Type Ordering Code Package
TCA 3727 Q67000-A8302 P-DIP-20-6
TCA 3727 G Q67000-A8335 P-DSO-24-3
2-Phase Stepper-Motor Driver
Bipolar IC
TCA 3727
P-DSO-24-1, -3
Data Sheet 1 Rev. 2.0, 2004-10-01
Features
•2 × 0.75 amp. / 50 V outputs
• Integrated driver, control logic and current control
(chopper)
• Fast free-wheeling diodes
• Max. supply voltage 52 V
• Outputs free of crossover current
• Offset-phase turn-ON of output stages
• Z-diode for logic supply
• Low standby-current drain
• Full, half, quarter, mini step
Description
TCA 3727 is a bipolar, monolithic IC for driving bipolar
stepper motors, DC motors and other inductive loads that
operate on constant current. The control logic and power
output stages for two bipolar windings are integrated on
a single chip which permits switched current control of
motors with 0.75 A per phase at operating voltages up to
50 V.
The direction and value of current are programmed for each phase via separate control
inputs. A common oscillator generates the timing for the current control and turn-on with
phase offset of the two output stages. The two output stages in a full-bridge configuration
have integrated, fast free-wheeling diodes and are free of crossover current. The logic is
supplied either separately with 5 V or taken from the motor supply voltage by way of a
series resistor and an integrated Z-diode. The device can be driven directly by a
microprocessor with the possibility of all modes from full step through half step to mini
step.
TCA 3727
Data Sheet 2 Rev. 2.0, 2004-10-01
Figure 1 Pin Configuration TCA 3727 (top view)
IEP00696
21
Phase 2
Inhibit
GND
GND
Q21Q11
GND
GND
OSC
11
10 11
10
Q22
912
813
714
615
516
417
318
219
120
12
RR
V
S
Q12
V
L
Ι
Phase 1
Ι
Ι
20
Ι
Data Sheet 3 Rev. 2.0, 2004-10-01
TCA 3727
Figure 2 Pin Configuration TCA 3727 G (top view)
Table 1 Pin Definitions and Functions
Pin No. Function
1, 2, 19, 20
(1, 2, 23, 24)1)
Digital control inputs IX0, IX1 for the magnitude of the current of the
particular phase. See Table 2.
3Input Phase 1; controls the current through phase winding 1. On
H-potential the phase current flows from Q11 to Q12, on L-potential in
the reverse direction.
5, 6, 15, 16
(5, 6, 7, 8, 17,
18, 19, 20)1)
Ground; all pins are connected internally.
4Oscillator; works at approx. 25 kHz if this pin is wired to ground
across 2.2 nF.
8 (10)1) Resistor R1 for sensing the current in phase 1.
7, 10
(9, 12)1)
Push-pull outputs Q11, Q12 for phase 1 with integrated free-
wheeling diodes.
Q12 Q22
Q21
GND
GND
OSC
Phase 1 Phase 2
11
Ι
R1
IEP00898
10
Ι
GND
Q11
VS
++
L
V
2
R
Inhibit
Ι
20
Ι
21
GND
241
232
223
214
205
196
187
178
169
1510
1411
1312
GND
GND
GND
GND
TCA 3727
Data Sheet 4 Rev. 2.0, 2004-10-01
9 (11)1) Supply voltage; block to ground, as close as possible to the IC, with
a stable electrolytic capacitor of at least 10 µF in parallel with a
ceramic capacitor of 220 nF.
12 (14)1) Logic supply voltage; either supply with 5 V or connect to +VS
across a series resistor. A Z-diode of approx. 7 V is integrated. In both
cases block to ground directly on the IC with a stable electrolytic
capacitor of 10 µF in parallel with a ceramic capacitor of 100 nF.
11, 14
(13, 16)1)
Push-pull outputs Q22, Q21 for phase 2 with integrated free
wheeling diodes.
13 (15)1) Resistor R2 for sensing the current in phase 2.
17 (21)1) Inhibit input; the IC can be put on standby by low potential on this
pin. This reduces the current consumption substantially.
18 (22)1) Input phase 2; controls the current flow through phase winding 2. On
H-potential the phase current flows from Q21 to Q22, on L potential in
the reverse direction.
1) TCA 3727 G only
Table 2 Digital Control Inputs IX0, IX1
typical Imax with Rsense = 1 Ω, 750 mA
IX1 IX0 Phase Current Example of Motor Status
H H 0 No current
H L 1/3 Imax Hold
L H 2/3 Imax Set
LL
Imax Accelerate
Table 1 Pin Definitions and Functions (cont’d)
Pin No. Function
Data Sheet 5 Rev. 2.0, 2004-10-01
TCA 3727
Figure 3 Block Diagram TCA 3727
IEB00697
12 9
7
10
8
Q11
Q12
R
1
4
1
2
3
OSC
Function
Logic
+V
LS
V+
Ι
GND
Phase 1
Phase 1
Phase 1
5, 6, 15, 16
Phase 2
Phase 2
Phase 2
Logic
Function
Inhibit
18
19
20
17
2
R
Q22
Q21
13
11
14
Inhibit
10
11Ι
20Ι
21Ι
TCA 3727
Data Sheet 6 Rev. 2.0, 2004-10-01
Figure 4 Block Diagram TCA 3727 G
IEB00899
D14D13
D12D11
T14
T12
T13
T11
14 11
9
12
10
Q11
Q12
R
1
4
1
2
3
Oscillator
Functional
Logic
+V
LS
V+
Ι
11
GND
Phase 1
Phase 1
Phase 1
5-8, 17-19
Phase 2
Phase 2
Phase 2
Logic
Functional
Inhibit
22
23
24
21
2
R
Q22
Q21
15
13
16
T21
T23
T22
T24
D21 D22
D23 D24
Inhibit
10
Ι
Ι20
Ι21
Data Sheet 7 Rev. 2.0, 2004-10-01
TCA 3727
Attention: Stresses above those listed here may cause permanent damage to the
device. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
Table 3 Absolute Maximum Ratings
TA = -40 to 125 °C
Parameter Symbol Limit Values Unit Remarks
Min. Max.
Supply voltage VS052V–
Logic supply voltage VL06.5VZ-diode
Z-current of VLIL–50mA–
Output current IQ-1 1 A –
Ground current IGND -2 2 A –
Logic inputs VIXX -6 VL + 0.3 V IXX; Phase 1, 2;
Inhibit
R1, R2, oscillator input voltage VRX,
VOSC
-0.3 VL + 0.3 V –
Junction temperature Tj–
–
125
150
°C
°C
–
max. 10,000 h
Storage temperature Tstg -50 125 °C–
TCA 3727
Data Sheet 8 Rev. 2.0, 2004-10-01
Note: In the operating range, the functions given in the circuit description are fulfilled.
Table 4 Operating Range
Parameter Symbol Limit Values Unit Remarks
Min. Max.
Supply voltage VS550V–
Logic supply voltage VL4.5 6.5 V without series
resistor
Case temperature TC-40 110 °C measured on pin 5
Pdiss = 2 W
Output current IQ-1000 1000 mA –
Logic inputs VIXX -5 VLV IXX; Phase 1, 2;
Inhibit
Thermal Resistances
Junction ambient Rth ja – 56 K/W P-DIP-20-6
Junction ambient
(soldered on a 35 µm thick 20 cm2
PC board copper area)
Rth ja – 40 K/W P-DIP-20-6
Junction case Rth jc – 18 K/W measured on pin 5
P-DIP-20-6
Junction ambient Rth ja –75K/WP-DSO-24-3
Junction ambient
(soldered on a 35 µm thick 20 cm2
PC board copper area)
Rth ja –50K/WP-DSO-24-3
Junction case Rth jc – 15 K/W measured on pin 5
P-DSO-24-3
Data Sheet 9 Rev. 2.0, 2004-10-01
TCA 3727
Table 5 Characteristics
VS = 40 V; VL = 5 V; -25 °C ≤ Tj ≤ 125 °C
Parameter Symbol Limit Values Unit Test Condition
Min. Typ. Max.
Current Consumption
from +VSIS–0.20.5mAVinh = L
from +VSIS–1620mAVinh = H
IQ1/2 = 0, IXX = L
from +VLIL–1.73mAVinh = L
from +VLIL–1825mAVinh = H
IQ1/2 = 0, IXX = L
Oscillator
Output charging current IOSC – 110 – µA–
Charging threshold VOSCL –1.3–V–
Discharging threshold VOSCH –2.3–V–
Frequency fOSC 18 25 35 kHz COSC = 2.2 nF
Phase Current Selection (R1; R2)
Current Limit Threshold
No current Vsense n – 0 – mV IX0 = H; IX1 = H
Hold Vsense h 200 250 300 mV IX0 = L; IX1 = H
Setpoint Vsense s 460 540 620 mV IX0 = H; IX1 = L
Accelerate Vsense a 740 825 910 mV IX0 = L; IX1 = L
Logic Inputs (IX1; IX0; Phase x)
Threshold VI1.4
(H→L)
–2.3
(L→H)
V–
L-input current IIL -10 – – µAVI = 1.4 V
L-input current IIL -100 – – µAVI = 0 V
H-input current IIH ––10µAVI = 5 V
Standby Cutout (inhibit)
Threshold VInh
(L→H)
234V–
Threshold VInh
(H→L)
1.7 2.3 2.9 V –
Hysteresis VInhhy 0.3 0.7 1.1 V –
TCA 3727
Data Sheet 10 Rev. 2.0, 2004-10-01
Note: The listed characteristics are ensured over the operating range of the integrated
circuit. Typical characteristics specify mean values expected over the production
spread. If not otherwise specified, typical characteristics apply at TA = 25
°
C and
the given supply voltage.
Internal Z-Diode
Z-voltage VLZ 6.5 7.4 8.2 V IL = 50 mA
Power Outputs
Diode Transistor Sink Pair (D13, T13; D14, T14; D23, T23; D24, T24)
Saturation voltage Vsatl –0.30.6VIQ = -0.5 A
Saturation voltage Vsatl –0.51VIQ = -0.75 A
Reverse current IRl – – 300 µAVQ = 40 V
Forward voltage VFl –0.91.3VIQ = 0.5 A
Forward voltage VFl –11.4VIQ = 0.75 A
Diode Transistor Source Pair (D11, T11; D12, T12; D21, T21; D22, T22)
Saturation voltage VsatuC –0.91.2VIQ = 0.5 A;
charge
Saturation voltage VsatuD –0.30.7VIQ = 0.5 A;
discharge
Saturation voltage VsatuC –1.11.4VIQ = 0.75 A;
charge
Saturation voltage VsatuD –0.51VIQ = 0.75 A;
discharge
Reverse current IRu – – 300 µAVQ = 0 V
Forward voltage VFu –11.3VIQ = -0.5 A
Forward voltage VFu –1.11.4VIQ = -0.75 A
Diode leakage current ISL –12mAIF = -0.75 A
Table 5 Characteristics (cont’d)
VS = 40 V; VL = 5 V; -25 °C ≤ Tj ≤ 125 °C
Parameter Symbol Limit Values Unit Test Condition
Min. Typ. Max.
Data Sheet 11 Rev. 2.0, 2004-10-01
TCA 3727
Quiescent Current IS, IL versus
Supply Voltage VS
Output Current IQX versus
Junction Temperature Tj
Quiescent Current IS, IL versus
Junction Temperature Tj
Operating Condition:
•VL = 5 V
•VInh = H
•COSC = 2.2 nF
•Rsense = 1 Ω
• Load: L = 10 mH, R = 2.4 Ω
•fphase = 50 Hz
• mode: fullstep
0102030V50
0
10
20
30
40
mA
Ι
XX = H
= L
XX
Ι
j
T= 25 C
S
Ι
L
Ι
L
Ι
IED01655
VS
Ι
S,L
Ι
-25 0 25 50 75 100 C 150
j
T
QX
Ι
IED01657
0
200
800
400
600
mA
-25 0 25 50 75 100 150C
IED01656
XX
Ι
= H
= L
Ι
XX
= 40V
L
Ι
L
Ι
Ι
S
j
T
0
10
40
20
ΙΙ
S,
30
L
mA
VS
Data Sheet 12 Rev. 2.0, 2004-10-01
TCA 3727
Output Saturation Voltages Vsat
versus Output Current IQ
Typical Power Dissipation Ptot versus
Output Current IQ (non stepping)
Forward Current IF of Free-Wheeling
Diodes versus Forward Voltages VF
Permissible Power Dissipation Ptot
versus Case Temperature TC
0
00.5
0.2
0.4
0.6
1.0 V1.5
VF
Ι
F
0.8
A
Tj
1.0
= 25 C
Fl
VV
Fu
IED01167
P-DSO-24
P-DIP-20
Measured
at pin 5.
IED01660
0
6
8
W
tot
P
12
100-25 0 5025 75 C 175
Tc
10
4
2
125
Data Sheet 13 Rev. 2.0, 2004-10-01
TCA 3727
Input Characteristics of IXX, Phase X,
Inhibit
Oscillator Frequency fOSC versus
Junction Temperature Tj
Input Current of Inhibit versus Junction
Temperature Tj
VL= 5V
-6 -5 -2 3.9 2 6
IED01661
0.8
0.4
0
0.4
mA
IXX
Ι
0.8
V
VIXX
0.2
0.6
0.6
0.2
15
20
25
30
kHz
-25 0 25 50 75 100 125 C 150
VS
L
V
OSZ
C
= 40V
= 5V
= 2.2nF
OSC
f
j
T
IED01663
TCA 3727
Data Sheet 14 Rev. 2.0, 2004-10-01
Figure 5 Test Circuit
IES00706
1
2
3
17
20
19
18
12 9
7
10
14
11
413 8
GNDOSC
5, 6
15, 16
R
1
1Ω
R
2
Ω1
2.2 nF
Phase 1
Phase 2
Inhibit
V
L
V
S
Q11
Q12
Q21
Q22
TCA 3727
220 nF 100 F
µ
220 nF100 F
µ
Ι
L
Ι
S
Ι
GND
Ι
OSC
V
OSC
Ι
Q
Ι
Fu
Ι
R
Ι
Ru
Satl
-
-
V
Satu
V
Fu
V
S
-
V
Ι
V
Ι
Ι
Ι
Ι
ΙL
H
L
H
Ι
10
11
Ι
Ι
Ι
21
20
V
Fl
-
Sense
V
V
V
Sense
Data Sheet 15 Rev. 2.0, 2004-10-01
TCA 3727
Figure 6 Application Circuit
IES00707
1
2
3
17
20
19
18
12 3
7
10
14
11
4138
GNDOSC
5, 6
15, 16
R
1
1Ω
R
2
Ω1
2.2 nF
Micro
Controller
Ι
11
20
21
Phase 1
Phase 2
Inhibit
V
L
V
S
Q11
Q12
Q21
Q22
TCA 3727
M
220 nF 100 Fµ
+40 V+5 V
220 nF100 F
µ
10
Ι
Ι
Ι
TCA 3727
Data Sheet 16 Rev. 2.0, 2004-10-01
Figure 7 Full-Step Operation
t
IED01666
Accelerate Mode Normal Mode
acc
set
L
H
L
H
L
H
Ι
Phase 1
i
Q1
i
Ι
Ι
10
11
set
i
i
acc
i
set
i
acc
i
Q2
Ι
acc
set
i
Ι
21
20
Ι
H
H
L
L
L
H
Phase 2
t
t
t
t
t
t
t
Data Sheet 17 Rev. 2.0, 2004-10-01
TCA 3727
Figure 8 Half-Step Operation
t
t
t
t
t
t
IED01667
t
Accelerate Mode Normal Mode
t
21
Ι
20
Phase 2
Ι
L
L
H
H
H
L
Q2
Ι
-
-
-
iset
acc
i
i
set
acc
i
acc
i
Q1
Ι
-
Phase 1
set
i
set
i
L
acc
i
H
10
Ι
11
Ι
H
H
L
L
TCA 3727
Data Sheet 18 Rev. 2.0, 2004-10-01
Figure 9 Quarter-Step Operation
Data Sheet 19 Rev. 2.0, 2004-10-01
TCA 3727
Figure 10 Mini-Step Operation
H
L
H
L
H
L
i
set
i
hold
Ι
10
Ι
11
Phase 1
Ι
Q1
t
IED01665
acc
i
set
i
i
hold
acc
i
i
acc
set
i
set
hold
acc
hold
i
i
i
i
Ι
Q2
L
H
H
L
L
H
Ι
Ι
20
21
Phase 2
t
t
t
t
t
t
t
TCA 3727
Data Sheet 20 Rev. 2.0, 2004-10-01
Figure 11 Current Control
Osc
V
0
Ι
GND
VQ12 VS
+
0
S
+V
V
+S
+VS
t
t
VFU
sat 1
V
satu D
Vsatu C
V
phase x
phase x
Operating conditions:
V
R
L
S= 40 V
= 10 mH
= 20
IED01177
0
Ω
2.4 V
1.4 V
0
t
t
V
Q11
VQ22
VQ21
t
t
T
VL= 5 V
Inhibit
xx
V
V
Vphase x = H
= L
= H
Data Sheet 21 Rev. 2.0, 2004-10-01
TCA 3727
Figure 12 Phase Reversal and Inhibit
Inhibit
Oscillator
High Imped. Oscillator
High Imped.
Phase 1 Phase Changeover
High
Impedance
High
Impedance
High
Impe-
dance
Slow Current Decay
Fast Current Decay
IED01178
Ι
GND
V
Osc
2.3 V
1.3 V
0
L
L
Ι
N
0
t
V
Q11
satl
V
Fu
VV
satu C satu D
V
Fl
V
S
V
+
Phase 1
Ι
Fast
Current
Decay by
Inhibit
Slow
Current Decay
Operating Conditions:
V
S
= 40 V
V= 5 V
Ι
phase 1
L
phase 1
R
Ι
1X
= 20
= L;
V
+
S
Q12
V
= 10 mH
Ω
1X
Ι
= H
t
t
t
t
t
t
TCA 3727
Data Sheet 22 Rev. 2.0, 2004-10-01
Calculation of Power Dissipation
The total power dissipation Ptot is made up of
•saturation losses Psat (transistor saturation voltage and diode forward voltages),
•quiescent losses Pq (quiescent current times supply voltage) and
•switching losses Ps (turn-ON / turn-OFF operations).
The following equations give the power dissipation for chopper operation without phase
reversal. This is the worst case, because full current flows for the entire time and
switching losses occur in addition.
Ptot = 2 × Psat + Pq + 2 × Ps(1)
where
•Psat ≅ IN {Vsatl × d + VFu (1 - d) + VsatuC × d + VsatuD (1 - d)}
•Pq = Iq × VS + IL × VL
(2)
•IN = nominal current (mean value)
•Iq = quiescent current
•iD = reverse current during turn-on delay
•iR = peak reverse current
•tp = conducting time of chopper transistor
•tON = turn-ON time
•tOFF = turn-OFF time
•tDON = turn-ON delay
•tDOFF = turn-OFF delay
• T = cycle duration
•d = duty cycle tp/T
•Vsatl = saturation voltage of sink transistor (T3, T4)
•VsatuC = saturation voltage of source transistor (T1, T2) during charge cycle
•VsatuD = saturation voltage of source transistor (T1, T2) during discharge cycle
•VFu = forward voltage of free-wheeling diode (D1, D2)
•VS = supply voltage
•VL = logic supply voltage
•IL = current from logic supply
P
S
VS
T
------ iDtDON
×
2
---------------------- iDiR
+tON
×
4
------------------------------ IN
2
-----tDOFF tOFF
+++
⎩⎭
⎨⎬
⎧⎫
≅
Data Sheet 23 Rev. 2.0, 2004-10-01
TCA 3727
Figure 13
Figure 14
Dx3 Dx4
Dx1 Dx2
V
S
+
Tx3
Tx1
Tx4
Tx2
L
V
sense
sense
R
IES01179
IET01210
Voltage and
Current at
Chopper
Transistor
t
D
t
ON OFF
t
OFF
t
p
t
V
satl
V
SFu
V
+
i
D
i
R
Ι
N
Turn-ON Turn-OFF
+V
FuS
V
t
DON
TCA 3727
Data Sheet 24 Rev. 2.0, 2004-10-01
Application Hints
The TCA 3727 is intended to drive both phases of a stepper motor. Special care has
been taken to provide high efficiency, robustness and to minimize external components.
Power Supply
The TCA 3727 will work with supply voltages ranging from 5 V to 50 V at pin VS. As the
circuit operates with chopper regulation of the current, interference generation problems
can arise in some applications. Therefore the power supply should be decoupled by a
0.22 µF ceramic capacitor located near the package. Unstabilized supplies may even
afford higher capacities.
Current Sensing
The current in the windings of the stepper motor is sensed by the voltage drop across R1
and R2. Depending on the selected current internal comparators will turn off the sink
transistor as soon as the voltage drop reaches certain thresholds (typical 0 V, 0.25 V,
0.5 V and 0.75 V); (R1, R2 = 1 Ω). These thresholds are neither affected by variations of
VL nor by variations of VS.
Due to chopper control fast current rises (up to 10 A/µs) will occur at the sensing
resistors R1 and R2. To prevent malfunction of the current sensing mechanism R1 and R2
should be pure ohmic. The resistors should be wired to GND as directly as possible.
Capacitive loads such as long cables (with high wire to wire capacity) to the motor should
be avoided for the same reason.
Synchronizing Several Choppers
In some applications synchronous chopping of several stepper motor drivers may be
desirable to reduce acoustic interference. This can be done by forcing the oscillator of
the TCA 3727 by a pulse generator overdriving the oscillator loading currents
(approximately ≥ ±100 µA). In these applications low level should be between 0 V and
1 V while high level should be between 2.6 V and VL.
Optimizing Noise Immunity
Unused inputs should always be wired to proper voltage levels in order to obtain highest
possible noise immunity.
To prevent crossconduction of the output stages the TCA 3727 uses a special break
before make timing of the power transistors. This timing circuit can be triggered by short
glitches (some hundred nanoseconds) at the Phase inputs causing the output stage to
become high resistive during some microseconds. This will lead to a fast current decay
during that time. To achieve maximum current accuracy such glitches at the Phase
inputs should be avoided by proper control signals.
Data Sheet 25 Rev. 2.0, 2004-10-01
TCA 3727
Thermal Shut Down
To protect the circuit against thermal destruction, thermal shut down has been
implemented. To provide a warning in critical applications, the current of the sensing
element is wired to input Inhibit. Before thermal shut down occurs Inhibit will start to pull
down by some hundred microamperes. This current can be sensed to build a
temperature prealarm.
TCA 3727
Data Sheet 26 Rev. 2.0, 2004-10-01
Package Outlines
Figure 15 P-DIP-20-6 (Plastic Dual In-line Package)
GPD05587
You can find all of our packages, sorts of packing and others in our
Infineon Internet Page “Products”: http://www.infineon.com/products.Dimensions in mm
Data Sheet 27 Rev. 2.0, 2004-10-01
TCA 3727
Figure 16 P-DSO-24-3 (Plastic Dual Small Outline Package)
Lead width can be 0.61 max. in dambar area
Does not include plastic or metal protrusion of 0.15 max. per side
Index Marking
1.27
+0.15
0.35
15.6
1
24
2)
-0.4
1)
12
0.2
13
24x
0.1
2.65 MAX.
0.2
-0.1
2.45
-0.2
0.4
+0.8
10.3
±0.3
0.35 x 45˚
-0.2
7.6
1)
0.23 +0.09
MAX.8˚
1)
2)
GPS05144
You can find all of our packages, sorts of packing and others in our
Infineon Internet Page “Products”: http://www.infineon.com/products.Dimensions in mm
Template: ap_a5_vr_tmplt.fm / 2 / 2004-09-15
TCA 3727
Revision History: 2004-10-01 Rev. 2.0
Previous Version: 1.0, 1998-12-16
Page Subjects (major changes since last revision)
Edition 2004-10-01
Published by Infineon Technologies AG,
St.-Martin-Strasse 53,
81669 München, Germany
© Infineon Technologies AG 2004.
All Rights Reserved.
Attention please!
The information herein is given to describe certain components and shall not be considered as a guarantee of
characteristics.
Terms of delivery and rights to technical change reserved.
We hereby disclaim any and all warranties, including but not limited to warranties of non-infringement, regarding
circuits, descriptions and charts stated herein.
Information
For further information on technology, delivery terms and conditions and prices please contact your nearest
Infineon Technologies Office (www.infineon.com).
Warnings
Due to technical requirements components may contain dangerous substances. For information on the types in
question please contact your nearest Infineon Technologies Office.
Infineon Technologies Components may only be used in life-support devices or systems with the express written
approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the failure
of that life-support device or system, or to affect the safety or effectiveness of that device or system. Life support
devices or systems are intended to be implanted in the human body, or to support and/or maintain and sustain
and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other persons may
be endangered.