LTC6907
Micropower, 40kHz to 4MHz
Resistor Set Oscillator
in SOT-23
FEATURES
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■
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■
DESCRIPTIO
Supply Current: 36µA at 400kHz
1% Frequency Accuracy (from 0°C to 70°C)
Frequency Range: 40kHz to 4MHz
One Resistor Sets the Oscillator Frequency
–40°C to 125°C Operating Temperature Range
Start-Up Time Under 200µs at 4MHz
First Cycle After Power-Up is Accurate
150Ω CMOS Output Driver
Low Profile (1mm) SOT-23 (ThinSOT
TM
) Package
The LTC
®
6907 is a precision programmable oscillator that
is versatile, compact and easy to use. Micropower opera-
tion benefits portable and battery-powered equipment. At
400kHz, the LTC6907 consumes 36µA on a 3V supply.
A single resistor programs the oscillator frequency over a
10:1 range with better than 0.65% initial accuracy. The
output frequency can be divided by 1, 3 or 10 to span a
100:1 total frequency range, 40kHz to 4MHz.
The LTC6907 is easily programmed according to this
simple formula:
i
⎧
10, DIV Pi n
=
V
+
4MHz
⎛
50k
⎞
⎪
, N
=
⎨
3, DIV Pin
=
Open
=
•
⎜
N
⎠
⎝
R
SET
⎟
⎪
1, DIV Pin
=
GND
⎩
APPLICATIO S
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Low Cost Precision Programmable Oscillator
Rugged, Compact Micropower Replacement for
Crystal and Ceramic Oscillators
High Shock and Vibration Environments
Portable and Battery-Powered Equipment
PDAs and Cellular Phones
ƒ
OUT
The LTC6907 is available in the 6-lead SOT-23 (ThinSOT)
package.
Contact LTC Marketing for a version of the part with a
shutdown feature or lower frequency operation.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
Micropower Clock Generator
LTC6907
3V TO 3.6V
0.1µF
÷10
÷3
÷1
V
+
GND
DIV
OUT
40kHz TO 4MHz
Typical Supply Current vs Frequency
1000
C
LOAD
= 5pF
T = 25°C
:
3.3V, –1
:
3.3V, –3
:
3.3V, –10
100
SET
R
SET
50k TO 500k
6907 TA01
SUPPLY CURRENT (µA)
GRD
10
10
100
1000
OUTPUT FREQUENCY (kHz)
U
10000
6907 TA02
U
U
6907fa
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LTC6907
ABSOLUTE
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
OUT 1
GND 2
DIV 3
6 V
+
5 GRD
4 SET
(Note 1)
V
+
................................................................– 0.3V to 6V
DIV to GND .................................... – 0.3V to (V
+
+ 0.3V)
SET to GND ................................... – 0.3V to (V
+
+ 0.3V)
GRD to GND .................................. – 0.3V to (V
+
+ 0.3V)
ORDER PART NUMBER
LTC6907CS6
LTC6907IS6
LTC6907HS6
S6 PART MARKING*
LTBTX
Operating Temperature Range (Note 7)
LTC6907C .......................................... – 40°C to 85°C
LTC6907I ............................................ – 40°C to 85°C
LTC6907H ........................................ – 40°C to 125°C
Specified Temperature Range (Note 7)
LTC6907C ............................................... 0°C to 70°C
LTC6907I ............................................ – 40°C to 85°C
LTC6907H ........................................ – 40°C to 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 150°C,
θ
JA
= 200°C/W
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
*The temperature grade is indicated by a label on the shipping container.
ELECTRICAL CHARACTERISTICS
SYMBOL
∆f
PARAMETER
Frequency Accuracy (Notes 2, 3)
The
●
denotes the specifications which apply over the full specified
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 3V to 3.6V, C
L
= 5pF, Pin 3 = V
+
unless otherwise noted.
All voltages are with respect to GND.
CONDITIONS
V
+
= 3V to 3.6V 400kHz
≤
f
≤
4MHz
400kHz
≤
f
≤
4MHz, LTC6907C
400kHz
≤
f
≤
4MHz, LTC6907I, H
R
SET
= 158k
V
+
= 3V to 3.6V, 50k
≤
R
SET
≤
500k
Pin 3 = V
+
, 50k
≤
R
SET
≤
500k
Pin 3 = Open, 50k
≤
R
SET
≤
500k
Pin 3 = 0V, 50k
≤
R
SET
≤
500k
Pin 3 = V
+
Stability Over 1 Year
Stability Over 10 Years
●
●
●
●
●
●
MIN
TYP
±0.25
MAX
±0.65
±1
±1.3
500
UNITS
%
%
%
kΩ
%/°C
%/V
%
%
%
ppm/√kHr
ppm
ppm
R
SET
∆f/∆T
∆f/∆V
Frequency-Setting Resistor Range
Frequency Drift Over Temp (Note 3)
Frequency Drift Over Supply (Note 3)
Timing Jitter (Peak-to-Peak) (Note 4)
50
±0.005
0.06
0.12
0.28
0.60
300
888
2809
43
3
40
36
305
275
3.1
2.6
50
S
f
Long-Term Stability of Output Frequency
(Note 9)
Duty Cycle
Operating Supply Range (Note 8)
Power Supply Current
DC
V
+
I
S
57
3.6
55
48
406
366
R
SET
= 500k, Pin 3 = 0V, R
L
= 10M
(DIV = 1, f
OUT
= 400kHz)
R
SET
= 50k, Pin 3 = 0V, R
L
= 10M
(DIV = 1, f
OUT
= 4MHz)
V
+
= 3.6V
V
+
= 3V
V
+
= 3.6V
V
+
= 3V
V
+
= 3.6V
V
+
= 3V
V
+
= 3.6V
V
+
= 3V
●
●
●
●
●
●
●
●
●
●
V
IH
V
IL
I
DIV
High Level DIV Input Voltage
Low Level DIV Input Voltage
DIV Input Current (Note 5)
Pin 3 = V
+
Pin 3 = 0V
0.5
0.2
–2
1
–1
2
V
+
= 3.6V
2
U
%
V
µA
µA
µA
µA
V
V
V
V
µA
µA
6907fa
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U
U
W W
W
LTC6907
ELECTRICAL CHARACTERISTICS
SYMBOL
V
OH
PARAMETER
High Level Output Voltage (Note 5)
The
●
denotes the specifications which apply over the full specified
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 3V to 3.6V, C
L
= 5pF, Pin 3 = V
+
unless otherwise noted.
All voltages are with respect to GND.
CONDITIONS
V
+
= 3.6V
V
+
= 3V
V
OL
Low Level Output Voltage (Note 5)
V
+
= 3.6V
V
+
= 3V
t
r
t
f
VGS
OUT Rise Time (Note 6)
OUT Fall Time (Note 6)
GRD Pin Voltage Relative to SET Pin
Voltage
V
+
= 3.6V
V
+
= 3V
V
+
= 3.6V
V
+
= 3V
–10µA
≤
I
GRD
≤
0.3µA
●
MIN
I
OH
= – 100µA
I
OH
= – 1mA
I
OH
= – 100µA
I
OH
= – 1mA
I
OL
= 100µA
I
OL
= 1mA
I
OL
= 100µA
I
OL
= 1mA
●
●
●
●
●
●
●
●
TYP
3.57
3.45
2.97
2.80
0.08
0.25
0.07
0.25
10
25
10
25
MAX
UNITS
V
V
V
V
3.40
3.10
2.8
2.5
0.2
0.8
0.2
0.8
V
V
V
V
ns
ns
ns
ns
–10
10
mV
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
Some frequencies may be generated using two different values of
R
SET
. For these frequencies, the error is specified assuming that the larger
value of R
SET
is used.
Note 3:
Frequency accuracy is defined as the deviation from the f
OUT
equation.
Note 4:
Jitter is the ratio of the peak-to-peak deviation of the period to the
mean of the period. This specification is based on characterization and is
not 100% tested.
Note 5:
Current into a pin is given as a positive value. Current out of a pin
is given as a negative value.
Note 6:
Output rise and fall times are measured between the 10% and
90% power supply levels.
Note 7:
The LTC6907C is guaranteed to meet specified performance from
0°C to 70°C. The LTC6907C is designed, characterized and expected to
meet specified performance from –40°C to 85°C but is not tested or QA
sampled at these temperatures. The LTC6907I is guaranteed to meet
specified performance from –40°C to 85°C.
Note 8:
Consult the Applications Information section for operation with
supplies higher than 3.6V.
Note 9:
Long term drift on silicon oscillators is primarily due to the
movement of ions and impurities within the silicon and is tested at 30°C
under otherwise nominal operating conditions. Long term drift is specified
as ppm/√kHr due to the typically non-linear nature of the drift. To calculate
drift for a set time period, translate that time into thousands of hours, take
the square root and multiply by the typical drift number. For instance, a
year is 8.77kHr and would yield a drift of 888ppm at 300ppm/√kHr. Ten
years is 87.7kHr and would yield a drift of 2,809 ppm at 300 ppm/√kHr.
Drift without power applied to the device may be approximated as 1/10
th
of
the drift with power, or 30ppm/√kHr for a 300ppm/√kHr device.
6907fa
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LTC6907
TYPICAL PERFOR A CE CHARACTERISTICS
Typical Frequency Error
vs Power Supply Voltage
0.060%
0.040%
T = 25°C
C
LOAD
= 5pF
1.0%
0.020%
0.000%
–0.020%
0.4%
0.2%
R
SET
= 50k
FREQUENCY ERRROR (%)
FREQUENCY ERROR (%)
FREQUENCY ERROR (%)
–0.040%
–0.060%
3
3.1
3.2
3.3
3.4
SUPPLY VOLTAGE (V)
Typical Supply Current
vs Frequency
1000
C
LOAD
= 5pF
T = 25°C
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
:
3.3V, –3
:
3.3V, –10
100
R
SET
VOLTAGE (V)
:
3.3V, –1
10
10
100
1000
OUTPUT FREQUENCY (kHz)
Output Waveform, 400kHz
V
+
= 3.3V
0.5V/DIV
0.5V/DIV
4
U W
3.5
Typical Frequency Error
vs Temperature
V
+
V+ = 3V
0.8% C
LOAD
= 5pF
0.6%
Typical Frequency Error vs R
SET
0.150%
0.100%
T = 25°C
V
+
= 3V
C
LOAD
= 5pF
0.050%
0.000%
–0.050%
–0.100%
–0.150%
0%
–0.2%
–0.4%
–0.6%
R
SET
= 500k
R
SET
= 50k
R
SET
= 500k
–0.8%
–1.0%
–45
–25
–5
15
35 55
75 95 115
135
TEMPERATURE (°C)
6907 G02
3.6
6907 G01
0
100
500
200
300
400
SET RESISTOR (k OHMS)
600
6907 G03
Typical Supply Current
vs Load Capacitance
1000
900
800
700
600
500
400
300
200
100
0
10000
6907 G04
V
SET
vs Temperature
(V
SET
is the
Voltage Measured at the SET Pin)
0.8
T = 25°C
0.75
0.7
0.65
0.6
0.55
0.5
0.45
0.4
–45 –25 –5
V
+
= 3V
R
SET
= 50k, 3.0V
R
SET
= 50k, 3.6V
R
SET
= 500k, 3.0V
R
SET
= 500k, 3.6V
0
10
30
40
50
20
LOAD CAPACITANCE (pF)
60
6907 G05
15 35 55 75 95 115 135
TEMPERATURE (°C)
6907 G06
Output Waveform, 4MHz
V
+
= 3.3V
6907 G07
6907 G08
500ns/DIV
50ns/DIV
6907fa
LTC6907
PI FU CTIO S
OUT (Pin 1):
Oscillator Output. The OUT pin swings from
GND to V
+
with an output resistance of approximately
150Ω. For micropower operation, the load resistance
must be kept as high as possible and the load capacitance
as low as possible.
GND (Pin 2):
Ground.
DIV (Pin 3):
Divider Setting Input. This three-level input
selects one of three internal digital divider settings, deter-
mining the value of N in the frequency equation. Tie to GND
for
÷1,
leave floating for
÷3
and tie to V
+
for
÷10.
When left
floating, the LTC6907 pulls Pin 3 to mid-supply with a
2.5M resistor. When Pin 3 is floating, care should be taken
to reduce coupling from the OUT pin and its trace to Pin 3.
Coupling can be reduced by increasing the physical space
between traces or by shielding the DIV pin with grounded
metal.
SET (Pin 4):
Frequency Setting Resistor Input. Connect a
resistor, R
SET
, from this pin to GND to set the oscillator
frequency. For best performance use a precision metal or
thin-film resistor of 0.1% or better tolerance and 50ppm/°C
or better temperature coefficient. For lower accuracy
applications, an inexpensive 1% thick-film resistor may be
used. Limit the capacitance in parallel with R
SET
to less
than 10pF to reduce jitter and to ensure stability. The
voltage on the SET pin is approximately 650mV at 25°C
and decreases with temperature by about –2.3mV/°C.
GRD (Pin 5):
Guard Signal. This pin can be used to reduce
PC board leakage across the frequency setting resistor,
R
SET
. The GRD pin is held within a few millivolts of the SET
pin and shunts leakage current away from the SET pin. To
control leakage, connect a bare copper trace (a trace with
no solder mask) to GRD and loop it around the SET pin and
all PC board metal connected to SET. Careful attention to
board layout and assembly can prevent leakage currents.
The use of a guard ring provides additional shielding of
leakage currents from the SET pin and is optional. If
unused, the GRD pin should be left unconnected.
V
+
(Pin 6):
Voltage Supply (3V to 3.6V). A 0.1µF
decoupling capacitor should be placed as close as pos-
sible to this pin for best performance.
BLOCK DIAGRA
6
2
V
+
GND
V
SET
≅
V
GRD
≅
650mV
V
SET
R
SET
5
GRD
4
SET
I
SET
= I
FB
BUFFER
V
SET
+
–
W
U
U
U
FREQUENCY-TO-CURRENT
CONVERTERS
f
OSC
I
FB
I
FB
THREE-LEVEL
INPUT
DETECTOR
V
+
5M
DIV
5M
DIVIDER
SELECT
3
V
SET
OP AMP
VOLTAGE
CONTROLLED
OSCILLATOR
(MASTER OSCILLATOR)
f
OSC
= 4MHz •
50kΩ
R
SET
f
OSC
PROGRAMMABLE
DIVIDER (n)
(÷1,
÷3, ÷10)
150Ω DRIVER
OUT
1
6907 BD
6907fa
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