ADUM5000ARWZ-RL Analog Devices Inc, ADUM5000ARWZ-RL Datasheet - Page 11

• Manufacturer Part Number: ADUM5000ARWZ-RL
• Description: Isolated DC/DC Converter
• Manufacturer: Analog Devices Inc
• Series: IsoPower®, iCoupler®r

Specifications of ADUM5000ARWZ-RL

• Design Resources: USB Cable Isolator Circuit (CN0159)
• Inputs - Side 1/side 2: 2/0
• Number Of Channels: 2
• Isolation Rating: 2500Vrms
• Voltage - Supply: 2.7 V ~ 5.5 V
• Output Type: Logic
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Operating Temperature: -40°C ~ 105°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Rate: -
• Propagation Delay: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
The dc-to-dc converter section of the ADuM5000 works on
principles that are common to most switching power supplies.
It has a secondary side controller architecture with isolated pulse-
width modulation (PWM) feedback. V
an oscillating circuit that switches current into a chip-scale air
core transformer. Power transferred to the secondary side is
rectified and regulated to either 3.3 V or 5 V. The secondary (V
side controller regulates the output by creating a PWM control
signal that is sent to the primary (V
iCoupler data channel. The PWM modulates the oscillator circuit
to control the power being sent to the secondary side. Feedback
allows for significantly higher power and efficiency.
The ADuM5000 provides a regulation control output (RC
signal that can be connected to other isoPower devices. This feature
allows a single regulator to control multiple power modules without
contention. When auxiliary power modules are present, the V
pins can be connected together to work as a single supply. Because
there is only one feedback control path, the supplies work together
seamlessly. The ADuM5000 can be a source of regulation control,
as well as being controlled by another isoPower device.
There is an undervoltage lockout (UVLO) with hysteresis in the
V
the UVLO threshold, the dc-to-dc converter becomes active.
The input voltage must be decreased below the turn-on threshold
by the hysteresis value to disable the converter. This feature has
many benefits in the power-up sequence of the converter, such
as it ensures that the system supply rises to a minimum level
before the ADuM5000 demands current. It also prevents any
voltage drop due to converter current from turning the supply
off and possibly oscillating.
PCB LAYOUT
The ADuM5000 digital isolator is a 0.5 W isoPower integrated
dc-to-dc converter that requires no external interface circuitry
for the logic interfaces. Power supply bypassing is required at the
input and output supply pins (see Figure 14). The power supply
section of the ADuM5000 uses a 180 MHz oscillator frequency
to pass power efficiently through its chip-scale transformers. In
addition, the normal operation of the data section of the iCoupler
introduces switching transients on the power supply pins. Bypass
capacitors are required for several operating frequencies. Noise
suppression requires a low inductance, high frequency capacitor,
whereas ripple suppression and proper regulation require a
large value capacitor. These are most conveniently connected
between Pin 1 and Pin 2 for V
for V
of at least two capacitors is required. The recommended capacitor
values are 0.1 μF and 10 μF. Best practice recommends using a very
low inductance ceramic capacitor, or its equivalent, for the smaller
value. The total lead length between both ends of the capacitor and
the input power supply pin should not exceed 10 mm. Consider
bypassing between Pin 1 and Pin 8 and between Pin 9 and Pin 16
DD1
input protection circuit. When the input voltage rises above
ISO
. To suppress noise and reduce ripple, a parallel combination
DD1
and between Pin 15 and Pin 16
DD1
) side by a dedicated
DD1
power is supplied to
OUT
ISO
Rev. A | Page 11 of 16
)
ISO
)
unless both common ground pins are connected together close
to the package.
In applications involving high common-mode transients, ensure
that board coupling across the isolation barrier is minimized.
Furthermore, design the board layout such that any coupling
that does occur affects all pins equally on a given component side.
Failure to ensure this can cause voltage differentials between pins
exceeding the absolute maximum ratings for the device as specified
in Table 10, thereby leading to latch-up and/or permanent damage.
The ADuM5000 is a power device that dissipates approximately
1 W of power when fully loaded. Because it is not possible to apply
a heat sink to an isolation device, the device primarily depends
on heat dissipation into the PCB through the GND pins. If the
device is used at high ambient temperatures, provide a thermal
path from the GND pins to the PCB ground plane. The board
layout in Figure 14 shows enlarged pads for Pin 2 and Pin 8
(GND
vias from the pad to the ground plane to significantly reduce the
temperature inside the chip. The dimensions of the expanded pads
are at the discretion of the designer and depend on the available
board space.
STARTUP BEHAVIOR
The ADuM5000 does not contain a soft start circuit. Take the
startup current and voltage behavior into account when designing
with this device.
When power is applied to V
to operate and draw current when the UVLO minimum voltage
is reached. The switching circuit drives the maximum available
power to the output until it reaches the regulation voltage where
PWM control begins. The amount of current and time this
takes depends on the load and the V
Fast slew rates, in the 200 μs or smaller range, allow peak current
draws up to 100 mA/V of V
than the output can turn on; therefore, the peak current is
proportional to the maximum input voltage.
With a slow V
voltage does not change quickly when V
current surge is about 300 mA because V
the 2.7 V UVLO point. The behavior during startup is similar
to when the device load is a short circuit; these values are consistent
with the short-circuit current shown in Figure 7.
RC
RC
GND
GND
V
V
RC
1
OUT
DD1
DD1
) and for Pin 9 and Pin 15 (GND
SEL
IN
1
1
DD1
NC
Figure 14. Recommended PCB Layout
slew rate (in the millisecond range), the input
DD1
DD1
. The input voltage goes high faster
, the input switching circuit begins
DD1
ISO
DD1
DD1
slew rate.
). Implement multiple
NC
NC
reaches UVLO. The
is nearly constant at
NC
ADuM5000
V
GND
V
V
GND
ISO
SEL
ISO
ISO
ISO