LTC1069-6C Linear Technology, LTC1069-6C Datasheet - Page 5

• Manufacturer Part Number: LTC1069-6C
• Description: Single Supply/ Very Low Power/ Elliptic Lowpass Filter
• Manufacturer: Linear Technology

PIN
TYPICAL PERFORMANCE CHARACTERISTICS
AGND (Pin 1): Analog Ground. The quality of the analog
signal ground can affect the filter performance. For either
single or dual supply operation, an analog ground plane
surrounding the package is recommended. The analog
ground plane should be connected to any digital ground at
a single point. For single supply operation, Pin 1 should be
bypassed to the analog ground plane with a 0.47 F capaci-
tor or larger. An internal resistive divider biases Pin 1 to
0.4366 times the total power supply of the device (Figure
1). That is, with a single 5V supply, the potential at Pin 1
is 2.183V 1%. As the LTC1069-6 is optimized for single
supply operation, the internal biasing of Pin 1 allows
optimum output swing. The AGND pin should be buffered
if used to bias other ICs. Figure 2 shows the connections
for single supply operation.
U
Figure 1. Internal Biasing of the Analog Ground (Pin 1)
FUNCTIONS
U
3
0
5
4
2
1
1
2
3
4
0
Supply Current vs Supply Voltage
U
AGND
V
NC
V
+
IN
11.325k 8.775k
2
LTC1069-6
TOTAL SUPPLY VOLTAGE (V)
W
4
6
V
1069-6 F01
CLK
OUT
25 C
NC
V
U
–
8
8
7
6
5
85 C
– 40 C
10
12
14
1069-6 G12
16
V
the V
capacitor to an adequate analog ground. The filter’s power
supplies should be isolated from other digital or high
voltage analog supplies. A low noise linear supply is
recommended. Switching power supplies will lower the
signal-to-noise ratio of the filter. Unlike previous mono-
lithic filters, the power supplies can be applied in any
order, that is, the positive supply can be applied before the
negative supply and vice versa. Figure 3 shows the con-
nection for dual supply operation.
+
, V
–
–
Figure 2. Connections for Single Supply Operation
(Pins 2, 7): Power Supply Pins. The V
2.0
(Pin 7, if used) should be bypassed with a 0.1 F
4.5
4.0
2.5
80
60
40
20
0
Output Voltage Swing
vs Temperature
R
– 40
L
= 10k
STAR
SYSTEM
GROUND
–20
0.1 F
AMBIENT TEMPERATURE ( C)
V
V
0.47 F
IN
S
V
= SINGLE 5V
S
V
= SINGLE 3V
+
ANALOG GROUND PLANE
0
1
2
3
4
GROUND
DIGITAL
PLANE
V
V
20
AGND
V
NC
V
S
S
+
IN
= SINGLE 5V
= SINGLE 3V
LTC1069-6
40
60
V
CLK
OUT
NC
V
1069-6 G13
–
80
SOURCE
CLOCK
8
7
6
5
LTC1069-6
V
1k
OUT
1069-6 F02
+
(Pin 2) and
5