LTC6990
TimerBlox: Voltage
Controlled Silicon Oscillator
FEATURES
n
DESCRIPTION
The
LTC
®
6990
is a precision silicon oscillator with a pro-
grammable frequency range of 488Hz to 2MHz. It can be
used as a fixed-frequency or voltage-controlled oscillator
(VCO). The LTC6990 is part of the TimerBlox
®
family of
versatile silicon timing devices.
A single resistor, R
SET
, programs the LTC6990’s internal
master oscillator frequency. The output frequency is deter-
mined by this master oscillator and an internal frequency
divider, N
DIV
, programmable to eight settings from 1 to 128.
f
OUT
=
1MHz 50kΩ
•
, N = 1, 2, 4 …128
N
DIV
R
SET DIV
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Fixed-Frequency or Voltage-Controlled Operation
–
Fixed: Single Resistor Programs Frequency
with <1.5% Max Error
–
VCO: Two Resistors Set VCO Center
Frequency and Tuning Range
Frequency Range: 488Hz to 2MHz
2.25V to 5.5V Single Supply Operation
72µA Supply Current at 100kHz
500µs Start-Up Time
VCO Bandwidth >300kHz at 1MHz
CMOS Logic Output Sources/Sinks 20mA
50% Duty Cycle Square Wave Output
Output Enable (Selectable Low or Hi-Z When Disabled)
–55°C to 125°C Operating Temperature Range
Available in Low Profile (1mm) SOT-23 (ThinSOT™)
and 2mm × 3mm DFN Package
Low Cost Precision Programmable Oscillator
Voltage-Controlled Oscillator
High Vibration, High Acceleration Environments
Replacement for Fixed Crystal and Ceramic Oscillators
Portable and Battery-Powered Equipment
APPLICATIONS
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Optionally, a second resistor at the SET input provides
linear voltage control of the output frequency and can be
used for frequency modulation. A narrow or wide VCO
tuning range can be configured by the appropriate selec-
tion of the two resistors.
The LTC6990 includes an enable function that is synchro-
nized with the master oscillator to ensure clean, glitch-free
output pulses. The disabled output can be configured to
be high impedance or forced low.
For easy configuration of the LTC6990, download the
TimerBlox Designer tool at
www.linear.com/timerblox.
L,
LT, LTC and LTM, Linear Technology, TimerBlox and the Linear logo are registered
trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks
are the property of their respective owners. Protected by U.S. Patents, including 6342817,
6614313.
TYPICAL APPLICATION
Voltage Controlled Oscillator with 16:1 Frequency Range
1000
V
+
OE
OUT
f
OUT
(kHz)
LTC6990
GND
R
VCO
100k
R
SET
100k
V
+
C1
0.1µF
SET
DIV
6990 TA01a
VCO Transfer Function
f
OUT
=
1MHz
−
V
CTRL
• 0.5
MHz
V
750
V
+
500
V
CTRL
250
0
0
0.5
1
V
CTRL
(V)
1.5
2
6990 TA01b
6990fc
For more information
www.linear.com/LTC6990
1
LTC6990
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage (V
+
) to GND ........................................6V
Maximum Voltage on Any Pin
............................. (GND – 0.3V) ≤ V
PIN
≤ (V
+
+ 0.3V)
Operating Temperature Range (Note 2)
LTC6990C ............................................–40°C to 85°C
LTC6990I .............................................–40°C to 85°C
LTC6990H .......................................... –40°C to 125°C
LTC6990MP ....................................... –55°C to 125°C
Specified Temperature Range (Note 3)
LTC6990C ................................................ 0°C to 70°C
LTC6990I .............................................–40°C to 85°C
LTC6990H .......................................... –40°C to 125°C
LTC6990MP ....................................... –55°C to 125°C
Junction Temperature ........................................... 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10sec).................... 300°C
PIN CONFIGURATION
TOP VIEW
V
+
1
DIV 2
SET 3
7
6 OUT
5 GND
4 OE
OE 1
GND 2
SET 3
TOP VIEW
6 OUT
5 V
+
4 DIV
DCB PACKAGE
6-LEAD (2mm
×
3mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JA
= 64°C/W,
θ
JC
= 10.6°C/W
EXPOSED PAD (PIN 7) CONNECTED TO GND,
PCB CONNECTION OPTIONAL
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 150°C,
θ
JA
= 192°C/W,
θ
JC
= 51°C/W
ORDER INFORMATION
Lead Free Finish
TAPE AND REEL (MINI)
LTC6990CDCB#TRMPBF
LTC6990IDCB#TRMPBF
LTC6990HDCB#TRMPBF
LTC6990CS6#TRMPBF
LTC6990IS6#TRMPBF
LTC6990HS6#TRMPBF
TAPE AND REEL
LTC6990CDCB#TRPBF
LTC6990IDCB#TRPBF
LTC6990HDCB#TRPBF
LTC6990CS6#TRPBF
LTC6990IS6#TRPBF
LTC6990HS6#TRPBF
PART MARKING*
LDWX
LDWX
LDWX
LTDWW
LTDWW
LTDWW
PACKAGE DESCRIPTION
6-Lead (2mm × 3mm) Plastic DFN
6-Lead (2mm × 3mm) Plastic DFN
6-Lead (2mm × 3mm) Plastic DFN
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
SPECIFIED TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
–55°C to 125°C
LTC6990MPS6#TRMPBF LTC6990MPS6#TRPBF LTDWW
6-Lead Plastic TSOT-23
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
6990fc
2
For more information
www.linear.com/LTC6990
LTC6990
ELECTRICAL CHARACTERISTICS
SYMBOL
f
OUT
∆f
OUT
PARAMETER
Output Frequency
Frequency Accuracy (Note 4)
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. Test conditions are V
+
= 2.25V to 5.5V, OE = V
+
, DIVCODE = 0 to 15
(N
DIV
= 1 to 128), R
SET
= 50k to 800k, R
LOAD
= 5k, C
LOAD
= 5pF unless otherwise noted.
CONDITIONS
Recommended Range: R
SET
= 50k to 800k
Extended Range: R
SET
= 25k to 800k
Recommended Range
R
SET
= 50k to 800k
Extended Range
R
SET
= 25k to 800k
∆f
OUT
/∆T
∆f
OUT
/∆V
+
Frequency Drift Over Temperature
Frequency Drift Over Supply
Long-Term Frequency Stability
Period Jitter (Note 10)
V
+
= 4.5V to 5.5V
V
+
= 2.25V to 4.5V
(Note 11)
N
DIV
= 1
N
DIV
= 2
N
DIV
= 128
Duty Cycle
BW
t
S
Analog Inputs
V
SET
∆V
SET
/∆T
∆V
SET
/∆V
+
R
SET
V
DIV
∆V
DIV
/V
+
Power Supply
V
+
I
S
Operating Supply Voltage Range
Power-On Reset Voltage
Supply Current
R
SET
= 25k to 800k
R
L
= ∞, N
DIV
= 1, R
SET
= 50k
R
L
= ∞, N
DIV
= 1 R
SET
= 800k
R
L
= ∞, N
DIV
= 128, R
SET
= 50k
R
L
= ∞, N
DIV
= 128, R
SET
= 800k
V
+
= 5.5V
V
+
= 2.25V
V
+
= 5.5V
V
+
= 2.25V
V
+
= 5.5V
V
+
= 2.25V
V
+
= 5.5V
V
+
= 2.25V
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
MIN
0.488
0.488
TYP
MAX
1000
2000
UNITS
kHz
kHz
%
%
%
%
%/°C
%/V
%/V
ppm/√kHr
%
P-P
%
P-P
%
RMS
%
P-P
%
RMS
±0.8
±1.5
±2.2
±2.4
±3.2
±0.005
0.23
0.06
90
0.38
0.22
0.027
0.022
0.004
0.55
0.16
N
DIV
= 1, R
SET
= 25k to 800k
N
DIV
> 1, R
SET
= 25k to 800k
t
MASTER
= t
OUT
/N
DIV
l
l
47
48
50
50
0.4•f
OUT
6•t
MASTER
53
52
%
%
kHz
µs
Frequency Modulation Bandwidth
Frequency Change Settling Time
(Note 9)
Voltage at SET Pin
V
SET
Drift Over Temperature
V
SET
Drift Over Supply
Frequency-Setting Resistor
DIV Pin Voltage
DIV Pin Valid Code Range (Note 5)
DIV Pin Input Current
Deviation from Ideal V
DIV
/V
+
= (DIVCODE + 0.5)/16
Recommended Range
Extended Range
l
l
l
l
l
l
l
0.97
1.00
±75
–150
–7
1.03
V
µV/°C
µV/V
Ω
∆V
SET
/∆I
SET
V
SET
Droop with I
SET
50
25
0
800
800
V
+
±1.5
±10
kΩ
kΩ
V
%
nA
V
V
µA
µA
µA
µA
µA
µA
µA
µA
2.25
235
145
71
59
137
106
66
56
5.5
1.95
283
183
105
92
180
145
100
90
6990fc
For more information
www.linear.com/LTC6990
3
LTC6990
ELECTRICAL CHARACTERISTICS
SYMBOL
Digital I/O
OE Pin Input Capacitance
OE Pin Input Current
V
IH
V
IL
I
OUT(MAX)
V
OH
High Level OE Pin Input Voltage
Low Level OE Pin Input Voltage
OUT Pin Hi-Z Leakage
Maximum Output Current
High Level Output Voltage
(Note 7)
V
+
= 5.5V
V
+
= 3.3V
V
+
= 2.25V
V
OL
Low Level Output Voltage
(Note 7)
V
+
= 5.5V
V
+
= 3.3V
V
+
= 2.25V
t
PD
t
ENABLE
t
r
t
f
Output Disable Propagation Delay V
+
= 5.5V
V
+
= 3.3V
V
+
= 2.25V
Output Enable Time
Output Rise Time (Note 8)
N
DIV
≤ 2, t
OUT
= 1/f
OUT
N
DIV
≥ 4, t
MASTER
= t
OUT
/N
DIV
V
+
= 5.5V
V
+
= 3.3V
V
+
= 2.25V
V
+
= 5.5V
V
+
= 3.3V
V
+
= 2.25V
I
OH
= –1mA
I
OH
= –16mA
I
OH
= –1mA
I
OH
= –10mA
I
OH
= –1mA
I
OH
= –8mA
I
OL
= 1mA
I
OL
= 16mA
I
OL
= 1mA
I
OL
= 10mA
I
OL
= 1mA
I
OL
= 8mA
l
l
l
l
l
l
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. Test conditions are V
+
= 2.25V to 5.5V, OE = V
+
, DIVCODE = 0 to 15
(N
DIV
= 1 to 128), R
SET
= 25k to 800k, R
LOAD
= ∞, C
LOAD
= 5pF unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
2.5
OE = 0V to V
+
(Note 6)
(Note 6)
OE = 0V, DIVCODE ≥ 8, OUT = 0V to V
+
±20
5.45
4.84
3.24
2.75
2.17
1.58
5.48
5.15
3.27
2.99
2.21
1.88
0.02
0.26
0.03
0.22
0.03
0.26
17
26
44
t
PD
to t
OUT
t
PD
to 2•t
MASTER
1.1
1.7
2.7
1.0
1.6
2.4
0.04
0.54
0.05
0.46
0.07
0.54
l
l
l
MAX
UNITS
pF
±10
0.7•V
+
0.3•V
+
±10
nA
V
V
µA
mA
V
V
V
V
V
V
V
V
V
V
V
V
ns
ns
ns
µs
µs
ns
ns
ns
ns
ns
ns
Output Fall Time (Note 8)
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:
The LTC6990C is guaranteed functional over the operating
temperature range of –40°C to 85°C.
Note 3:
The LTC6990C is guaranteed to meet specified performance from
0°C to 70°C. The LTC6990C is designed, characterized and expected to
meet specified performance from –40°C to 85°C but it is not tested or
QA sampled at these temperatures. The LTC6990I is guaranteed to meet
specified performance from –40°C to 85°C. The LTC6990H is guaranteed
to meet specified performance from –40°C to 125°C. The LTC6990MP is
guaranteed to meet specified performance from –55°C to 125°C.
Note 4:
Frequency accuracy is defined as the deviation from the f
OUT
equation, assuming R
SET
is used to program the frequency.
Note 5:
See Operation section, Table 1 and Figure 2 for a full explanation
of how the DIV pin voltage selects the value of DIVCODE.
Note 6:
The OE pin has hysteresis to accommodate slow rising or falling
signals. The threshold voltages are proportional to V
+
. Typical values can
be estimated at any supply voltage using V
OE(RISING)
≈ 0.55 • V
+
+ 185mV
and V
OE(FALLING)
≈ 0.48 • V
+
– 155mV.
Note 7:
To conform to the Logic IC Standard, current out of a pin is
arbitrarily given a negative value.
Note 8:
Output rise and fall times are measured between the 10% and the
90% power supply levels with 5pF output load. These specifications are
based on characterization.
Note 9:
Settling time is the amount of time required for the output to settle
within ±1% of the final frequency after a 0.5x or 2x change in I
SET
.
Note 10:
Jitter is the ratio of the deviation of the period to the mean of the
period. This specification is based on characterization and is not 100% tested.
6990fc
4
For more information
www.linear.com/LTC6990
LTC6990
ELECTRICAL CHARACTERISTICS
Note 11:
Long-term drift of 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 nonlinear 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 266ppm at 90ppm/√kHr. Drift
without power applied to the device may be approximated as 1/10th of the
drift with power, or 9ppm/√kHr for a 90ppm/√kHr device.
TYPICAL PERFORMANCE CHARACTERISTICS
4
3
FREQUENCY ERROR (%)
2
1
0
–1
–2
–3
–4
10
V
+
= 3.3V, unless otherwise noted.
Frequency Error vs R
SET
T
A
= 25°C
GUARANTEED MAX
OVER TEMPERATURE
FREQUENCY ERROR (%)
Frequency Error
vs Supply Voltage
0.5
0.4
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
–0.4
1000
6990 G01
Frequency Error vs Temperature
1.5
1.0
V
+
= 3.3V
DIVCODE = 4
T
A
= 25°C
R
SET
= 800k
ERROR (%)
TYPICAL MAX
90% OF UNITS
TYPICAL MIN
GUARANTEED MIN
OVER TEMPERATURE
100
R
SET
(kΩ)
0.5
R
SET
= 50k
0.0
–0.5
–1.0
–1.5
–50
R
SET
= 800k
R
SET
= 267k
R
SET
= 200k
R
SET
= 50k
–0.5
2
3
4
5
SUPPLY VOLTAGE (V)
6
6990 G02
–25
0
25
50
75
TEMPERATURE (°C)
100
125
6990 G03
V
SET
vs I
SET
1.003
V
+
= 3.3V
T
A
= 25°C
1.003
V
SET
vs Supply Voltage
R
SET
= 200k
T
A
= 25°C
1.020
V
SET
vs Temperature
R
SET
= 200k
3 TYPICAL PARTS
1.015
1.010
1.002
V
SET
(V)
1.002
V
SET
(V)
V
SET
(V)
1.005
1.000
0.995
0.990
0.985
1.001
1.001
1.000
0
10
20
I
SET
(µA)
30
40
6990 G04
1.000
2
3
4
5
SUPPLY VOLTAGE (V)
6
6990 G05
0.980
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
6990 G06
6990fc
For more information
www.linear.com/LTC6990
5
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