LTC6905IS5-133 查看數據表（PDF） - Linear Technology
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LTC6905IS5-133 Datasheet PDF : 8 Pages
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LTC6905-XXX Series
PI FU CTIO S
V+ (Pin 1): Voltage Supply (2.7V ≤ V+ ≤ 5.5V). This supply
must be kept free from noise and ripple. It should be
bypassed directly to the GND (Pin 2) with a 0.1µF capacitor
or higher.
GND (Pin 2): Ground. Should be tied to a ground plane for
best performance.
OE (Pin 3): Output Enable. Pull to V+ or leave floating to
enable the output driver (Pin 5). Pull low to disable the
output. The output is disabled asynchronously. Pulling OE
pin low will immediately disable the output. Pulling the OE
pin high will bring the output high on the next low to high
transition of the clock. This eliminates pulse slivers.
DIV (Pin 4): Divider-Setting Input. This three-state input
selects among three divider settings. Pin 4 should be tied
to V+ for the ÷1 setting, the highest frequency range. Float-
ing Pin 4 divides the master oscillator by 2. Pin 4 should
be tied to GND for the ÷4 setting, the lowest frequency range.
To detect a floating DIV pin, the LTC6905 attempts to pull
the pin toward midsupply. This is realized with two internal
current sources, one tied to V+ and Pin 4 and the other one
tied to ground and Pin 4. Therefore, driving the DIV pin high
requires sourcing approximately 15µA. Likewise, driving
DIV low requires sinking 15µA. When Pin 4 is floated, it
should be bypassed by a 1nF capacitor to ground or it should
be surrounded by a ground shield to prevent excessive cou-
pling from other PCB traces.
OUT (Pin 5): Oscillator Output. This pin can drive 5kΩ
and/or 5pF loads. For heavier loads, refer to the Applica-
tions Information section.
BLOCK DIAGRA
V+
1
RSET IRES
VR(EVS+
=
–
1V ±5%
VSET)
+
GAIN = 1
–
MASTER OSCILLATOR
–
+– VBIAS
IRES
+
2 GND
3
OE
PROGRAMMABLE
fOSC
=
fMO
N
OUT
DIVIDER
5
(N = 1, 2 OR 4)
DIVIDER
SELECT
fMO
THREE-STATE
INPUT DETECT
V+
15µA
DIV
4
15µA
GND
6905x BD
Table 1. LTC6905-XXX Frequency Settings
DIV SETTING LTC6905-133 LTC6905-100
V+
133.33MHz
100MHz
OPEN
66.66MHz
50MHz
GND
33.33MHz
25MHz
LTC6905-96
96MHz
48MHz
24MHz
LTC6905-80
80MHz
40MHz
20MHz
6905xf
5
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