STMICROELECTRONICS L9705

L9705
DOUBLE QUAD CONTACT INTERFACE CIRCUIT
ADVANCE DATA
OPERATING DC SUPPLY VOLTAGE RANGE
5V TO 25V
SUPPLY OVERVOLTAGE PULSE UP TO 40V
VERY LOW STAND-BY QUIESCENT CURRENT, MAX 50µA
INTERNAL CLAMPING DIODES AT CONTACT
INPUTS TO Vs AND gnd WITH PULSE CURRENT CAPABILITY UP TO +50mA, -75mA
CHIP ENABLE FUNCTION AND TRISTATE
OUTPUTS FOR PARALLEL BUS CONNECTION
NOMINAL CONTACT CURRENTS OF 10mA
DEFINED WITH EXTERNAL CONTACT SERIES RESISTORS RIN1-8
CONTACT STATUS MONITORING BY
MEANS OF COMPARING THE RESISTANCE
AT CONTACT SENSE INPUTS WITH THE INTERNAL REFERENCE RESISTOR VALUE
RESISTANCE COMPARING WITH HYSTERESIS FOR HIGH NOISE IMMUNITY AND IMMUNITY TO GROUND AND BATTERY POTENTIAL DIFFERENCES
DIP 20
SO20L
ORDERING NUMBERS : L9705
DESCRIPTION
The L9705 is a bipolar monolithic integrated circuit for monitoring the status of up to four contacts connected to GND and up to four contacts
connected to the battery. The contact sense input
supply the contact current and perform the contact resistance comparison function.
At the output the contact status is translated into
a logical LOW level (contact closed) or logical
HIGh level (contact open).
BLOCK DIAGRAM
January 1992
1/8
This is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without notice.
L9705
ABSOLUTE MAXIMUM RATINGS
Symbol
Value
Unit
VSDC
DC Supply Voltage
Parameter
+26
V
+40
V
VSP
Peak Transient Supply Voltage (t < 400ms)
VCC
Logic Supply Voltage
IINDC
Input DC Current
IINP
Input Pulse (tp = 0 to 2ms; f< 0.2Hz; n = 25000)
IOUT
Output Current (VO = 0 to 5.5V)
VEN
Enable Input Voltage
Ptot
Total Power Dissipation (Tamb = 80°C)
Tj
7
V
+40
mA
-75 to 50
mA
internally limited
VCC +0.3V;-0.3V
V
875
420
mW
mW
max150
°C
DIP 20
SO 20
Junction Temperature Range
PIN CONNECTION (top view)
THERMAL DATA
Symbol
Description
R th j-amb
Thermal Resistance Junction-ambient
R th j-amb
Thermal Resistance Junction-ambient
2/8
DIP20
SO20L
Unit
°C/W
80
165
°C/W
L9705
ELECTRICAL CHARACTERISTICS (VS = 5 to 25V, VCC = 4.75 to 5.25V, Vbat -0.5V < VS ,< Vbat -1V ,
Tj = –40 to 150°C unless otherwise specified.)
Symbol
Parameter
Test Condition
Min.
Typ.
Unit
0.8
V
Enable Input Voltage LOW
(device activated)
VENH
Enable Input Voltage HIGH
2.4
VENh
Enable Input Threshold
Hysteresis
200
420
2.4V < VEN < VCC
0V < VEN < 0.8V
-5
-1
Output Voltage HIGH
0 < IOUT < 100µA
4
VCC -0.1
VCC
V
Output Current
OUT status = HIGH; VOUT = 0
0.5
2
mA
Output Voltage LOW
IOUT = -1mA
0.2
0.4
V
-5
-20
mA
0.5
µA
IEN
VOUTH
IOUT
VOUTL
Enable Input Current
-0.3
Max.
VENL
0.05
VCC
V
800
mV
5
µA
µA
Output Current
OUT status = LOW; VOUT = 5.5V
IOUT TS
Output Tristate Current
0 < VOUT < VCC
VIN 1,4
Input Voltage (device active)
EN = LOW; R IN = 1KΩ
VS -2
VIN 5,8
Input Voltage (device active)
EN = LOW; R IN = 1KΩ
0.4
1.5
2
V
Input VoltageDuring Clamp
(device disabled)
EN = HIGH; IIN = 30mA
IIN = -30mA
VS +0.3
-2
VS +1
-1
VS +2
-0.3
V
V
RIL 1,4
Input Resistor LOW Threshold
(note 1)
5V < VS <16V; ∆VGND≤ 0.1VS
∆VBAT≤ 0.1VBAT
1.8
4
KΩ
RIL 5,8
Input Resistor LOW Threshold
(note 1)
5V < VS <16V; ∆VGND≤ 0.1V S
∆VBAT≤ 0.1VBAT
1.8
4.8
KΩ
R IH 1,4
Input Resistor HIGH Threshold
(note 1)
5V < VS < 16V; ∆VGND≤ 0.1VS
∆VBAT≤ 0.1VBAT
5.3
20
KΩ
R IH 5,8
Input Resistor HIGH Threshold
(note 1)
5V < VS <16V; ∆VGND≤ 0.1V S
∆VBAT≤ 0.1VBAT
6.5
29
KΩ
RIL
Input Resistor Threshold Ratio
(note 1)
5V < VS <16V; ∆VGND≤ 0.1V S
∆VBAT≤ 0.1VBAT
0.65
0.75
0.85
R IH
Input Resistor Threshold Ratio
(note 1)
5V < VS <16V; ∆VGND≤ 0.1V S
∆VBAT≤ 0.1VBAT
0.65
0.75
0.85
IQC
Quiescent Current
EN = HIGH (tENH >20µs)
VS = 5 to 16V; Tj = -40 to 85°C
20
40
µA
IQS
Quiescent Current
all contact open
10
µA
IQS
Quiescent Current
all contact closed
35
µA
ΣIIN (2)
Quiescent Current
∆VBAT≤ 0.1VBAT
25
µA
IQC
Quiescent Current
EN = LOW
5
mA
IQS
Quiescent Current
EN = LOW
8
mA
tdo
Delay Time/Output (EN LOW to
Output Data Ready) (note 3)
C OUT ≤ 50pF
15+
3RIN*CIN
µs
tdTS
Delay Time/Tristate (EN HIGH
to Output Tristate) (note 3)
C OUT ≤ 50pF
10
µs
tdIO
Delay Time Input-Output (note 3)
EN = LOW; C OUT = 50pF
6
ms
IOUT
VIN
VS - 1.5 VS -0.4
V
NOTES:
1) The input resistor threshold value is a resistor value from the IN-pin to ground at which the corresponding output changes its status (fig.4)
2) ΣIIN is the sum of the IN5 to IN8 input currents.
3) The delay times are defined from the crossing point of 50% initiating signal amplitude to the crossing point of 50% output signal amplitude
3/8
L9705
Figure 1: Typical application diagram for the L9705 circuit. The current flowing in the arrow direction is
assumed positive. The external capacitors CIN and COUT represent the total wiring
capacitance at the corresponding pins.
FUNCTIONAL DESCRIPTION
The L9705 circuit monitors the status of the contacts which are connected through the series external resistors RIN to the contact sense input
pins. The contacts equivalent circuit is supposed
to be as shown in fig.2 for GND connected contacts (IN 1 to 4) and as shown in fig. 3 for VBAT
connected contacts (IN 5 to 8).
Figure 2: The contact sense input connection with the contact equivalent circuit for GND connected
contacts.
Figure 3: The contact sense input connection with the contact equivalent circuit for VBAT connected
contacts.
4/8
L9705
The L9705 circuit compares the input current with
the current through the internal reference resistor.
The device is designed to work with an external
input series resistor of RIN1-8 = 1KΩ. With this input resistor the contact current, when the contact
is closed and the device activated (EN =LOW) is:
IIN =
VS − 2V
,for GND contacts, (1)
1KΩ
IIN =
VBAT + ∆VBAT − 2V
, for VBAT contacts, (2)
1KΩ
For this calculation the limit value of the VS to VIN
and VIN saturation voltage of 2V was considered
so that the lowest limit value of IIN is calculated in
(1) and (2)
Figure 4: The output voltage as a function of the input resistance at the corresponding sense input.
The function of the circuit can be demonstrated
with the transfer characteristics, showing the output status as a function of the input resistor RI,
shown in figure 4. The input resistor is a sum of
the RIN and the contact resistance RCON or
RCOFF, for the closed contact:
RI = RIN + RCON, (3)
and for the open contact:
RI = RIN + RCOFF , (4)
The output goes HIGH when the input resistance
increases above 5.3KΩ (GND contacts) or 6.5KΩ
(VBAT contacts) and goes LOW, when the input
resistance decreases below 4KΩ (GND contacts)
or 4.8KΩ (VBAT contacts); these values are typical
values for the switching thresholds. The limit values of RI = 1.8KΩ (GND contacts) and RI =
1.8KΩ (VBAT contacts) for LOW and RI = 20KΩ
(GND contacts) and 29KΩ (VBAT contacts) for
HIGH implies that a contact with RCON = 100Ω ( at
IIN = 10mA) will be recognized as ON = LOW and
a contact with RCOFF = 19KΩ (GND contacts) or
28KΩ (VBAT contact) will be recognized as OFF =
HIGH.
These limits are valid within the supply voltage
range 6V < VS < 16V, the ground potential difference of ∆VGND = 0.1VS, the battery voltage potential difference of ∆VBAT < 0.1VBAT and the variation of the reverse battery protection diode D1
voltage from 0.5V to 1V.
The internal clamping diodes at the contact monitoring inputs together with the external contacts
series resistors RIN allows to withstand the transients at the contact connection.The contact series resistor RIN limits the input current at the transient.
The dynamic behaviour of the circuit is defined
with the times tdo and tdTS. When the contact is
open, the input capacitor CIN must be charged
through the resistor RIN. In this case the total delay time t do may be influenced also with the time
constant RINCIN.
The delay time tdTS, when disabling the device, is
defined only with the internal circuitry. In both
cases, output external capacitance less than
50pF is assumed, the internal output capacitance
of the tristate buffers are less than 5pF.
5/8
L9705
DIP20 PACKAGE MECHANICAL DATA
mm
DIM.
MIN.
a1
0.51
B
0.85
b
b1
TYP.
MAX.
MIN.
TYP.
MAX.
0.020
1.40
0.033
0.50
0.38
0.055
0.020
0.50
D
0.015
0.020
24.80
0.976
E
8.80
0.346
e
2.54
0.100
e3
22.86
0.900
F
7.10
0.280
I
5.10
0.201
L
Z
6/8
inch
3.30
0.130
1.27
0.050
L9705
SO20 PACKAGE MECHANICAL DATA
mm
DIM.
MIN.
TYP.
A
a1
inch
MAX.
MIN.
TYP.
2.65
0.1
0.104
0.3
a2
MAX.
0.004
0.012
2.45
0.096
b
0.35
0.49
0.014
0.019
b1
0.23
0.32
0.009
0.013
C
0.5
0.020
c1
45 (typ.)
D
12.6
13.0
0.496
0.512
E
10
10.65
0.394
0.419
e
1.27
0.050
e3
11.43
0.450
F
7.4
7.6
0.291
0.299
L
0.5
1.27
0.020
0.050
M
S
0.75
0.030
8 (max.)
7/8
L9705
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No
license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied.
SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics.
 1994 SGS-THOMSON Microelectronics - All Rights Reserved
SGS-THOMSON Microelectronics GROUP OF COMPANIES
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