ADuM1100 Datasheet, PDF (10/16 Pages) Analog Devices – iCoupler Digital Isolator

ADuM1100
1.7
1.6
–40؇C
1.5
+25؇C
1.4
1.3
+125؇C
1.2
1.1
3.0
3.5
4.0
4.5
5.0
5.5
INPUT SUPPLY VOLTAGE, V_DD1 (V)
TPC 7. Typical Input Voltage Switching Threshold,
Low-to-High Transition
1.4
–40؇C
+25؇C
1.3
1.2
+125؇C
1.1
1.0
0.9
0.8
3.0
3.5
4.0
4.5
5.0
5.5
INPUT SUPPLY VOLTAGE, V_DD1 (V)
TPC 8. Typical Input Voltage Switching Threshold,
High-to-Low Transition
APPLICATION INFORMATION
PC Board Layout
The ADuM1100 digital isolator requires no external interface
circuitry for the logic interfaces. A bypass capacitor is recom-
mended at the input and output supply pins. The input bypass
capacitor may most conveniently be connected between Pins 3
and 4 (Figure 2). Alternatively, the bypass capacitor may be located
between Pins 1 and 4. The output bypass capacitor may be con-
nected between Pins 7 and 8 or Pins 5 and 8. The capacitor value
should be between 0.01 µF and 0.1 µF. The total lead length
between both ends of the capacitor and the power supply pins
should not exceed 20 mm.
V_DD1
V₁ (DATA)
GND₁
V_DD2
(OPTIONAL)
V_O (DATA OUT)
GND₂
Figure 2. Recommended Printed Circuit Board Layout
INPUT (V_I)
OUTPUT (V_O)
t_PLH
t_PHL
50%
50%
Figure 3. Propagation Delay Parameters
Propagation Delay-Related Parameters
Propagation delay time describes the length of time it takes for a
logic signal to propagate through a component. Propagation delay
time to logic low output and propagation delay time to logic high
output refer to the duration between an input signal transition and
the respective output signal transition (Figure 3).
Pulse width distortion is the maximum difference between t_PLH and
t_PHL and provides an indication of how accurately the input signal’s
timing is preserved in the component’s output signal. Propagation
delay skew is the difference between the minimum and maximum
propagation delay values among multiple ADuM1100 compo-
nents operated at the same operating temperature and having
the same output load.
Depending on the input signal rise/fall time, the measured propa-
gation delay based on the input 50% level can vary from the true
propagation delay of the component (as measured from its input
switching threshold). This is due to the fact that the input threshold,
as is the case with commonly used optocouplers, is at a different
voltage level than the 50% point of typical input signals. This
propagation delay difference is given by
( )_{( )} ^∆LH ^{= t'}PLH ^{− t}PLH ^{= t}r ^{/ 0.8V}I ^0.5V1 ^−V_{ITH(L−H)}
( )_{( )} ^∆HL ^{= t'}PHL ^{− t}PHL ^{= t} f ^{/ 0.8V}I ^0.5V1 ^−V_{ITH(H−L)}
where:
t_PLH, t_PHL
= propagation delays as measured from the
input 50% level.
t ′_PLH, t ′_PHL
= propagation delays as measured from the
input switching thresholds.
t_r , t_f
= input 10% to 90% rise/fall time.
V_I
= amplitude of input signal (0 to V_I levels
assumed).
V_{ITH(L–H)}, V_{ITH(H–L)} = input switching thresholds.
V_{ITH(L–H)}
INPUT (V_I)
V_I ^⌬LH
t_PLH
OUTPUT (V_O)
t'_PLH
50%
⌬_HL
V_{ITH(H–L)}
t_PHL
50%
t'_PHL
Figure 4. Impact of Input Rise/Fall Time on Propagation Delay
–10–
REV. E