U2535B Preamplifier for IR Remote Control Description The IC U2535B is a complete IR receiver for data communication. The PIN photodiode converts the transmitted IR telegram into electronic input signals. This is separated by a special input circuit. The characteristics (filter, gain) of the following amplifier are determined by exter-
nal components. The signal detector, consisting of a comparator, an integrator and a Schmitt trigger, forms the input signal to an output pulse that can be interfaced to a microcomputer.
Features
Applications
D Low current requirement (typical 260 mA/ 12 V) D Carrier frequencies 20 to 100 kHz D Supply voltages: 5 or 7 to 16 V with internal stabilization
D Keyless entry D Remote control D Wireless data transfer
D Filter characteristics and gain are specified by few external components
D Demodulator with Schmitt trigger D Open collector output
Ordering Information Extended Type Number U2535B-FP
Package SO8
Remarks
Block Diagram 95 9958
1 kW
5 VS Supply voltage for PIN diode
10 mF
+V
7 IN 8
+ –
1 A1
10 mF
4
+ –
6 GND
VS1
+VCC
– +
R1
2
3
A0
C3
C2
C1
Integrator
OSW
C3
R2
Figure 1. Block diagram
Rev. A2, 15-Oct-98
1 (6)
U2535B Pin Description
Pin 1
AI
1
8
IN
AO
2
7
VS1
C3
3
6
GND
OSW
4
2 3
4 5
VS
95 10323
Figure 2. Pinning
5
6 7 8
Symbol Function AI Inverting input of bandpass amplifier, pin connection for external filter function AO Output of bandpass amplifier C3 Capacitor at Pin 3 to reject (suppress) ripple during transmission, also functions as delay time for reference voltage of the comparator OSW Switching output Open collector output which switches with time delay and turns to LOW (transistor switched ON) when the signal is identified at Pin 2. VS Supply voltage The integrated Z-diode (typically 17 V) protects the circuit against positive voltage spikes GND Ground VS1 Unregulated supply voltage for 5 V operation IN Input connection for photodiode with regulated bias voltage
Absolute Maximum Ratings Reference point Pin 6, unless otherwise specified Parameters Supply-voltage range Pin 5 Supply currents: Pin 5 tp ≤ 250 ms Pin 5 Input voltages Pin 1 Pin 4 Pin 8 Output currents Pins 2 and 4 Junction temperature Storage-temperature range Ambient-temperature range
Symbol VS IS iS VA(I) V0(SW) VIN I0 Tj Tstg Tamb
Value –0.3 to +16 20 150 –0.3 to 5 –0.3 to 16 –0.3 to 5 ±5 125 –40 to +125 –40 to +105
Unit V mA mA V V V mA °C °C °C
Symbol RthJA
Value 180
Unit K/W
Thermal Resistance Parameters Junction ambient
2 (6)
Rev. A2, 15-Oct-98
Preliminary Information
U2535B Electrical Characteristics Tamb = 25°C, reference point Pin 6, test circuit, unless otherwise specified Parameters Supply currents Internal stabilization Maximum input current Low-level voltage Leakage current Input stage, amplifier Cut-off frequency Gain
Detector Threshold voltage Delay time Storage time
Test Conditions / Pins VS1 = 5 V, IIN = 0, Pin 7 Pin 5 VS = 12 V, IIN =0, VS = 12 V, IIN = 0, Pin 7 VS1 = 5 V, VIN = 0, Pin 8 VS1 = 5 V, IOL = 0.5 mA Pin 4 VS1 = 5 V, V0 = 12 V, Pin 4
Symbol IS1 IS VS1 –IIN VOL
Min. 140 200 4.9 0.8
Typ.
IOH
vi = 2 mVrms, f = 40 kHz f = 100 kHz td ≤ 200 ms, f = 40 kHz, Pin 2 f = 40 kHz, VA0 = 1 Vrms see figure 4 f = 40 kHz, VA0 = 1 Vrms see figure 4
fL fH
100
Gv Gv
47 46
Max. 200 320 5.4 1.2 0.2
Unit mA mA V mA V
1
mA
15
VA0 td
50
ts
100
kHz kHz
50 49
dB dB
150
mVrms
90
ms 150
ms
Test Circuit 95 9959
7 300 kW Ri Vi
5 C2
10 nF
8
+5 V 47 kW
U2535B
4
IIN
Output 6 1
2
3
300 kW R1 Ci
C3 100 nF
1 kW
22 nF
R2
Figure 3. Test circuit
Rev. A2, 15-Oct-98
3 (6)
U2535B 95 9960
V VAO
VL
td
ts 400 T
t
Figure 4. Waveforms for td and ts measurement
Application Circuit 10 mF
10 mF +12 V 1 kW
8
6
7
5
95 9961
U2535B
1
2
3
4
300 kW C1 680 pF R2 1.2 kW
mC
R1 C2 100 pF C3 47 nF
22 kW +
Figure 5. Application circuit
4 (6)
Rev. A2, 15-Oct-98
Preliminary Information
U2535B Bandpass Filter Design Center frequency fO
+ 2p ǸR
GAIN
1 C1
1
R2
C2
[ R R(C )C C ) 1
2
Bandwidth
R1 >> R2 C1 C2
y
1
1
[ 2p
2
C1 R1
)C
2
C1
BW
