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/
6991f
LTC6991
elecTrical characTerisTics
SYMBOL
t
OUT
f
OUT
∆f
OUT
∆f
OUT
/∆T
PARAMETER
Output Clock Period
Output Frequency
Frequency Accuracy (Note 4)
Frequency Drift Over Temperature
Frequency Drift Over Supply
Period Jitter (Note 10)
BW
t
S
Analog Inputs
V
SET
∆V
SET
/∆T
R
SET
V
DIV
∆V
DIV
/∆V
+
Voltage at SET Pin
V
SET
Drift Over Temperature
Frequency-Setting Resistor
DIV Pin Voltage
DIV Pin Valid Code Range (Note 5)
DIV Pin Input Current
Power Supply
V
+
I
S
Operating Supply Voltage Range
Power-On Reset Voltage
Supply Current
R
L
= ∞, R
SET
= 50k
R
L
= ∞, R
SET
= 100k
R
L
= ∞, R
SET
= 800k
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
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, RST = 0V, DIVCODE = 0 to 15
(N
DIV
= 1 to 2
21
), R
SET
= 50k to 800k, R
LOAD
= 5k, C
LOAD
= 5pF unless otherwise noted.
CONDITIONS
MIN
1.024m
29.1µ
29.1µHz ≤ f
OUT
≤ 977Hz
l
l
TYP
MAX
34,360
977
UNITS
Seconds
Hz
%
%
%/°C
%/V
%/V
ppm
RMS
ppm
RMS
Hz
Cycle
±0.8
±0.005
0.23
0.06
15
7
0.4 • f
OUT
1
0.97
50
0
1.00
±75
±1.5
±2.2
0.55
0.16
V
+
= 4.5V to 5.5V
V
+
= 2.25V to 4.5V
N
DIV
= 1
N
DIV
= 8
l
l
Frequency Modulation Bandwidth
Frequency Change Settling Time (Note 9)
1.03
800
V
+
±1.5
±10
V
µV/°C
kΩ
V
%
nA
V
V
µA
µA
µA
µA
µA
µA
Deviation from Ideal
V
DIV
/V
+
= (DIVCODE + 0.5)/16
l
l
2.25
135
105
100
80
65
55
5.5
1.95
170
135
130
105
100
85
6991f
LTC6991
elecTrical characTerisTics
SYMBOL
Digital I/O
PARAMETER
RST Pin Input Capacitance
RST Pin Input Current
High Level RST Pin Input Voltage
Low Level RST Pin Input Voltage
Output Output Current
High Level Output Voltage (Note 7)
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, RST = 0V, DIVCODE = 0 to 15
(N
DIV
= 1 to 2
21
), R
SET
= 50k to 800k, R
LOAD
=
∞,
C
LOAD
= 5pF unless otherwise noted.
CONDITIONS
MIN
TYP
2.5
RST = 0V to V
+
(Note 6)
(Note 6)
V
+
= 2.7V to 5.5V
V
+
= 5.5V
V
+
= 3.3V
V
+
= 2.25V
l
l
MAX
UNITS
pF
nA
V
V
mA
V
V
V
V
V
V
V
V
V
V
V
V
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
±10
0.7 • V
+
0.3 • V
+
5.45
4.84
3.24
2.75
2.17
1.58
±20
5.48
5.15
3.27
2.99
2.21
1.88
0.02
0.26
0.03
0.22
0.03
0.26
16
24
40
5
1.1
1.7
2.7
1.0
1.6
2.4
V
IH
V
IL
I
OUT(MAX)
V
OH
V
OL
Low Level Output Voltage (Note 7)
V
+
= 5.5V
V
+
= 3.3V
V
+
= 2.25V
t
RST
t
WIDTH
t
r
t
f
Reset Propagation Delay
Minimum Input Pulse Width
Output Rise Time (Note 8)
Output Fall Time (Note 8)
V
+
= 5.5V
V
+
= 3.3V
V
+
= 2.25V
V
+
= 3.3V
V
+
= 5.5V
V
+
= 3.3V
V
+
= 2.25V
V
+
= 5.5V
V
+
= 3.3V
V
+
= 2.25V
I
OUT
= –1mA
I
OUT
= –16mA
I
OUT
= –1mA
I
OUT
= –10mA
I
OUT
= –1mA
I
OUT
= –8mA
I
OUT
= 1mA
I
OUT
= 16mA
I
OUT
= 1mA
I
OUT
= 10mA
I
OUT
= 1mA
I
OUT
= 8mA
l
l
l
l
l
l
l
l
l
l
l
l
0.04
0.54
0.05
0.46
0.07
0.54
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 LTC6991C is guaranteed functional over the operating
temperature range of –40°C to 85°C.
Note 3:
The LTC6991C is guaranteed to meet specified performance from
0°C to 70°C. The LTC6991C 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 LTC6991I is guaranteed to meet
specified performance from –40°C to 85°C. The LTC6991H 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 RST 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
RST(RISING)
≈ 0.55 • V
+
+ 185mV
and V
RST(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 0.5× or 2× 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%
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