695 • TA01

60

3

40

LOAD CURRENT (mA)

20

0

0

10 20

I

LOAD

40 60 70

30 50

DAC CODE

V

OUT

6

5

OUTPUT VOLTAGE (V)

4

3

2

1

0

1695 • TA02

1

LTC1695

WW

W

ABSOLUTE AXI U RATI GS

U

UUW

PACKAGE/ORDER I FOR ATIO

(Note 1)

Terminal Voltages

Supply Voltage (VCC) ............................................. 7V

All Other Inputs ........................ –0.3V to (V

+ 0.3V)

CC

Operating Temperature Range ..................... 0°C to 70°C

GND 2

SCL 3

Junction Temperature........................................... 125°C

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

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

Consult factory for Industrial and Military grade parts.

ELECTRICAL CHARACTERISTICS

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

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

CC

I

CC

DAC

V

LSB

V

OS

DNL Differential Nonlinearity I
INL Integral Nonlinearity I
V

FS

V

ZS

R

ON(P)

Timer and Thermal Shutdown

V

UVLO

T

BST_ST

T

THERMAL

I

FAULT

SMBus SCL, SDA Inputs

V

IH

V

IL

I

IN

C

IN

t

ON

t

OFF

V

OL

Supply Voltage Range 4.5 5 5.5 V
Supply Current, Operating V

Supply Current, Shutdown DAC Code = 0

DAC Resolution Guaranteed Monotonic ● 6 Bits
1LSB Resolution I
Offset Error I

V

, DAC Full Scale I

OUT

V

, DAC Zero Scale R

OUT

P-Channel On Resistance I

Undervoltage Lockout Voltage Rising V
Boost Start Timer I
Thermal Shutdown Temperature (Note 3) 155 °C
Output Current Limit Threshold V

Input High Threshold ● 2.1 V
Input Low Threshold ● 0.8 V
Input Current SCL, SDA = 0V or 5V ● ±0.1 ±5 µA
Input Capacitance (Note 3) 3 pF
Switch On Time from V

Stop Condition (f
Switch Off Time from V

Stop Condition (f
SDA Output Low Voltage I

= 100kHz) I

SMBus

= 100kHz) I

SMBus

The ● denotes the specifications which apply over the full operating

= 5V unless otherwise stated.

CC

= Full Scale, I

OUT

= 1mA ● 73 78 83 mV

LOAD

= 1mA ● ±1 LSB

LOAD

= 1mA (Note 2) ● ±0.75 LSB

LOAD

= 1mA (Note 2) ● ±0.75 LSB

LOAD

= 20mA ● 4.5 4.93 V

LOAD

= 150mA ● 4.5 4.9 V

I

LOAD

= 1kΩ ● 085 mV

LOAD

= 150mA 0.75 Ω

LOAD

CC

= 10mA, C

LOAD

= 0V, DAC Code = 63 ● 180 390 850 mA

OUT

from Zero Scale to Full Scale, ● 50 500 µs

OUT

= 1mA, C

LOAD

from Full Scale to Zero Scale, ● 150 500 µs

OUT

= 150mA, C

LOAD

= 3mA ● 150 400 mV

PULLUP

LOAD

= 4.7µF ● 75 250 1000 ms

LOAD

= 4.7µF

LOAD

LOAD

TOP VIEW

V

1

CC

S5 PACKAGE

5-LEAD PLASTIC SOT-23

T

= 125°C, θJA = 256°C/W

JMAX

SEE THE APPLICATIONS

INFORMATION SECTION.

= 150mA ● 150.7 155 mA

= 4.7µF

5 V

OUT

4 SDA

● 80 200 µA

● 2.3 2.9 3.5 V

ORDER PART

NUMBER

LTC1695CS5

S5 PART MARKING

LTIY

2

LTC1695

TEMPERATURE (°C)

–50

SUPPLY CURRENT (µA)

250

200

150

100

50

0

0

50

75

1695 • G03

–25

25

100

125

CODE 0

CODE 63

VCC = 5V

ELECTRICAL CHARACTERISTICS

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

The ● denotes the specifications which apply over the full operating

= 5V unless otherwise stated.

CC

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
SMBus TIMING (Note 4)

f

SMB

t

BUF

t

HD(STA)

t

SU(STA)

t

SU(STO)

t

HD(DAT)

t

SU(DAT)

t

LOW

t

HIGH

t

f

t

r

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

Note 2: INL, DNL specs are specified under a 1mA I
linear regulator from operating in dropout at higher DAC codes. DNL is

SMBus Operating Frequency ● 10 100 kHz
Bus Free Time Between Stop and Start ● 4.7 µs
Hold Time After (Repeated) Start Condition ● 4.0 µs
Repeated Start Condition Setup Time ● 4.7 µs
Stop Condition Setup Time ● 4.0 µs
Data Hold Time ● 300 ns
Data Setup Time ● 250 ns
Clock Low Period ● 4.7 µs
Clock High Period ● 4.0 50 µs
Clock/Data Fall Time ● 300 ns
Clock/Data Rise Time ● 1000 ns

Note 3: This typical specification is based on lab measurements and is not
production tested.

condition to keep the

LOAD

Note 4: Guaranteed by design and not tested. Please refer to the Timing

Diagram section for additional information.
measured from code 0 to code 63, taking into account the untrimmed offset
at code 0. Please refer to the Definitions section for more details.

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Output Voltage vs
DAC Code

6

VCC = 5V

= 25°C

T

A

5

= 1mA

I

LOAD

4

3

2

OUTPUT VOLTAGE (V)

1

0

0

20 30 40

10

DAC CODE

50 60 63

1695 • G01

No Load Supply Current vs Supply
Voltage

250

TA = 25°C

200

150

100

SUPPLY CURRENT (µA)

50

0

4.0

4.5

5.0

SUPPLY VOLTAGE (V)

CODE 63

5.5

CODE 0

6.0

1695 • G02

No Load Supply Current vs
Temperature

3

LTC1695

TEMPERATURE (°C)

–50

OUTPUT VOLTAGE (V)

4.95

4.93

4.91

4.89

4.87

4.85
0

50

75

1695 • G09

–25

25

100

125

VCC = 5V
CODE 63

I

LOAD

= 1mA

I

LOAD

= 150mA

CODE

0

INL (LSB)

0.25

0.15

0.05

–0.05

–0.15

–0.25

10

20 30 40

1695 • G12

50 60 63

VCC = 5V
I

LOAD

= 1mA

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Ground Current (Dropout Mode) vs
Supply Voltage

900

TA =25°C
I

= 180mA

LOAD

800

700

600

GROUND CURRENT (µA)

500

400

4.0

4.5
SUPPLY VOLTAGE (V)

CODE 63

5.0

Output Voltage (Full Scale) vs
Load Current

4.930

4.920

4.910

4.900

4.890

OUTPUT VOLTAGE (V)

4.880

4.870

5.5

VCC = 5V

= 25°C

T

A

CODE 63

1695 • G04

6.0

Ground Current (Dropout Mode)
vs Temperature

900

VCC = 5V

= 180mA

I

LOAD

850

800

750

700

GROUND CURRENT (µA)

650

600

–50

–25 0

TEMPERATURE (°C)

CODE 63

50 100 125

25 75

Output Voltage (Midscale) vs Load
Current

2.505

2.500

2.495

2.490

OUTPUT VOLTAGE (V)

2.485

CODE 32

1695 • G05

VCC = 5V

= 25°C

T

A

Dropout Voltage vs
Load Current

175

VCC = 5V

150

125

100

75

50

DROPOUT VOLTAGE (mV)

25

0

0

TA = 25°C

40 8060 100 120 140 180160

20

LOAD CURRENT (mA)

TA = 85°C

TA = –40°C

Output Voltage (Full Scale) vs
Temperature

1695 • G06

4.860

2.510

2.505

2.500

2.495

2.490

OUTPUT VOLTAGE (V)

2.485

2.480

4

0

40 60 80 120100 140 180160

20

LOAD CURRENT (mA)

1695 • G07

2.480
0

20 60

40

80

LOAD CURRENT (mA)

100

120

180160140

1695 • G08

Output Voltage (Midscale) vs
Temperature Integral Nonlinearity (INL)

VCC = 5V
CODE 32

I

= 1mA

LOAD

I

= 150mA

LOAD

–50

–25 0

TEMPERATURE (°C)

50 100 125

25 75

1695 • G10

Differential Nonlinearity (DNL)

0.25
VCC = 5V

= 1mA

I

LOAD

0.15

0.05

DNL (LSB)

–0.05

–0.15

–0.25

0

20 30 40

10

CODE

50 60 63

1695 • G11

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Boost Start Timer vs Supply

POR and UVLO vs Temperature

3.00

POR (RISING VCC)

2.90

Voltage Boost Start Timer vs Temperature

350

TA = 25°C

= 10mA

I

LOAD

300

600

500

400

LTC1695

VCC = 5V

= 10mA

I

LOAD

2.80

SUPPLY VOLTAGE (V)

2.70

2.60
–50

UVLO (FALLING VCC)

–25 0 25 50

TEMPERATURE (°C)

Current Limit Threshold vs
Supply Voltage

425

TA = 25°C

400

375

350

CURRENT LIMIT (mA)

325

300

4.5

4.75
SUPPLY VOLTAGE (V)

5.0

5.25

10075 125

1695 • G13

5.5

1695 • G16

250

200

BOOST START TIMER (ms)

150

4.0

4.5
SUPPLY VOLTAGE (V)

Current Limit Threshold
vs Temperature

600

VCC = 5V

500

400

300

200

CURRENT LIMIT (mA)

100

0

–40

02040

–20

TEMPERATURE (°C)

5.0

5.5

1695 • G14

60 80 90

1695 • G17

300

200

BOOST START TIMER (ms)

100

6.0

120

100

80

60

40

20

JUNCTION TEMPERATURE INCREASE (°C)

0

0

0255075

–25

TEMPERATURE (°C)

Junction Temperature Increase
vs Load Current

VCC = 5V, TA = 25°C,
SOT-23 THERMAL RESISTANCE
= 150°C/W (PCB SOLDERED)
SEE APPLICATIONS
INFORMATION.

CODE 16 (1.25V)

CODE 32 (2.5V)

CODE 48 (3.75V)

CODE 63 (4.922V)

40 60 80 180

0 20 100 140 160

LOAD CURRENT (mA)

120

100

1695 • G15

1695 • G18

V

(AC)

OUT

20mV/DIV

I

LOAD

50mA/DIV

Load Transient Response
Code 32, 5mA to 55mA

V

= 5V

CC

= 4.7µF TANTALUM

C

OUT

100µs/DIV

1695 • G19

V

(AC)

OUT

10mV/DIV

I

LOAD

50mA/DIV

Load Transient Response
Code 32, 50mA to 100mA

V

= 5V

CC

C

= 4.7µF TANTALUM

OUT

100µs/DIV

1695 • G20

5

LTC1695

1695 • G23

V

OUT

2V/DIV

100ms/DIV

V

CC

= 5V

C

IN

= 10µF

C

OUT

= 4.7µF

I

LOAD

= 1mA

UW

TYPICAL PERFOR A CE CHARACTERISTICS

V

(AC)

OUT

20mV/DIV

I

LOAD

50mA/DIV

Load Transient Response
Dropout (Code 63), 5mA to 55mA

V

= 5V

CC

= 4.7µF TANTALUM

C

OUT

100µs/DIV

1695 • G21

V
20mV/DIV

50mA/DIV

Load Transient Response
Dropout (Code 63), 50mA to 100mA

(AC)

OUT

I

LOAD

V

= 5V

CC

= 4.7µF TANTALUM

C

OUT

UUU

PIN FUNCTIONS

VCC (Pin 1): Power Supply Input. VCC supplies current to
the internal control circuitry, serves as the reference for
the 6-bit DAC and acts as the power path for the P-channel
low dropout linear regulator. Bypass V
with a low ESR capacitor ≥10µF.

GND (Pin 2): Ground. Tie GND to the ground plane.
SCL (Pin 3): SMBus Clock Input. Data is shifted into SDA

on the rising edge of the SCL clock signal during data
transfer.

directly to ground

CC

Boost Start Timer

100µs/DIV

1695 • G22

SDA (Pin 4): SMBus Bidirectional Data Input/Digital Out­put. SDA is an open drain output and requires a pull-up
resistor or current source to VCC. Data is shifted into SDA
and acknowledged by SDA.

V

(Pin 5): Linear Regulator Output. Connect directly to

OUT

the fan’s +VE terminal. V

is set to VZS (code 0) on

OUT

power-up. For good transient response and stability, use
a general purpose, low cost, medium ESR (0.1Ω to 1Ω)
tantalum or electrolytic capacitor. LTC recommends a
surface mount tantalum capacitor of ≥4.7µF.

6