D ata sh eet
A S1 7 2 0
S o l en o id / Va lv e D r iv e r w i th Cu r r e n t L im it at io n
1 General Description
The AS1720A is a low side current source providing an optimized
DC Operation for power saving and ultra low electromagnetic
radiation.
The AS1720B is a low side switch providing a PWM output, which
frequency is defined by an internal RC oscillator. The adjustable
PWM allows a fine control of the power delivered to the load.
Table 1. Standard Products
Model
AS1720A
AS1720B
Operation Mode
DC Current Source Operation
PWM Switching Operation
2 Key Features
Supply Range: +5V to +50V
Internal VDDA: 3.3V
Supply Current: 1 mA
Internal osc frequency: 30kHz
Fix delay: 136ms
Adjustable duty cycle: 20% – 90% (AS1720B only)
Adjustable energizing current: 10mA – 100mA
Adjustable hold current: 30% - 70% of energizing current
Current Limitation
Thermal shutdown: 150ºC
8-pin MLPD (2x2mm) Package
On request SOIC 8 Package (reduced temperature range -40°C
to +85°C)
The AS1720A and AS1720B can be set to provide a strong initial
closure current and is automatically switching to hold mode for
power saving. The initial DC current, the hold current and the duty
cycle of the PWM can be adjusted by external resistors. An internal
thermal sensor prevents damage of the circuit due to excessive
heating up.
Both devices are optimized for driving electromechanical devices
such as valves, solenoids relays, actuators and positioners.
3 Applications
The AS1720 is ideal for fluid and gas flow systems, industrial control,
electrical heaters, motor speed control.
Figure 1. AS1720 - Block Diagram
Vsupply: +5V to +50V
Internal VDDA typ. 3.3V
1
100nF
VDDHV
2
VDDA
LDO &
Ref Generator
AS1720
Delay
30kHz
Oscillator
R1
adjustable
Duty cycle
3
DUTY
L
R2
PWM &
Control
V
ref
VDDA
R
PU
Thermal
Shutdown
Current
Adjust
R
L
4
OUT
Free-
Wheeling
Diode
10nF
5
VSS
ENN
8
IE
6
IH
7
Off
On
R
IE
Energising Current adjust
R
IH
Hold Current adjust
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AS1720
Datasheet - P i n A s s i g n m e n t s
4 Pin Assignments
Figure 2. Pin Out (Top View)
VDDHV 1
VDDA 2
DUTY 3
OUT 4
8 ENN
AS1720
7 IH
6 IE
5 VSS
Pin Description
Table 2. Pin Descriptions
Pin Name
VDDHV
VDDA
DUTY
OUT
VSS
IE
IH
Pin Number
1
2
3
4
5
6
7
Description
Positive supply voltage
Internal supply of 3.3V (typ.)
Duty-Cycle.
By means of this pin the duty cycle can be adjusted between 20% and 90% during hold
phase. The duty cycle can be adjusted by a voltage source or an external resistor divider. Setting this
pin to V
DDA
the 50% duty cycle is selected automatically.
Current Source Output
Ground
Energize Current.
This pin defines the current during energize phase by means of a resistor.
Hold Current.
This pin defines the current during hold phase by means of a resistor.
Enable Not.
This pin can be used to switch on/off the current source (e.g. via a P), when the
AS1720 is always powered on.
Low during start-up: When VDDHV is applied, the device starts with the energise phase, followed by
the hold phase.
When the device is constantly powered on, it can be controlled by this pin.
High: The output current source is switched off.
Low: The device starts with the energise phase, followed by the hold phase.
ENN
8
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AS1720
Datasheet - A b s o l u t e M a x i m u m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in
Table 3
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
Section 6 Electrical Characteristics on page 4
is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Table 3. Absolute Maximum Ratings
Parameter
Electrical Parameters
VDDHV, OUT
VDDA, DUTY, ENN, IE, IH
Input Current (latch-up immunity)
Electrostatic Discharge
Electrostatic Discharge HBM
Temperature Ranges and Storage Conditions
Thermal Resistance
θ
JA
Junction Temperature T
J
Storage Temperature Range
-55
+36
+140
+150
ºC/W
ºC
ºC
The reflow peak soldering temperature (body
temperature) specified is in accordance with
IPC/
JEDEC J-STD-020 “Moisture/Reflow Sensitivity
Classification for Non-Hermetic Solid State
Surface Mount Devices”.
The lead finish for Pb-free leaded packages is
matte tin (100% Sn).
Non-condensing
Represents a max. floor life time of unlimited
Internally limited
+/- 1.5
kV
Norm: MIL 883 E method 3015
-0.9
-0.3
-100
+55
+5
100
V
V
mA
Norm: JEDEC 78 @85°C
Min
Max
Units
Notes
Package Body Temperature
+260
ºC
Humidity
Moisture Sensitive Level
5
1
85
%
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AS1720
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
V
DDHV
= 5V, V
SS
= 0V, Typical Values are at T
AMB
= +25ºC (unless otherwise specified). All limits are guaranteed. The parameters with min
and max values are guaranteed with production tests or SQC (Statistical Quality Control) methods.
Table 4. Electrical Characteristics
Symbol
T
AMB
T
J
Parameter
Operating Ambient Temperature
Operating Junction Temperature
Conditions
Min
-40
-40
Typ
Max
+85
+125
Units
°C
°C
valid for AS1720A & AS1720B
V
DDHV
V
DDA
I
DD
I
OUT_E
V
IH
V
IL
V
HYST
R
PU
Supply Voltage Range
Internal Supply
Supply Current
Output Energizing Current Range
Digital Input Threshold
Hysteresis
Pull-Up Resistor
Delay Time
T
SHDN
∆T
SHDN
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
1
5
no load
3.1
3.3
1
defined by R
IE
(see Figure 10 on page 7)
@ pin ENN
@ pin ENN
@ pin ENN
See Delay on page 6
10
2
V
SS
200
100
136
160
15
50
3.5
2
100
V
DDA
1.2
V
V
mA
mA
V
mV
kΩ
ms
ºC
ºC
only valid for AS1720A
V
OUT
k
I
OUT_H
Saturation Voltage, Sink
Transfer Value
Output Hold Current Range
1
1
I
OUT
= 100mA
R
IE
= 12kΩ, V
DDHV
= 5V to 50V, OUT =
1V to 40V
(see page 7)
defined by R
IH
(see Figure 10 on page 7)
1080
0.3 x
I
OUT_E
0.6
1200
1
1320
0.7 x
I
OUT_E
V
AΩ
mA
only valid for AS1720B
Minimum Duty Cycle
Maximum Duty Cycle
Internal Duty Cycle
V
trig
f
PWM
Trigger level to select internal
voltage divider
PWM Frequency
@ pin DUTY
25.5
15
83
20
90
50
V
DDA
30
34.5
25
95
%
%
%
V
kHz
1. The parameters are tested with proprietary test modes.
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AS1720
Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
7 Typical Operating Characteristics
V
SUPPLY
= 5V, R
IE
= 30kΩ, R
IH
= 120kΩ, T
AMB
= +25ºC (unless otherwise specified);
Figure 3. Duty Cycle vs. V
DUTY
90
80
Figure 4. PWM Frequency vs. Temperature
35
34
Duty Cycle (%)
70
60
50
40
30
20
0.5
0.75
1
1.25
1.5
1.75
2
2.25
2.5
PWM Frequency (kHz)
33
32
31
30
29
28
27
26
25
-40
-20
0
20
40
60
80
100 120
Voltage @ pin DUTY (V)
Figure 5. Supply Current vs. Supply Voltage
440
430
500
420
410
400
390
380
370
360
5
10
15
20
25
30
35
40
45
50
300
-40
Temperature (°C)
Figure 6. Supply Current vs. Temperature
550
I
DD
(µA)
I
DD
(µA)
450
400
350
-20
0
20
40
60
80
100 120
V
DDHV
(V)
Figure 7. Transfer Function vs. Supply Voltage
1400
1350
Temperature (°C)
Figure 8. Transfer Function vs. Temperature
1400
1350
Transfer Value k
1250
1200
1150
1100
1050
5
10
15
20
25
30
35
40
Transfer Value k
1300
1300
1250
1200
1150
1100
1050
-40 -20
0
20
40
60
80
100 120
V
DDHV
(V)
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Temperature (°C)
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