an1671

Application Note 1671
Author: Oscar Mansilla
ISL706xRH Evaluation Board User’s Guide
Introduction
Section 2
The ISL706xRHEVAL1Z evaluation board is a design platform
featuring all three versions of the rad hard 3.3V supervisory
circuits. It includes all the circuitry needed to characterize
critical performance parameters and enables evaluation of
basic functional operation and common application
implementations. Figures 1 and 2 illustrate the
ISL706xRHEVAL1Z in photographic and schematic forms,
respectively.
The middle position (Section 2), has the ISL706BRH installed
and is set-up as a 3.3V window detector. The VDD monitors for
UV and the PFI for OV via the R5, R6 divider. The PFO output is
inverted and connected to the manual reset input (MR) via U4.
Hence, a reset signal is generated when 3.06V < VDD > 3.45V.
If J4 is not installed, the PFO will be an OV indicator but no
reset signal will be generated. There is also a LED indicator for
an overvoltage condition, when VDD > 3.45V PFO is a high and
a LED will turn on indicating an OV condition. The active high
reset signal for the an UV condition maybe monitored through
the RST test point.
Section 3
FIGURE 1. ISL706xRHEVAL1Z
Evaluation Board Key Features
The ISL706xRHEVAL1Z is divided into three sections; each
section having one of the three available reset output versions.
The left position has the ISL706ARH and is set-up as a +5V
and +3.3V UV monitor with reset signal. The middle position
features the ISL706BRH set up as 3.3V window detector. The
right section contains the ISL706CRH in a bipolar voltage
sensing application.
Section 1
In the left position (Section 1), the ISL706ARH is configured to
monitor undervoltage conditions on a +3.3V supply through
the VDD pin and on a +5V supply through the PFI pin. The PFI
allows monitoring of any voltage above the 0.6V PFI reference
and with a resistor divider is used to monitor the +5V. The
rising threshold for the +5V auxiliary voltage is set to 3V via the
R1, R2 divider, when this condition is met PFO will be high
driving on a green LED. When the +5V auxiliary voltage falls
below 3V, PFO is pulled low and a red LED will be turned on.
There is an option to add hysteresis to the power fail
comparator by adding a resistor on pad R13. The active low
reset signal maybe monitored through the RST test point.
There is also a MR test point in order to drive the MR low to
test its functionality.
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The right position (Section 3), features the ISL706CRH in a
negative voltage sensing application. A +3.3V supply is
monitored through the VDD pin and a -5V supply is monitored
on the PFI pin with use of the R7, R8 resistor divider network.
Both pins are sensing for an under voltage condition. When the
-5V supply rail drops below -4.5V, PFO will be high driving on
the N3904 NPN transistor. As the NPN turns on, the manual
reset (MR) pin will be pull low initiating a reset. An UV condition
on the +3.3V supply may be monitored on the RST_OD pin,
which has a 3.01kΩ pull-up resistor to VDD.
Watchdog Timer Functionality
All of these positions have independent Watchdog input (WDI)
and Watchdog output (WDO) test points to evaluate the
functionality the watchdog timer. A waveform generator may
be used to apply a square wave signal to the WDI test points
and the output monitored through the WDO test points. The
WDI may also be left open and WDO is now a low line indicator
of the voltage on VDD.
Power Supplies
External power connections are made through the VDD, 5V, -5V and
GND connections on the evaluation board. All three sections share
a common VDD test point with a decoupling capacitor C1, C2 and
C3 placed close to each IC. The PFI pins in sections 1 and 2 have
a unpopulated component pad to add decoupling capacitors
C2 and C3 if needed.
Reference Documents
ISL705xRH Data Sheet, FN7662
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Copyright Intersil Americas Inc. 2011. All Rights Reserved.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
Application Note 1671
RST OD
SECTION 1 - ISL706ARH
SECTION 2 - ISL706BRH
SECTION 3 - ISL706CRH
FIGURE 2. ISL706xRHEVAL1Z SIMPLIFIED SCHEMATIC
Bill of Materials
TABLE 1. ISL706XRHEVAL1Z COMPONENTS PARTS LIST
DEVICE #
DESCRIPTION
COMMENTS
C1, C3, C5
CAP, SMD, 0603, 0.1µF, 50V, 10%, X7R, ROHS
Power Supply Decoupling
C2, C4
CAP, SMD, 0603, DNP, ROHS
User selectable capacitors - not populated
D1, D2, D3
LED, SMD, ROHS
Power Fail Indicator
Q1, Q3
N-Channel EMF Effect Transistor, SMD, SOT-23,ROHS
Power Fail Detector
Q2
P-Channel EMF Effect Transistor, SMD, SOT-23,ROHS
Power Fail Detector
Q4
NPN General Purpose Transistor, SMD, SOT-223, ROHS
R1
RES, SMD, 0603, 383kΩ, 1/16W, 1%, ROHS
PFI Voltage Divider Network
R2, R6
RES, SMD, 0603, 49.9kΩ, 1/10W, 1%, ROHS
PFI Voltage Divider Network
R3, R4, R12
RES, SMD, 0603, 1kΩ, 1/10W, 1%, ROHS
LED Current Limiting Resistor
R5
RES, SMD, 0603, 165kΩ, 1/16W, 1%, ROHS
PFI Voltage Divider Network
R7, R9, R10
RES, SMD, 0603, 100kΩ, 1/16W, 1%, ROHS
PFI Voltage Divider Network
R11
RES, SMD, 0603, 5.1kΩ, 1/16W, 1%, ROHS
ISL705CRH Reset Pull-up Resistor
R13
RES, SMD, 0603, DNP
Placeholder for Addition of Hysteresis
U1
ISL706ARH, 8 Ld Flatpack, 3.3V Supervisory Circuit
Supervisory Circuit with Active Low RESET
U2
ISL706BRH, 8 Ld Flatpack, 3.3V Supervisory Circuit
Supervisory Circuit with Active High RESET
U3
ISL706CRH, 8 Ld Flatpack, 3.3V Supervisory Circuit
Supervisory Circuit with Open Drain RESET
U4
UHS Inverter with Schmitt Trigger Input, SC70, ROHS
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Application Note 1671
ISL706xEVAL1Z Board Layout
FIGURE 3. ISL706xEVAL1Z TOP VIEW
FIGURE 4. ISL706xEVAL1Z TOP LAYER
Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is
cautioned to verify that the Application Note or Technical Brief is current before proceeding.
For information regarding Intersil Corporation and its products, see www.intersil.com
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