19-1390; Rev 0; 10/98
Low-Profile, 3V, 120µA,
IrDA Infrared Transceiver
General Description
The MAX3120 IrDA 1.2-compatible infrared transceiver
is optimized for battery-powered, space-constrained
applications. It consumes only 120µA while supporting
data rates up to 115kbps over a wide 3V to 5.5V oper-
ating range, and features a 10nA shutdown mode to
further extend battery life.
The MAX3120 reduces the space required for IrDA
applications by requiring a minimum of external compo-
nents: photodiode, infrared LED, and current-setting
resistor. Optical components are external to allow maxi-
mum flexibility in PC board design. The MAX3120 is
available in 8-pin µMAX and SO packages. The µMAX
package consumes half the board space of an 8-pin
SO.
Features
o
IrDA 1.2 Compatible: 2.4kbps to 115.2kbps
o
+3V to +5.5V Single-Supply Operation
o
Flexible Optics Selection and Layout
o
120µA Supply Current
o
10nA Shutdown Supply Current
o
200mA, High-Current Infrared LED Drive
MAX3120
Ordering Information
PART
MAX3120CUA
MAX3120CSA
MAX3120EUA
MAX3120ESA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
8 SO
8 µMAX
8 SO
Applications
IrDA Applications
Personal Digital Assistants (PDAs)
Palmtop Computers
Cell Phones
Hand-Held Equipment
Peripherals
Typical Operating Circuit
+3.3V
Pin Configuration
TOP VIEW
CS
SCLK
DIN
DOUT
V
CC
V
CC
SHDN
LED
TX
TXD
LEDC
MAX3100
RX
MAX3120
RXD
PINC
TXD
V
CC
GND
PINC
1
2
3
4
8
RXD
LEDC
PGND
SHDN
GND
GND
PGND
PIN
DIODE
MAX3120
7
6
5
µMAX/SO
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
Low-Profile, 3V, 120µA,
IrDA Infrared Transceiver
MAX3120
ABSOLUTE MAXIMUM RATINGS
(Referred to GND)
V
CC
...........................................................................-0.3V to +6V
TXD,
SHDN,
LEDC ...................................................-0.3V to +6V
RXD ............................................................-0.3V to (V
CC
+ 0.3V)
PGND ....................................................................-0.1V to +0.1V
PINC....................................................................................10mA
Continuous LEDC Current.................................................200mA
Repetitive Pulsed LEDC Current
(<90µs, duty cycle <20%) ..........................................500mA
Continuous Power Dissipation (T
A
= +70°C)
µMAX (derate 4.1mW/°C above +70°C) ....................330mW
SO (derate 5.88mW/°C above +70°C) .......................471mW
Operating Temperature Ranges
MAX3120C_A....................................................0°C to +70°C
MAX3120E_A.................................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
CC
= +3.0V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C and V
CC
= +3.3V.)
PARAMETER
DC CHARACTERISTICS
Supply Current
Shutdown Supply Current
LOGIC INPUTS (TXD,
SHDN)
Input Logic Threshold Low
Input Logic Threshold High
Input Leakage Current
Input Capacitance
LOGIC OUTPUT (RXD)
V
OL
Output Voltage
Output Rise and Fall Time
IR RECEIVER
Supported Data Rates
Equivalent Input Noise Current
Input Current Sensitivity
Ambient DC Current Rejection
Shutdown Time
Shutdown Disable Time
IR Receiver Output Pulse Width
V
OH
t
r
, t
f
I
SINK
= 200µA
I
SOURCE
= 100µA
C
LOAD
= 50pF
2.4
I
NOISE
(Note 2)
(Note 3)
V
CC
= 3.3V
V
CC
= 5.0V
Delay until I
CC
< 1µA
Delay until maximum IR receiver data rate is
valid
Data rate = 2.4kbps
Data rate = 115.2kbps
1
1
10
0.0002
100
375
10
300
90
8
6
V
CC
-
0.5
0.1
V
CC
-
0.05
50
115.2
0.4
V
ns
kbps
nA
RMS
mA
µA
µs
µs
µs
V
IL
V
IH
I
LEAK
C
IN
V
CC
= 3.3V
V
CC
= 5.0V
2.0
2.4
-1
2
1
0.8
V
V
µA
pF
I
CC
T
A
= +25°C,
SHDN
= V
CC
(Note 1)
120
0.01
200
1.0
µA
µA
I
CC(SHDN)
T
A
= +25°C,
SHDN
= GND (Note 1)
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Low-Profile, 3V, 120µA,
IrDA Infrared Transceiver
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.0V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C and V
CC
= +3.3V.)
PARAMETER
IR TRANSMITTER
Transmitter Rise Time
Transmitter Fall Time
Transmitter Output Resistance
Off-Leakage Current
SYMBOL
t
r
t
f
CONDITIONS
10% to 90% of 200mA drive current
90% to 10% of 200mA drive current
V
CC
= 3.3V
I
OUT
= 200mA
V
CC
= 5.0V
MIN
TYP
20
20
1.15
0.9
0.01
MAX
600
600
2.0
1.6
10
UNITS
ns
ns
Ω
µA
MAX3120
Note 1:
All supply current measurements are made under the following conditions: no load at all outputs, input voltages at GND or
V
CC
, no PIN diode input current.
Note 2:
Equivalent input current noise is calculated by dividing the output noise of the transimpedance amplifier by the midband
transimpedance gain.
Note 3:
Sensitivity is measured with an IrDA-compliant input signal, where the data rate is within the Supported Data Rate, rise/fall
times are less than 600ns, and pulse widths are between 1.41µs and 3/16 of the baud rate.
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
LED DRIVER
ON-RESISTANCE vs. TEMPERATURE
MAX3120 TOC01
SUPPLY CURRENT
vs. TEMPERATURE
MAX3120 TOC02
1.6
I
LEDC
= 100mA
1.4
V
CC
= 3.3V
140
130
SUPPLY CURRENT (µA)
V
CC
= 5V
120
R
LEDC
(Ω)
1.2
1.0
V
CC
= 5V
110
V
CC
= 3V
0.8
100
0.6
-40
-15
10
35
60
85
TEMPERATURE (°C)
90
-40
-15
10
35
60
85
TEMPERATURE (°C)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX3120 TOC03
LEDC VOLTAGE
vs. LEDC CURRENT
PULSED AT
20% DUTY CYCLE
MAX3120 toc04
135
130
SUPPLY CURRENT (µA)
125
600
500
400
V
LEDC
(mV)
V
CC
= 3.3V
300
200
V
CC
= 5V
100
0
120
115
110
105
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
100
150
200
250
300
350
400
LEDC CURRENT (mA)
_______________________________________________________________________________________
3
Low-Profile, 3V, 120µA,
IrDA Infrared Transceiver
MAX3120
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
AMBIENT PHOTODIODE CURRENT REJECTION
vs. SUPPLY VOLTAGE
MAX3120 TOC05
RXD OUTPUT PULSE WIDTH
vs. DISTANCE
TRANSMITTER POWER = 200mW/sr
INPUT PULSE WIDTH = 78µs
TEMIC BPV22NF
V
CC
= 3.3V
MAX3120 TOC06
RXD OUTPUT PULSE WIDTH
vs. DISTANCE
MAX3120 TOC07
450
400
CURRENT REJECTION (µA)
350
300
250
200
150
100
50
0
3.0
3.5
4.0
4.5
5.0
100
4.0
3.5
RXD PULSE WIDTH (µs)
3.0
2.5
2.0
1.5
1.0
TRANSMITTER POWER = 200mW/sr
INPUT PULSE WIDTH = 1.63µs
TEMIC BPV22NF
V
CC
= 3.3V
0
20
40
60
80
80
RXD PULSE WIDTH (µs)
60
40
20
0
5.5
0
20
40
60
80
100
SUPPLY VOLTAGE (V)
DISTANCE (cm)
100
DISTANCE (cm)
RXD OUTPUT
vs. INFRARED INPUT
MAX3120 toc08
RXD OUTPUT
vs. INFRARED INPUT
MAX3120 toc09
2V/div
RXD
OUTPUT
2V/div
RXD
OUTPUT
2V/div
INFRARED
INPUT
2V/div
INFRARED
INPUT
2µs/div
V
CC
= 3.3V, 115.2kbps AT 1cm DISTANCE,
TERMIC BPV22NF, TRANSMIT POWER 200mW/sr
100µs/div
V
CC
= 3.3V, 2400bps AT 1cm DISTANCE,
TERMIC BPV22NF, TRANSMIT POWER 200mW/sr
RXD OUTPUT
vs. INFRARED INPUT
MAX3120 toc10
RXD OUTPUT
vs. INFRARED INPUT
MAX3120 toc11
2V/div
RXD
OUTPUT
2V/div
RXD
OUTPUT
2V/div
INFRARED
INPUT
2V/div
INFRARED
INPUT
2µs/div
V
CC
= 3.3V, 115.2kbps AT 10cm DISTANCE,
TERMIC BPV22NF, TRANSMIT POWER 200mW/sr
100µs/div
V
CC
= 3.3V, 2400bps AT 10cm DISTANCE,
TERMIC BPV22NF, TRANSMIT POWER 200mW/sr
4
_______________________________________________________________________________________
Low-Profile, 3V, 120µA,
IrDA Infrared Transceiver
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
RXD OUTPUT
vs. INFRARED INPUT
RXD OUTPUT
vs. INFRARED INPUT
MAX3120
MAX3120 toc12
MAX3120 toc13
2V/div
RXD
OUTPUT
2V/div
RXD
OUTPUT
2V/div
INFRARED
INPUT
2V/div
INFRARED
INPUT
2µs/div
V
CC
= 3.3V, 115.2kbps AT 1m DISTANCE,
TERMIC BPV22NF, TRANSMIT POWER 200mW/sr
100µs/div
V
CC
= 3.3V, 2400bps AT 1m DISTANCE,
TERMIC BPV22NF, TRANSMIT POWER 200mW/sr
Pin Description
PIN
1
2
3
4
5
6
7
8
NAME
TXD
V
CC
GND
PINC
SHDN
PGND
LEDC
RXD
Supply Voltage
Ground. Connect anode of PIN diode to GND. Connect GND to PGND.
PIN Diode Cathode Input. Connect cathode of PIN diode to PINC.
Shutdown Input. Active low.
Power Ground. Ground for IR LED driver. Connect PGND to GND.
LED Driver Output. Connect cathode of IR-emitting LED to LEDC.
IR Receiver TTL/CMOS Data Output. Pulses low for IR input pulse.
FUNCTION
IR Transmitter TTL/CMOS Data Input. High = LED on.
Detailed Description
The MAX3120 is an IrDA 1.2-compatible infrared (IR)
transceiver. By selecting appropriate external optical
components (see
IR LED and PIN Photodiode Selection
section), the MAX3120 will operate at data rates of
2.4kbps to 115kbps at distances from 1cm to 1m.
Because of its low-noise design, the MAX3120
achieves a bit error rate (BER) below 10
-8
at maximum
data rates when used with the appropriate external
components. On-chip filtering rejects out-of-band
ambient light signals that would otherwise interfere with
IR communication. Also included in the MAX3120 is
a high-power LED driver capable of sinking 200mA. It
can drive most available IR LEDs at IrDA speeds of
2.4kbps to 115kbps.
Receiver
The MAX3120’s IR receiver amplifier reverse biases the
PIN diode by approximately 1.2V, and the PIN diode
converts pulses of IR light into pulses of current. The
input transimpedance (current-to-voltage) amplifier
then converts these current pulses into voltage pulses
of a useful magnitude. The MAX3120 filters the result-
ing output voltage pulses to remove low-frequency
ambient light interference and high-frequency circuit
noise. Finally, a high-speed comparator translates
these voltage pulses into usable CMOS output levels
(Figure 1).
_______________________________________________________________________________________
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