NJM2590V-TE1 NJR, NJM2590V-TE1 Datasheet - Page 10

• Manufacturer Part Number: NJM2590V-TE1
• Description: IC FM-IF DEMOD 455KHZ 14-SSOP
• Manufacturer: NJR

Specifications of NJM2590V-TE1

• Function: Demodulator
• Rf Frequency: 455kHz
• Voltage - Supply: 1.6 V ~ 5.5 V
• Package / Case: 14-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Supply: -
• Gain: -
• Noise Figure: -
• P1db: -
• Lo Frequency: -
• Other names: NJM2590V-TE1; NJM2590V-TE1TR

NJM2590/97
1.
2.
- 10 -
DESCRIPTION
FSK comparator (FSK COMP)
FSK comparator is a wave shaping circuit. When the demodulated FSK signal is weak or noisy, the computer may
fail to read this signal. To prevent the read-error, the wave shaping circuit will change this weak or noisy signal to the
correct signal. Pin 10 usually pulls up to power supply output voltage through an external high-valued resistor. This
external resistor can be connected to another power source within the limit of absolute maximum ratings.
Quick charge/ discharge circuit
The DC voltage of pin 4 is ordinarily equal to that of the demodulated FSK signal. When the initial state of power-up
turns into a steady state, the voltage of pin 4 will be late to come up to the reference voltage by reason of time
constant of an external capacitor and an internal resistor. At that time the wave shaped data may be failed to read
correctly. The quick charge/discharge circuit serves a useful function to shorten the rise time when power is turned
on. When power supply is hooked up to pin9 upon turning the power on, this circuit will charge/discharge the
external capacitor quickly to prevent read-error. Instead of the power supply, another power source can also be used
within the limit of the rated supply voltage.
During the high-speed charge/discharge circuit runs, DC level of FM demodulated signal may varies with frequency
shift or others. Even in such a case, the voltage of pin 4 follows the voltage of FM demodulated signal so that the
duty ratio of wave shaped output can keep constant.
V+
8
9
300kΩ
300kΩ
300kΩ
4
10uF
80kΩ
80kΩ
+
-
+
-
10
2kΩ
2.7kΩ
300Ω
100kΩ
V+
4
Ver.2004-08-25