LTC1695
SMBus/I
2
C Fan Speed
Controller in SOT-23
FEATURES
s
s
DESCRIPTIO
s
s
s
s
s
Complete SMBus/I
2
C
TM
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/I
2
C Interface
250ms Internal Timer Ensures Fan Start-Up
Current Limit and Thermal Shutdown
Fault Status Indication via SMBus Host Readback
The LTC
®
1695 fan speed controller provides all the func-
tions necessary for a power management microprocessor
to regulate the speed of a 5V brushless DC fan via a 2-wire
SMBus/I
2
C 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/I
2
C 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.
APPLICATIO S
s
s
s
s
s
s
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.
I
2
C is a trademark of Philips Electronics N.V.
TYPICAL APPLICATION
5V
1
V
CC
V
OUT
5
LOAD CURRENT (mA)
Fan Voltage and Current vs DAC Code
120
100
80
I
LOAD
60
40
20
1695 • TA01
V
CC
= 5V
T
A
= 25°C
+
10µF
2
LTC1695
GND
4
4.7µF
+
5V DC FAN
SUNON
KDE0502PFB2-8
0.6W, 1.7 CFM
(25 • 25 • 10)mm
3
3
SYSTEM
CONTROLLER
SCL
SDA
0
0
10
U
6
5
OUTPUT VOLTAGE (V)
U
U
4
V
OUT
3
2
1
0
70
20
40
30
DAC CODE
50
60
1695 • TA02
1
LTC1695
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
CC
1
GND 2
SCL 3
4 SDA
5 V
OUT
Terminal Voltages
Supply Voltage (V
CC
) ............................................. 7V
All Other Inputs ........................ –0.3V to (V
CC
+ 0.3V)
Operating Temperature Range ..................... 0°C to 70°C
Junction Temperature ........................................... 125°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC1695CS5
S5 PART MARKING
LTIY
S5 PACKAGE
5-LEAD PLASTIC SOT-23
T
JMAX
= 125°C,
θ
JA
= 256°C/W
SEE THE APPLICATIONS
INFORMATION SECTION.
Consult factory for Industrial and Military grade parts.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V unless otherwise stated.
SYMBOL
V
CC
I
CC
DAC
DAC Resolution
V
LSB
V
OS
DNL
INL
V
FS
V
ZS
R
ON(P)
V
UVLO
T
BST_ST
T
THERMAL
I
FAULT
V
IH
V
IL
I
IN
C
IN
t
ON
t
OFF
V
OL
1LSB Resolution
Offset Error
Differential Nonlinearity
Integral Nonlinearity
V
OUT
, DAC Full Scale
V
OUT
, DAC Zero Scale
P-Channel On Resistance
Undervoltage Lockout Voltage
Boost Start Timer
Thermal Shutdown Temperature
Output Current Limit Threshold
Input High Threshold
Input Low Threshold
Input Current
Input Capacitance
Switch On Time from
Stop Condition (f
SMBus
= 100kHz)
Switch Off Time from
Stop Condition (f
SMBus
= 100kHz)
SDA Output Low Voltage
SCL, SDA = 0V or 5V
(Note 3)
V
OUT
from Zero Scale to Full Scale,
I
LOAD
= 1mA, C
LOAD
= 4.7µF
V
OUT
from Full Scale to Zero Scale,
I
LOAD
= 150mA, C
LOAD
= 4.7µF
I
PULLUP
= 3mA
q
q
q
ELECTRICAL CHARACTERISTICS
PARAMETER
Supply Voltage Range
Supply Current, Operating
Supply Current, Shutdown
CONDITIONS
V
OUT
= Full Scale, I
LOAD
= 150mA
DAC Code = 0
Guaranteed Monotonic
I
LOAD
= 1mA
I
LOAD
= 1mA
I
LOAD
= 1mA (Note 2)
I
LOAD
= 1mA (Note 2)
I
LOAD
= 20mA
I
LOAD
= 150mA
R
LOAD
= 1kΩ
I
LOAD
= 150mA
Rising V
CC
I
LOAD
= 10mA, C
LOAD
= 4.7µF
(Note 3)
V
OUT
= 0V, DAC Code = 63
q
q
q
q
q
MIN
4.5
TYP
5
150.7
80
6
MAX
5.5
155
200
UNITS
V
mA
µA
Bits
q
q
q
q
q
q
q
q
73
78
83
±1
±0.75
±0.75
4.5
4.5
4.93
4.9
0
0.75
85
Timer and Thermal Shutdown
2.3
75
180
2.1
0.8
±0.1
3
50
150
150
500
500
400
±5
2.9
250
155
390
850
3.5
1000
V
ms
°C
mA
V
V
µA
pF
µs
µs
mV
SMBus SCL, SDA Inputs
q
q
q
2
U
mV
LSB
LSB
LSB
V
V
mV
Ω
W
U
U
W W
W
LTC1695
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V unless otherwise stated.
SYMBOL
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
PARAMETER
SMBus Operating Frequency
Bus Free Time Between Stop and Start
Hold Time After (Repeated) Start Condition
Repeated Start Condition Setup Time
Stop Condition Setup Time
Data Hold Time
Data Setup Time
Clock Low Period
Clock High Period
Clock/Data Fall Time
Clock/Data Rise Time
CONDITIONS
q
q
q
q
q
q
q
q
q
q
q
ELECTRICAL CHARACTERISTICS
SMBus TIMING (Note 4)
MIN
10
4.7
4.0
4.7
4.0
300
250
4.7
4.0
TYP
MAX
100
UNITS
kHz
µs
µs
µs
µs
ns
ns
µs
50
300
1000
µs
ns
ns
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
LOAD
condition to keep the
linear regulator from operating in dropout at higher DAC codes. DNL is
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.
Note 3:
This typical specification is based on lab measurements and is not
production tested.
Note 4:
Guaranteed by design and not tested. Please refer to the Timing
Diagram section for additional information.
TYPICAL PERFOR A CE CHARACTERISTICS
Output Voltage vs
DAC Code
6
5
OUTPUT VOLTAGE (V)
250
V
CC
= 5V
T
A
= 25°C
I
LOAD
= 1mA
SUPPLY CURRENT (µA)
4
3
2
1
0
SUPPLY CURRENT (µA)
0
10
20
30
40
DAC CODE
U W
50
1695 • G01
No Load Supply Current vs Supply
Voltage
250
No Load Supply Current vs
Temperature
V
CC
= 5V
T
A
= 25°C
CODE 63
200
200
CODE 63
150
150
100
CODE 0
100
CODE 0
50
50
60 63
0
4.0
5.0
4.5
5.5
SUPPLY VOLTAGE (V)
6.0
1695 • G02
0
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
1695
•
G03
3
LTC1695
TYPICAL PERFOR A CE CHARACTERISTICS
Ground Current (Dropout Mode) vs
Supply Voltage
900
T
A
=25°C
I
LOAD
= 180mA
CODE 63
700
GROUND CURRENT (µA)
DROPOUT VOLTAGE (mV)
GROUND CURRENT (µA)
800
600
500
400
4.0
5.0
4.5
5.5
SUPPLY VOLTAGE (V)
Output Voltage (Full Scale) vs
Load Current
4.930
4.920
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
4.910
CODE 63
4.900
4.890
4.880
4.870
4.860
OUTPUT VOLTAGE (V)
0
20
40
60 80 100 120 140 160 180
LOAD CURRENT (mA)
1695 • G07
Output Voltage (Midscale) vs
Temperature
2.510
2.505
OUTPUT VOLTAGE (V)
V
CC
= 5V
CODE 32
I
LOAD
= 1mA
2.500
2.495
2.490
DNL (LSB)
INL (LSB)
I
LOAD
= 150mA
2.485
2.480
–50 –25
50
25
75
0
TEMPERATURE (°C)
4
U W
1695 • G04
Ground Current (Dropout Mode)
vs Temperature
900
850
800
CODE 63
750
700
650
600
–50 –25
V
CC
= 5V
I
LOAD
= 180mA
175
150
Dropout Voltage vs
Load Current
V
CC
= 5V
T
A
= 85°C
125
100
T
A
= 25°C
75
50
25
0
T
A
= – 40°C
6.0
50
25
75
0
TEMPERATURE (°C)
100
125
0
20
40
60 80 100 120 140 160 180
LOAD CURRENT (mA)
1695 • G06
1695 • G05
Output Voltage (Midscale) vs Load
Current
2.505
4.95
Output Voltage (Full Scale) vs
Temperature
V
CC
= 5V
CODE 63
4.93
I
LOAD
= 1mA
V
CC
= 5V
T
A
= 25°C
V
CC
= 5V
T
A
= 25°C
2.500
2.495
CODE 32
2.490
4.91
I
LOAD
= 150mA
4.89
2.485
4.87
2.480
0
20
40
60 80 100 120 140 160 180
LOAD CURRENT (mA)
1695 • G08
4.85
–50
–25
50
0
75
25
TEMPERATURE (°C)
100
125
1695 • G09
Differential Nonlinearity (DNL)
0.25
V
CC
= 5V
I
LOAD
= 1mA
0.25
Integral Nonlinearity
(INL)
V
CC
= 5V
I
LOAD
= 1mA
0.15
0.15
0.05
0.05
–0.05
–0.05
–0.15
–0.15
100
125
–0.25
0
10
20
30
40
CODE
50
60 63
1695 • G11
–0.25
0
10
20
30
40
CODE
50
60 63
1695 • G12
1695 • G10
LTC1695
TYPICAL PERFOR A CE CHARACTERISTICS
POR and UVLO vs Temperature
3.00
350
T
A
= 25°C
I
LOAD
= 10mA
BOOST START TIMER (ms)
SUPPLY VOLTAGE (V)
2.90
300
BOOST START TIMER (ms)
POR (RISING V
CC
)
2.80
UVLO (FALLING V
CC
)
2.70
2.60
–50
–25
0
25
50
75
TEMPERATURE (°C)
Current Limit Threshold vs
Supply Voltage
425
T
A
= 25°C
400
CURRENT LIMIT (mA)
CURRENT LIMIT (mA)
JUNCTION TEMPERATURE INCREASE (°C)
375
350
325
300
4.5
5.0
4.75
5.25
SUPPLY VOLTAGE (V)
Load Transient Response
Code 32, 5mA to 55mA
V
OUT
(AC)
20mV/DIV
I
LOAD
50mA/DIV
100µs/DIV
V
CC
= 5V
C
OUT
= 4.7µF TANTALUM
U W
100
1695 • G13
1695 • G16
Boost Start Timer vs Supply
Voltage
600
500
400
300
200
100
150
4.0
Boost Start Timer vs Temperature
V
CC
= 5V
I
LOAD
= 10mA
250
200
125
5.0
5.5
4.5
SUPPLY VOLTAGE (V)
6.0
1695 • G14
0
–25
0
25
50
TEMPERATURE (°C)
75
100
1695 • G15
Current Limit Threshold
vs Temperature
600
V
CC
= 5V
500
400
300
200
100
0
–40
120
100
80
60
40
20
0
Junction Temperature Increase
vs Load Current
V
CC
= 5V, T
A
= 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)
0
20
40
60 80 100 120 140 160 180
LOAD CURRENT (mA)
1695 • G18
5.5
–20
0
20
40
TEMPERATURE (°C)
60
80 90
1695 • G17
Load Transient Response
Code 32, 50mA to 100mA
V
OUT
(AC)
10mV/DIV
I
LOAD
50mA/DIV
100µs/DIV
V
CC
= 5V
C
OUT
= 4.7µF TANTALUM
1695 • G19
1695 • G20
5
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