easy to use and occupies very little PC board space. The
oscillator frequency is programmed by a single external
resistor (R
SET
). The LTC6900 has been designed for high
accuracy operation (≤1.5% frequency error) without the
need for external trim components.
The LTC6900 operates with a single 2.7V to 5.5V power
supply and provides a rail-to-rail, 50% duty cycle square
wave output. The CMOS output driver ensures fast rise/fall
times and rail-to-rail switching. The frequency-setting
resistor can vary from 10kΩ to 2MΩ to select a master
oscillator frequency between 100kHz and 20MHz (5V
supply). The three-state DIV input determines whether the
master clock is divided by 1, 10 or 100 before driving the
output, providing three frequency ranges spanning 1kHz
to 20MHz (5V supply). The LTC6900 features a proprietary
feedback loop that linearizes the relationship between R
SET
and frequency, eliminating the need for tables to calculate
frequency. The oscillator can be easily programmed using
the simple formula outlined below:
+
⎧
100, DIV Pin
=
V
⎛
20k
⎞
⎪
f
OSC
=
10MHz
• ⎜
, N
= ⎨
10, DIV Pin
=
Open
⎝
N•R
SET
⎟
⎠
⎪
1, DIV Pin
=
GND
⎩
L,
LT, LTC, LTM, Linear Technology and the Linear logo 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.
One External Resistor Sets the Frequency
1kHz to 20MHz Frequency Range
500μA Typical Supply Current, V
S
= 3V, 3MHz
Frequency Error ≤1.5% Max, 5kHz to 10MHz
(T
A
= 25°C)
Frequency Error ≤ 2% Max, 5kHz to 10MHz
(T
A
= 0°C to 70°C)
±40ppm/°C Temperature Stability
0.04%/V Supply Stability
50% ±1% Duty Cycle 1kHz to 2MHz
50% ± 5% Duty Cycle 2MHz to 10MHz
Fast Start-Up Time: 50μs to 1.5ms
100Ω CMOS Output Driver
Operates from a Single 2.7V to 5.5V Supply
Low Profile (1mm) ThinSOT™ Package
APPLICATIONS
n
n
n
n
n
n
n
n
n
Portable and Battery-Powered Equipment
PDAs
Cell Phones
Low Cost Precision Oscillator
Charge Pump Driver
Switching Power Supply Clock Reference
Clocking Switched Capacitor Filters
Fixed Crystal Oscillator Replacement
Ceramic Oscillator Replacement
TYPICAL APPLICATION
Clock Generator
5V
0.1μF
1
2
3
1kHz
≤
f
OSC
≤
20MHz
5
5V, N = 100
4
N=1
OPEN, N = 10
10000
1000
R
SET
(kΩ)
V
+
OUT
LTC6900
GND
SET
DIV
6900 TA01a
R
SET
vs Desired Output Frequency
÷100
÷10
÷1
10k
≤
R
SET
≤
2M
100
10
20k
f
OSC
= 10MHz •
N • R
SET
(
)
1
1k
100k
1M
10M
10k
DESIRED OUTPUT FREQUENCY (Hz)
100M
6900 TA01b
6900fa
1
LTC6900
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
V
+
1
GND 2
SET 3
4 DIV
5 OUT
Supply Voltage (V
+
) to GND .........................– 0.3V to 6V
DIV to GND .................................... –0.3V to (V
+
+ 0.3V)
SET to GND ....................................– 0.3V to (V
+
+ 0.3V)
Operating Temperature Range (Note 8)
LTC6900C ............................................– 40°C to 85°C
LTC6900I .............................................–40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
T
JMAX
= 150°C,
θ
JA
= 256°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC6900CS5#PBF
LTC6900IS5#PBF
TAPE AND REEL
LTC6900CS5#TRPBF
LTC6900IS5#TRPBF
PART MARKING*
LTZM
LTZM
PACKAGE DESCRIPTION
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°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/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 2.7V to 5.5V, R
L
= 5k, C
L
= 5pF Pin 4 = V
+
unless otherwise noted.
,
All voltages are with respect to GND.
SYMBOL
Δf
PARAMETER
Frequency Accuracy (Notes 2, 3)
CONDITIONS
V
+
= 5V
5kHz ≤ f ≤ 10MHz
5kHz ≤ f ≤ 10MHz, LTC6900C
5kHz ≤ f ≤ 10MHz, LTC6900I
1kHz ≤ f < 5kHz
10MHz < f ≤ 20MHz
5kHz ≤ f ≤ 10MHz
5kHz ≤ f ≤ 10MHz, LTC6900C
5kHz ≤ f ≤ 10MHz, LTC6900I
1kHz ≤ f < 5kHz
V
+
= 5V
V
+
= 3V
●
●
●
●
ELECTRICAL CHARACTERISTICS
MIN
TYP
± 0.5
±2
±2
± 0.5
MAX
±1.5
± 2.0
±2.5
UNITS
%
%
%
%
%
%
%
%
%
kΩ
kΩ
%/°C
V
+
= 3V
●
●
±1.5
± 2.0
±2.5
400
400
±2
20
20
± 0.004
0.04
0.1
0.2
0.6
300
0.1
R
SET
Δf/ΔT
Δf/ΔV
Frequency-Setting Resistor Range
Frequency Drift Overtemperature
(Note 3)
Frequency Drift Over Supply (Note 3)
Timing Jitter (Note 4)
|Δf| < 1.5%
R
SET
= 63.2k
V
+
= 3V to 5V, R
SET
= 63.2k
Pin 4 = V
+
, 20k ≤ R
SET
≤ 400k
Pin 4 = Open, 20k ≤ R
SET
≤ 400k
Pin 4 = 0V, 20k ≤ R
SET
≤ 400k
%/V
%
%
%
ppm/√kHr
Long-Term Stability of Output
Frequency
Duty Cycle (Note 7)
Pin 4 = V
+
or Open (DIV Either by 100 or 10)
Pin 4 = 0V (DIV by 1), R
SET
= 20k to 400k
●
●
49
45
50
50
51
55
%
%
6900fa
2
LTC6900
ELECTRICAL CHARACTERISTICS
SYMBOL
V
+
I
S
PARAMETER
Operating Supply Range
Power Supply Current
R
SET
= 400k, Pin 4 = V
+
, R
L
= ∞
f
OSC
= 5kHz
R
SET
= 20k, Pin 4 = 0V, R
L
= ∞
f
OSC
= 10MHz
V
IH
V
IL
I
DIV
V
OH
High Level DIV Input Voltage
Low Level DIV Input Voltage
DIV Input Current (Note 5)
High Level Output Voltage (Note 5)
Pin 4 = V
+
Pin 4 = 0V
V
+
= 5V
V
+
= 3V
V
OL
Low Level Output Voltage (Note 5)
V
+
= 5V
V
+
= 3V
t
r
OUT Rise Time
(Note 6)
V
+
= 5V
V
+
= 3V
t
f
OUT Fall Time
(Note 6)
V
+
= 5V
V
+
= 3V
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:
Frequencies near 100kHz and 1MHz may be generated using two
different values of R
SET
(see the Selecting the Divider Setting Resistor
paragraph in the Applications Information section). For these frequencies,
the error is specified under the following assumption: 20k < R
SET
≤ 200k.
Note 3:
Frequency accuracy is defined as the deviation from the
f
OSC
equation.
Note 4:
Jitter is the ratio of the peak-to-peak distribution of the period to
the mean of the period. This specification is based on characterization and
is not 100% tested. Also, see the Peak-to-Peak Jitter vs Output Frequency
curve in the Typical Performance Characteristics section.
I
OH
= – 1mA
I
OH
= –4mA
I
OH
= – 1mA
I
OH
= –4mA
I
OL
= 1mA
I
OL
= 4mA
I
OL
= 1mA
I
OL
= 4mA
Pin 4 = V
+
or Floating, R
L
= ∞
Pin 4 = 0V, R
L
= ∞
Pin 4 = V
+
or Floating, R
L
= ∞
Pin 4 = 0V, R
L
= ∞
Pin 4 = V
+
or Floating, R
L
= ∞
Pin 4 = 0V, R
L
= ∞
Pin 4 = V
+
or Floating, R
L
= ∞
Pin 4 = 0V, R
L
= ∞
V
+
= 5V
V
+
= 5V
V
+
= 5V
V
+
= 3V
V
+
= 5V
V
+
= 3V
The
l
denotes the specifications which apply over the full operating
,
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 2.7V to 5.5V, R
L
= 5k, C
L
= 5pF Pin 4 = V
+
unless otherwise noted.
All voltages are with respect to GND.
CONDITIONS
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
MIN
2.7
TYP
0.32
0.29
0.92
0.68
MAX
5.5
0.42
0.38
1.20
0.86
0.5
UNITS
V
mA
mA
mA
mA
V
V
μA
μA
V
V
V
V
V
+
– 0.4
2
–2
4.95
4.8
2.9
2.6
0.05
0.2
0.1
0.4
14
7
19
11
13
6
19
10
0.15
0.4
0.3
0.7
4
–4
4.8
4.5
2.7
2.2
V
V
V
V
ns
ns
ns
ns
ns
ns
ns
ns
Note 5:
To conform with the Logic IC Standard convention, current out of
a pin is arbitrarily given as a negative value.
Note 6:
Output rise and fall times are measured between the 10% and 90%
power supply levels. These specifications are based on characterization.
Note 7:
Guaranteed by 5V test.
Note 8:
The LTC6900C is guaranteed to meet specified performance from
0°C to 70°C. The LTC6900C 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 LTC6900I is guaranteed to meet
specified performance from –40°C to 85°C.
6900fa
3
LTC6900
TYPICAL PERFORMANCE CHARACTERISTICS
Frequency Variation vs R
SET
4
3
2
VARIATION (%)
1
0
–1
–2
–3
–4
1k
10k
100k
R
SET
(Ω)
1M
6900 G01
Frequency Variation Over
Temperature
1.00
1.0
R
SET
= 63.4k
÷1 OR ÷10 OR ÷100
0.9
0.8
JITTER (%
P-P
)
TYPICAL
HIGH
0.7
0.6
0.5
0.4
0.3
0.2
–0.75
–1.00
–40
–20
0
20
40
60
TEMPERATURE (°C)
80
6900 G02
Peak-to-Peak Jitter
vs Output Frequency
T
A
= 25°C
GUARANTEED LIMITS APPLY OVER
20kΩ ≤ R
SET
≤ 400kΩ
VARIATION (%)
TYPICAL HIGH
0.75
0.50
0.25
0
–0.25
–0.50
÷1, V
A
= 5V
÷1, V
A
= 3V
TYPICAL LOW
TYPICAL
LOW
÷10
÷100
1k
10k
100k
1M
OUTPUT FREQUENCY (Hz)
10M
6900 G03
0.1
0
Supply Current
vs Output Frequency
2.0
T
A
= 25°C
C
L
= 5pF
SUPPLY CURRENT (mA)
1.5
÷10, 5V
÷100, 5V
1.0
÷1, 5V
OUTPUT RESISTANCE (Ω)
140
Output Resistance
vs Supply Voltage
T
A
= 25°C
120
OUTPUT SOURCING CURRENT
100
80
0.5
÷100, 3V
0
0
1k
÷10, 3V
÷1, 3V
10M
6900 G04
60
OUTPUT SINKING CURRENT
40
2.5
3.0
3.5 4.0 4.5
5.0
SUPPLY VOLTAGE (V)
5.5
6.0
10k
100k
1M
OUTPUT FREQUENCY (Hz)
6900 G05
LTC6900 Output Operating at
20MHz, V
S
= 5V
V
+
= 5V, R
SET
= 10k, C
L
= 10pF
LTC6900 Output Operating at
10MHz, V
S
= 3V
V
+
= 3V, R
SET
= 20k, C
L
= 10pF
1V/DIV
1V/DIV
0V
0V
6900 G06
6900 G07
12.5ns/DIV
25ns/DIV
6900fa
4
LTC6900
PIN FUNCTIONS
V
+
(Pin 1):
Voltage Supply (2.7V ≤ V
+
≤ 5.5V). This supply
must be kept free from noise and ripple. It should be by-
passed directly to a ground plane with a 0.1μF capacitor.
GND (Pin 2):
Ground. Should be tied to a ground plane
for best performance.
SET (Pin 3):
Frequency-Setting Resistor Input. The value
of the resistor connected between this pin and V
+
deter-
mines the oscillator frequency. The voltage on this pin is
held by the LTC6900 to approximately 1.1V below the V
+
voltage. For best performance, use a precision metal film
resistor with a value between 10kΩ and 2MΩ and limit
the capacitance on this pin to less than 10pF
.
DIV (Pin 4):
Divider-Setting Input. This three-state input
selects among three divider settings, determining the value
of N in the frequency equation. Pin 4 should be tied to GND
for the ÷1 setting, the highest frequency range. Floating
Pin 4 divides the master oscillator by 10. Pin 4 should be
tied to V
+
for the ÷100 setting, the lowest frequency range.
To detect a floating DIV pin, the LTC6900 attempts to pull
the pin toward midsupply. Therefore, driving the DIV pin
high requires sourcing approximately 2μA. Likewise, driv-
ing DIV low requires sinking 2μA. When Pin 4 is floated,
it should preferably be bypassed by a 1nF capacitor to
ground or it should be surrounded by a ground shield to
prevent excessive coupling from other PCB traces.
OUT (Pin 5):
Oscillator Output. This pin can drive 5kΩ and/
or 10pF loads. Heavier loads may cause inaccuracies due
to supply bounce at high frequencies. Voltage transients,
coupled into Pin 5, above or below the LTC6900 power
supplies will not cause latchup if the current into/out of
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