EVAL-ADUM4135EBZ Datasheet, PDF (3/6 Pages) Analog Devices – Desaturation protection circuitry

EVAL-ADuM4135EBZ User Guide
UG-854
SETTING UP THE EVAL-ADUM4135EBZ
INITIAL CONFIGURATION
PAD LAYOUT FOR THE DEVICE UNDER TEST (DUT)
Before the first use, certain things must be completed to prepare
the board for operation. In the stock configuration, the R1 to R6
resistors are not placed. These are the locations of the series
external resistors for the charging and discharging paths to
VOUT_ON and VOUT_OFF. It is recommended to use 1206 surface-
mount resistors with values between approximately 1 Ω and
10 Ω, depending on the load being driven. An actual IGBT or
MOSFET can be placed in the provided landing patterns to the
right of P1 and P2. P1 and P2 allow shorting across the series
external resistors to observe overshoot and/or allow the user to
probe voltage to quantify peak currents.
Figure 4 shows the top layer artwork for the dual gate driver circuit.
• U1 is the footprint for the ADuM4135.
• C1, C2, and C4 are 0.1 µF bypass capacitors; C3 and C5 are
10 µF bypass capacitors.
• The available footprint can be populated with TO-252
MOSFETs or IGBTs with the pinout shown in Figure 2.
• R1 to R6 are gate resistors that control the edges of the
outputs. By default, no resistors are installed; these resistors
must be populated with low value 1206 resistors, generally
in the 1 Ω to 10 Ω range.
In the stock configuration, the DESAT circuitry is left open.
Before the first use, if DESAT functionality is not used, it is
recommended to short the DESAT pin to ground, either by a
wire or by placing a 0 Ω resistor in the C6 component pad.
2
C/D
Failure to do so results in a DESAT fault being observed on the
first rising edge of the output.
If the DESAT circuitry is tested, an IGBT or MOSFET must be
added to the circuit to allow for the DESAT pin to be pulled
down during on times, preventing the DESAT fault. Additionally,
C6, R12, and D1 must have appropriate components placed. For
details about sizing, refer to the ADuM4135 data sheet. R11 is
provided to allow extra DESAT blanking current by means of
an external pull-up resistor. C7 can provide decoupling for this
external pull-up current source, if desired.
R13 and R14 come with 10 kΩ resistors in place. These resistors
provide pull ups to the READY and nFault pins. P3 allows for
easy enabling and disabling of the device by means of jumper
pins. A silkscreen reminder is included to show which pins to
short to enable or disable the device. R8 and R10 allow for easy
placement of 50 Ω terminating resistors, if desired.
Pins accompany the screw terminals. It is left to the user to
decide which connection mechanism to use. Do not leave VSS2
floating. It must always be at or less than the potential of GND2.
Shorting VSS2 and GND2 is a valid operating point.
During operation, if a fault is seen, the nFault pin is brought
low. In this case, the device can be reset by either powering
down VDD1 to VSS1 and powering back up, or by bringing the
nRESET pin low then high again. The easiest way to toggle
nRESET is to remove the jumper on P3 from Pin 2 and Pin 3
and then replace it. An internal pull-down resistor brings
nRESET low on its own.
1
3
G
E/S
Figure 2. IGBT/MOSFET Footprint
POWER CONNECTIONS
Follow these steps to connect the EVAL-ADuM4135EBZ
evaluation board to the power supply:
1. Connect the 5 V or 3.3 V input supply with the positive
terminal on VDD1 and the ground on VSS1.
2. Connect the ADuM4135 VDD2 supply voltage (12 V to
30 V) to the VDD2 pin and its return to the VSS2 pin.
VSS1 and VSS2 are functionally isolated. The emitter/source of
the IGBT/MOSFET is tied to GND2.
INPUT/OUTPUT CONNECTIONS
The VI+ and VI− pins are CMOS inputs. R8 and R10 are provided
in case the user needs to terminate the inputs with a 50 Ω load.
R7 and R9 are provided as a place to put damping, if needed;
however, in most cases, the 0 Ω resistors that comes in the stock
configuration can remain on R7 and R9.
The EVAL-ADuM4135EBZ evaluation board comes with screw
terminals for both the input and output connections. These are
to facilitate connection options but are not the best option for
high performance transient testing. The best measurements
performed on the load, whether it is an IGBT or MOSFET or a
load capacitor, come from small loop measurements performed
right at the load. Using the screw terminals as either the sensing
node or for the connection of the load often results in overshoot
being observed during measurement.
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