LTC6990CDCB#PBF Linear Technology, LTC6990CDCB#PBF Datasheet - Page 13

• Manufacturer Part Number: LTC6990CDCB#PBF
• Description: IC, VOLTAGE CONTROLLED OSCILLATOR, DFN-6
• Manufacturer: Linear Technology

Specifications of LTC6990CDCB#PBF

• Clock External Input: Yes
• Supply Voltage Range: 2.25V To 5.5V
• Digital Ic Case Style: DFN
• No. Of Pins: 6
• Operating Temperature Range: 0°C To +70°C
• Frequency: 2MHz
• Msl: MSL 1 - Unlimited
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

OPERATION
Changing DIVCODE After Start-Up
Following start-up, the A/D converter will continue
monitoring V
be recognized slowly, as the LTC6990 places a priority on
eliminating any “wandering” in the DIVCODE. The typical
delay depends on the difference between the old and
new DIVCODE settings and is proportional to the master
oscillator period.
A change in DIVCODE will not be recognized until it is
stable, and will not pass through intermediate codes. A
digital fi lter is used to guarantee the DIVCODE has settled
to a new value before making changes to the output. Then
the output will make a clean (glitchless) transition to the
new divider setting.
t
DIVCODE
1V/DIV
1V/DIV
OUT
DIV
V
R
+
Figure 5. DIVCODE Change from 5 to 2
SET
= 16 • (ΔDIVCODE + 6) • t
= 3.3V
DIV
= 200k
for changes. Changes to DIVCODE will
576μs
100μs/DIV
MASTER
6990 F05
Start-Up Time
When power is fi rst applied to the LTC6990 the power-on
reset (POR) circuit will initiate the start-up time, t
The OUT pin is fl oated (high-impedance) during this time.
The typical value for t
depending on the master oscillator frequency (indepen-
dent of N
The start-up time may be longer if the supply or DIV
pin voltages are not stable. For this reason, it is recom-
mended to minimize the capacitance on the DIV pin so it
will properly track V
t
START(TYP)
1V/DIV
1V/DIV
OUT
V
DIV
+
V
DIVCODE = 4
R
+
SET
):
= 2.5V
= 50k
= 500 • t
Figure 6. Typical Start-Up
OUTPUT CONNECTED
TO 1.25V THROUGH 25k
TO SHOW Hi-Z
+
.
START
MASTER
470μs
100μs/DIV
ranges from 0.5ms to 8ms
LTC6990
6990 F06
13
START
6990f
.