a4231 general features
The a4231 is a proximity sensor integrated circuit to be used with a broad range of
inductive single-coiled proximity transducers in proximity detection applications
Monolithic IC in bipolar technology
User-adjustable sensing range by means of a single external resistor
User-adjustable hysteresis (0…15%)
5.5V…35V broad supply voltage range
Low-voltage operation possible using stabilised 4.5V…5.5V voltage source
Internal voltage regulator to improve immunity against fluctuations of supply
voltage
Broad operating temperature range: -25°C...90°C
Can work with a broad selection of inductive transducers
NPN open collector output with guaranteed sink current of 150mA
Output overload/over current protection
Integrated power-on and detect LED drivers
Normally open(NO)/normally closed(NC) select pin
Broad range of operating frequencies: 100kHz…1MHz
Output over current and short-circuit protection
Easy temperature compensation of proximity transducers
Package – QFN-24
example application schematic
min. 2.2uF/40V
electrolytic
C
F
100nF/6.3V
10%
Vcc
NO/NC
220nF/6.3V
20% ceramic
VCC
C
B
P_LED
R
F
Inductive
Transducer
L
C
RES
L
1
R
F
NO/NC
L
2
220nF/6.3V
20%
Rref
GND
R
H
a4231
D_LED
OutN
GND1
C
DET
C
OVL
RSN
R
S,N
1R6 5%
125mW
OutN
91kohm
Rhyst, 5%
(optional)
Cdet, 10%
(optional)
Covl, 10%
100nF/6.3V
Typical application schematic of a proximity sensor/detector
electrical characteristics
DC Characteristics
The typical values are given for V
CC
=24V and T
j
= 25°C unless otherwise specified.
#
1
2
3
4
5
6
Symbol
I
VCC,OFF
I
VCC,ON
V
SAT,OUT
I
LED
I
LKG
I
TH,OVL
Parameter
Supply current
Supply current
Output saturation voltage
LED current
Output leakage current
Overload threshold current*
1)
158
Conditions
Output inactive (off)
Output active (on)
I
OUT
=150mA
1.0
Min
Typ
3.8
8.5
0.50
1.2
<1
190
Max
4.8
12
0.70
1.6
20
220
Unit
mA
mA
V
mA
μA
mA
*
1)
–overload threshold current is the level of the output current which triggers the overload
protection circuit.
AC and Timing Characteristics
The typical values are given for V
CC
=24V and Tj = 25°C unless otherwise specified.
# Symbol Parameter
1
2
3
f
OSC
R
N
f
MAX
Operating frequency
Conditions
Defined by external LC
tank
Min
0.1
-200
5
kHz
C
DET
=33pF f
OSC
=100kHz
4
5
6
7
8
10
H
W
t
R
t
F
T
S,OVL
Hysteresis width
Output rise time
Output fall time*
2)
Sampling period in
overload mode
Input capacitance
Depends on R
HYST
Load=1kohm
Load=1kohm
Depends on C
OVL
50
50
Measured between Pin L1
and AC ground (Pin L2) for
f
OSC
=0.2…1MHz and |R
N
|
=2…100kohm
6
0
<1.5
<1
120
120
8.5
250
250
13
2
15
%
μs
μs
ms
ms
pF
Typ
Max
1.0
-2
Unit
MHz
kΩ
Negative resistance
R
N
= –2·R
F
+/-3%
between pin L1 and ground
Maximum switching
frequency*
1)
C
DET
=4.7pF, f
OSC
=600kHz
T
STARTUP
Startup time*
3)
C
IN
*
1)
– these are maximum switching frequencies of the IC itself; switching frequencies of sensors may be
higher than those given above,
2)
* – the fall time on leaving the start-up interval depends on the load used and can be as long as 10ms,
*
3)
– this is the maximum start-up time of the chip itself; this parameter does not reflect performance of a
sensor; during the start-up interval the output is inactive (OFF) regardless of the state of the NO/NC
pin.
嵌入式系统
