Dual SPM Detector
Page 6 of 16
MX641 Preliminary Information
3. External Components
V
DD
XTAL/CLOCK
If you use a Clock Pulse input:
- Remove Xtal (X
1
)
- Connect Pin 1 to V
DD
- Do not short Pins 3 & 4
- Input clock pulses to CLOCK IN
See Figure 3
V
DD
XTAL/CLOCK
X1
CLOCK IN
XTAL
OUT
CLOCK
IN
OUTPUT ENABLE
CH2 OUTPUT
CH1 OUTPUT
V
BIAS
CH1 AMP OUT
C3
C4
CH1 AMP IN (-)
R2
R1
R3
CH1 AMP IN (+)
R4
R8
C2
V
SS
1
2
3
4
5
6
7
8
9
10
11
12
MX641
24
23
22
21
20
19
18
17
16
15
14
13
V
DD
C1
SYSTEM SELECT
SERIAL DATA
SERIAL CLOCK
CHIP SELECT
PRESET LEVEL
OUTPUT SELECT
CH2 AMP OUT
R7
CH2 AMP IN (-)
C5
R6
R5
C6
CH2 AMP IN (+)
Figure 2: Recommended External Components
R1
R2
R3
R4
R5
R6
R7
R8
Note 1
Note 1
Note 1
Note 1
68k
Ω
68k
Ω
750k
Ω
750k
Ω
68k
Ω
68k
Ω
750k
Ω
750k
Ω
± 1%
±1%
±1%
±1%
± 1%
± 1%
±1%
±1%
C1
C2
C3
C4
C5
C6
X1
Note 2, 3
1.0µF
1.0µF
270pF
270pF
270pF
270pF
3.579545MHz
±20%
±20%
±5%
±5%
±5%
±5%
Table 2: Recommended External Components
Note:
1. Fixed Sensitivity Setting: when calculating/selecting gain components, R3, R4, R7 and R8 should
always be greater than or equal to 100k
Ω
.
2. For best results, a crystal oscillator design should drive the clock inverter input with signal levels of at
least 40% of V
DD
, peak to peak. Tuning fork crystals generally cannot meet this requirement. To
obtain crystal oscillator design assistance, consult your crystal manufacturer.
3. The on-chip crystal circuitry includes a feedback resistor (nominally 2M
Ω
) between pins 1 & 2 and load
capacitors on pins 1 & 2 (nominally 10pF each, excluding package and board parasitics).
ã
2001 MX-COM, Inc.
www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054
Doc. # 20480115.004
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
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