
LTC6991
8
6991fb
BLOCK DIAGRAM (S6 package pin numbers shown)
6991 BD
PROGRAMMABLE
DIVIDER
FIXED
DIVIDER
÷ 1024
÷1, 8, 64, 512
4096, 215, 218, 221
MASTER OSCILLATOR
POR
OUTPUT
POLARITY
INPUT
POLARITY
DIGITAL
FILTER
4-BIT A/D
CONVERTER
POL BIT
R1
R2
DIV
V+
OUT
5
4
1
6
HALT OSCILLATOR
IF ISET < 500nA
MCLK
tMASTER =
1μs
50kΩ
VSET
ISET
=
+
–
ISET
VSET = 1V
+
– 1V
3
2
GND
SET
RST
RSET
DQ
R
V+
tOUT
PIN FUNCTIONS (DCB/S6)
GND (Pin 5/Pin 2): Ground. Tie to a low inductance ground
plane for best performance.
OUT (Pin 6/Pin 6): Oscillator Output. The OUT pin swings
from GND to V+ with an output resistance of approximately
30Ω. When driving an LED or other low impedance load
a series output resistor should be used to limit source/
sink current to 20mA.