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 inter-
nal master oscillator frequency. The output frequency
is determined 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
n
n
n
n
n
n
n
n
n
n
Fixed-Frequency or Voltage-Controlled Operation
–
Fixed: Single Resistor Programs Frequency
with <2.2% 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)
–40°C to 125°C Operating Temperature Range
Available in Low Profile (1mm) SOT-23 (ThinSOT™)
and 2mm
×
3mm DFN Package
APPLICATIONS
n
n
n
n
n
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
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 selection 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.
The LTC6990 is available in the 6-lead SOT-23 (ThinSOT)
package or a 6-lead 2mm
×
3mm DFN.
L,
LT, LTC and LTM, Linear Technology and the Linear logo are registered trademarks of
Linear Technology Corporation. TimerBlox and ThinSOT are trademarks 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
LTC6990
GND
R
VCO
100k
SET
R
SET
100k
DIV
6990 TA01a
VCO Transfer Function
f
OUT
1MHz V
CTRL
• 0.5
MHz
V
750
f
OUT
(kHz)
V
+
V
+
C1
0.1μF
500
V
CTRL
250
0
0
0.5
1
V
CTRL
(V)
1.5
2
6990 TA01b
6990p
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
Specified Temperature Range (Note 3)
LTC6990C ................................................ 0°C to 70°C
LTC6990I .............................................–40°C to 85°C
LTC6990H .......................................... –40°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
EXPOSED PAD (PIN 7) CONNECTED TO GND,
PCB CONNECTION OPTIONAL
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 150°C,
θ
JA
= 230°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC6990CDCB#PBF
LTC6990IDCB#PBF
LTC6990HDCB#PBF
LTC6990CS6#PBF
LTC6990IS6#PBF
LTC6990HS6#PBF
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
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard 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/
6990p
2
LTC6990
ELECTRICAL CHARACTERISTICS
SYMBOL
f
OUT
Δf
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
Δf
OUT
/ΔT
Δf
OUT
/ΔV
+
Frequency Drift Over Temperature
Frequency Drift Over Supply
Period Jitter (Note 10)
V
+
= 4.5V to 5.5V
V
+
= 2.25V to 4.5V
N
DIV
= 1
N
DIV
= 2
N
DIV
= 128
Duty Cycle
BW
t
S
Analog Inputs
V
SET
ΔV
SET
/ΔT
ΔV
SET
/ΔV
+
Voltage at SET Pin
V
SET
Drift Over Temperature
V
SET
Drift Over Supply
Recommended Range
Extended Range
Deviation from Ideal V
DIV
/V
+
= (DIVCODE + 0.5)/16
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
%
P-P
%
P-P
%
RMS
%
P-P
%
RMS
±0.8
±1.5
±2.2
±2.4
±3.2
±0.005
0.23
0.06
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)
0.97
1.00
±75
–150
–7
1.03
V
μV/°C
μV/V
Ω
ΔV
SET
/ΔI
SET
V
SET
Droop with I
SET
Frequency-Setting Resistor
R
SET
V
DIV
ΔV
DIV
/V
+
Power Supply
V
+
I
S
Operating Supply Voltage Range
Power-On Reset Voltage
Supply Current
DIV Pin Voltage
DIV Pin Valid Code Range (Note 5)
DIV Pin Input Current
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
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
6990p
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
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
t
ENABLE
t
r
t
f
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.
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%
As time goes by, people are increasingly concerned about their own and their families' health. However, existing monitoring devices for individual vital signs have struggled to gain market share du...[详细]
我最近在《华尔街日报》看到一篇题为“我们需要能维修自己的电子小玩意儿的权利(We need the right to repair our gadgets)”的文章(参考原文：)，作者对于众多电子产品看来是“有计画的废弃(planned obsolescence)”之现象非常愤怒，认为大众应该要求电子产品可以被维修。 但实际的情况是，举例来说，家家都有的电视机如果故障了，修理费用可能...[详细]
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