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 Keyless entry
D Carrier frequencies 20 to 100 kHz
D Remote control
D Supply voltages: 5 or 7 to 16 V with internal stabilization
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
Package
U2535B-FP
SO8
Remarks
Block Diagram 95 9958
1 kW
5 VS
+V 10 mF
Supply voltage for PIN diode 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. A3, 28-Sep-00
1 (6)
U2535B Pin Description
AI AO
1
8
2
IN
7
VS1
Pin
Symbol
1
AI
Inverting input of bandpass amplifier, pin connection for external filter function
2
AO
Output of bandpass amplifier
3
C3
Capacitor at Pin 3 to reject (suppress) ripple during transmission, also functions as delay time for reference voltage of the comparator
4
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.
5
VS
6
GND
7
VS1
Unregulated supply voltage for 5 V operation
8
IN
Input connection for photodiode with regulated bias voltage
U2535B C3
3
6
GND
OSW
4
5
VS
Figure 2. Pinning
Function
Supply voltage The integrated Z-diode (typically 17 V) protects the circuit against positive voltage spikes Ground
Absolute Maximum Ratings Reference point Pin 6, unless otherwise specified Symbol
Value
Unit
Supply-voltage range
Parameters Pin 5
VS
–0.3 to +16
V
Supply currents:
Pin 5 Pin 5
IS iS
20 150
mA mA
Input voltages
Pin 1 Pin 4 Pin 8
VA(I) V0(SW) VIN
–0.3 to 5 –0.3 to 16 –0.3 to 5
V V V
Output currents
Pins 2 and 4
I0
±5
mA
Tj
125
°C
Storage-temperature range
Tstg
–40 to +125
°C
Ambient-temperature range
Tamb
–40 to +105
°C
Symbol
Value
Unit
RthJA
180
K/W
tp ≤ 250 ms
Junction temperature
Thermal Resistance Parameters Junction ambient
2 (6)
Rev. A3, 28-Sep-00
U2535B Electrical Characteristics Tamb = 25°C, reference point Pin 6, test circuit, unless otherwise specified Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
Supply currents
VS1 = 5 V, IIN = 0, VS = 12 V, IIN =0,
Pin 7 Pin 5
IS1 IS
140 200
200 320
mA mA
Internal stabilization
VS = 12 V, IIN = 0,
Pin 7
VS1
4.9
5.4
V
Maximum input current
VS1 = 5 V, VIN = 0,
Pin 8
–IIN
0.8
1.2
mA
Low-level voltage
VS1 = 5 V, IOL = 0.5 mA Pin 4
VOL
0.2
V
Leakage current
VS1 = 5 V, V0 = 12 V, Pin 4
IOH
1
mA
15
kHz kHz
Input stage, amplifier Cut-off frequency Gain
vi = 2 mVrms, f = 40 kHz f = 100 kHz
fL fH
100
Gv Gv
47 46
50 49
dB dB
150
mVrms
90
ms
Detector Threshold voltage
td ≤ 200 ms, f = 40 kHz, Pin 2
Delay time
f = 40 kHz, VA0 = 1 Vrms see figure 4
td
50
Storage time
f = 40 kHz, VA0 = 1 Vrms see figure 4
ts
100
VA0
150
ms
Test Circuit 95 9959
7
+5 V
5 300 kW Ri Vi
C2
10 nF
8
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. A3, 28-Sep-00
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 mC C1 680 pF R2 1.2 kW
R1 C2 100 pF C3
22 kW
47 nF +
Figure 5. Application circuit
4 (6)
Rev. A3, 28-Sep-00
U2535B Bandpass Filter Design Center frequency fO +
1 C1
2p ǸR1
GAIN [
R2
C2
R1 C1 R 2 (C1 ) C2)
Bandwidth [
2p
R1 >> R2 C1 y C2
C1 ) C 2 R1 C1
BW
