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Product Specification
DF0038B
IR Preamplifier for Remote Control System
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No: TDSPEC2006E Date: 2002.10.
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Tide Microelectronics DF0038B IR Preamplifier for Remote Control System
GENERAL DESCRIPTION
The DF0038B is a high performance infrared remote control preamplifier. Especially, it has excellent interference suppression capability. The infrared pulses arriving at the photodiode are treated by the trans-impedance amplifier and amplified by the auto-gain control amplifier, limiter amplifier, and band-pass filter. The following evaluation circuits, including the comparator, integrator, and schmitt-trigger, demodulate the transmitted digital signal. Reduction of sensitivity due to external interference is achieved by the short-time boost and long-time control circuits, which prevent interference voltages from affecting the output.
FEATURES
Only Two External Components Required Other than the Photodiode. Easy to Integrate into Module due to Small Chip Size. Minimized Chances of Malfunction Due to Ambient Light. Low Power Consumption. Center Frequency of Band Pass Filter Adjustable by an External Resistor. Microcomputer Compatible.
APPLICATIONS
IR Remote Control Receivers for Consumer Electronic Products, such as TVs, VCRs, VCD/DVD Players, Audio Devices, Air Conditioners, Electric Fans...etc.
PIN CONFIGURATONS
PIN DESCRIPTIONS
PIN 1: GND PIN 2: Vs PIN 3: OUT
Ground. Power supply pin. Output pin.
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Tide Microelectronics DF0038B IR Preamplifier for Remote Control System
BLOCK DIAGRAM
BLOCK DESCRIPTION
AUTOMATIC BIAS LEVEL CONTROL An ABLC (Automatic Bias Level Control) circuit is built into the input section to prevent the input level from being saturated by the external disturbing lights, such that this circuit is actuated by a strong external disturbing light to fix the bias level of the input terminal. TRANS-IMPEDANCE AMPLIFIER (T.I.A.) The Trans-impedance amplifier is an inverted amplifier with a sufficiently low input resistance, which amplifies the input photocurrent pulses. The resistance of the input at the signal frequency should not be too high. Otherwise the wanted signal would be lost to the junction capacitance of photodiode. AUTO-GAIN CONTROL AMPLIFIER (A.G.C.) The voltage gain of auto-gain control amplifier is controlled by the voltage at CA pin. In so doing, it supports the long-time interference suppression of the evaluation circuit. EVALUATION CIRCUIT The signal delivered from the band-pass filter is compared with a reference by the detector comparator. This reference is determined by the short-time boost circuit and the long-time control circuit. The inherent offset of the detector comparator and the reference determine the sensitivity of the evaluation circuit. The integrator is controlled by the above mentioned comparison. Its output is used to control the output stage after being processed through a schmitt-trigger. Use of the integrator keeps the output free of short-time interference. The ground of the evaluation circuit is routed out separately at pin 4, in order to minimize effect of the output switching edges. SHORT-TIME BOOST CIRCUIT (S.B.C.) The short-time boost circuit reduces the sensitivity of the evaluation circuit after reception of a signal. This prevents short-time interference from affecting the output. The reduction in sensitivity is achieved by boosting the reference input of the detector comparator.
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Tide Microelectronics DF0038B IR Preamplifier for Remote Control System
LONG-TIME CONTROL CIRCUIT (L.C.C.) The long-time control circuit improves the circuit's resistance to long-time interference by adapting the sensitivity of the evaluation circuit and the amplification of the AGC amplifier. Reduction of the evaluation circuit sensitivity is thereby achieved in the same way, as for the SBC, by raising the reference input of the detector comparator. The external capacitor C1 is charged as long as the signal is delivered from band pass filter and the voltage of C1 provides the necessary control voltage for AGC amplifier.
LIMITING VALUES
Supply Voltage ........................................................................................... 5.5V Input Voltage ........................................................................................... 5 Vp-p Operating Temperature Range ........................................................ -20 C~80 C Storage Temperature Range ....................................................... - 65 C~ 150 C
ELECTRICAL CHARACTERISTICS (VCC= 5V, Ta=25C, unless otherwise
specified.) PARAMETER
Supply Voltage Input Pin Voltage (1) Input Pin Voltage (2) Low Level Output Voltage High Level Output Voltage Voltage Gain BPF Characteristics 100 VP-P, 38KHz 100 VP-P, 28KHz, 35KHz, 41KHz, 48KHz (note 1) Input Impedance 0.5VP-P, 38KHz (note 2) 100 VP-P, 38KHz Detecting Ability (1) 600 S ON Time, 0.2 Duty Cycle 50mVP-P, 38KHz Detecting Ability (2) 600 S ON Time, 0.2 Duty Cycle TD2 540 670 800 S TD1 360 520 680 S RIN 4 11 K AQ 4 9 dB IIN=0 A IIN=100 A
TEST CONDITIONS
SYMBOL
Vcc VIN1 VIN2 VOL VOH AV
MIN.
4.5 3.8 1.5 4.70 76
TYP.
5.0 4.2 2.1 0.1 4.94 81
MAX.
5.5 4.4 2.7 0.3
UNIT
V V V V V dB
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Tide Microelectronics DF0038B
PARAMETER
Switch On Delay Time
IR Preamplifier for Remote Control System
TEST CONDITIONS
100 VP-P, 38KHz 600 S ON Time, 0.2 Duty Cycle 100 VP-P, 38KHz TON 100 250 400 S
SYMBOL
MIN.
TYP.
MAX.
UNIT
Switch Off Delay Time LCC Slew Rate Quiescent Current
600 S ON Time, 0.2 Duty Cycle C1=0.1 F
TOFF dv/dt ICC
150
220 0.8
400
S V/S
0.4
0.7
1.0
mA
NOTE 1: Ratio of the AC level at 35KHz and the AC level at 28KHz denotes AQ1. AQ1= 20log measured value (f = 35KHz) AQ2= 20log measured value (f = 41KHz) RIN=47K measured value (f = 28KHz) measured value (f = 48KHz) Ratio of the AC level at 41KHz and the AC level at 48KHz denotes AQ2. NOTE 2: Input level denotes VI and measured level denotes VX, then
TYPICAL CHARACTERISTICS
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Tide Microelectronics DF0038B IR Preamplifier for Remote Control System
DESIGN GUIDE
SETTING THE CENTER FREQUENCY OF BAND PASS FILTER Connect a resistor from pin 7 to VCC to set the center frequency of band pass filter. The center frequency will be lower if the resistor value is higher. The relationships between center frequency of band pass filter and the resistance of external resistor are tabulated as below: f0(KHz) R1(K) 33 130 36 118 37 114 38 110 40 104 56.8 72
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Tide Microelectronics DF0038B IR Preamplifier for Remote Control System
SETTING LCC CAPACITOR C1 With the transmitted data signal with duty cycle lower than 0.4 (average, during the whole transmission), the detection sensitivity is unchanged all the time. Otherwise, with the transmitted data signal with duty cycle higher than 0.4, the detection sensitivity will maintain unchanged for a proportional time period and gradually be reduced due to increasing control voltage at CA pin. Higher duty cycle enables more reduction of detection sensitivity in specific transmission time. Increasing the capacitance of C1 causes longer transmission time as duty cycle higher than the maximum allowable duty cycle. GROUNDING The AGND pin, DGND pin and all the external parts are recommended to be connected as much as possible to "one ground point" for good noise performance.
TYPICAL APPLICATION CIRCUIT
PACKAGE DIMENSIONS
3 LEAD PLASTIC (UNIT mm)
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Tide Microelectronics DF0038B IR Preamplifier for Remote Control System
Note: TIDE corporation assumes no responsibility for any errors which may appear in this document. reserves the right to change devices or specifications detailed herein at any time without notice. Attach: Revision History: Date
2002-10 2003-01
REV
1.0 2.0
Description Add typical application circuit 7
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