SLLSED3C June   2013  – July 2015 ISO7420FCC

UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics: VCC1 and VCC2 = 5 V ± 10%
    6. 6.6  Electrical Characteristics: VCC1 and VCC2 = 3.3 V ± 10%
    7. 6.7  Electrical Characteristics: VCC1 and VCC2 = 2.7 V
    8. 6.8  Power Dissipation Characteristics
    9. 6.9  Switching Characteristics: VCC1 and VCC2 = 5 V ± 10%
    10. 6.10 Switching Characteristics: VCC1 and VCC2 = 3.3 V ± 10%
    11. 6.11 Switching Characteristics: VCC1 and VCC2 = 2.7 V
    12. 6.12 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Insulation and Safety-Related Specifications for SOIC-8 Package
      2. 8.3.2 Insulation Characteristics
      3. 8.3.3 Regulatory Information
      4. 8.3.4 Safety Limiting Values
    4. 8.4 Device Functional Modes
      1. 8.4.1 Device I/O Schematics
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Supply Current Equations
          1. 9.2.2.1.1 Maximum Supply Current Equations
          2. 9.2.2.1.2 Typical Supply Current Equations
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 PCB Material
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8 Detailed Description

8.1 Overview

The isolator in Figure 15 is based on a capacitive isolation barrier technique. The I/O channel of the device consists of two internal data channels, a high-frequency channel (HF) with a bandwidth from 100 kbps up to
50 Mbps, and a low-frequency channel (LF) covering the range from 100 kbps down to DC. In principle, a single- ended input signal entering the HF-channel is split into a differential signal via the inverter gate at the input. The following capacitor-resistor networks differentiate the signal into transients, which then are converted into differential pulses by two comparators. The comparator outputs drive a NOR-gate flip-flop whose output feeds an output multiplexer. A decision logic (DCL) at the driving output of the flip-flop measures the durations between signal transients. If the duration between two consecutive transients exceeds a certain time limit, (as in the case of a low-frequency signal), the DCL forces the output-multiplexer to switch from the high- to the low-frequency channel.

Because low-frequency input signals require the internal capacitors to assume prohibitively large values, these signals are pulse-width modulated (PWM) with the carrier frequency of an internal oscillator, thus creating a sufficiently high frequency signal, capable of passing the capacitive barrier. As the input is modulated, a low-pass filter (LPF) is needed to remove the high-frequency carrier from the actual data before passing it on to the output multiplexer.

8.2 Functional Block Diagram

ISO7420FCC fbdc_sllsed3.gifFigure 15. Conceptual Block Diagram of a Digital Capacitive Isolator

8.3 Feature Description

8.3.1 Insulation and Safety-Related Specifications for SOIC-8 Package

over recommended operating conditions (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
L(I01) Minimum air gap (clearance) Shortest terminal-to-terminal distance through air 4 mm
L(I02) Minimum external tracking (creepage) Shortest terminal-to-terminal distance across the package surface 4 mm
CTI Tracking resistance (comparative tracking index) DIN EN 60112 (VDE 0303-11); IEC 60112 >400 V
DTI Distance through the insulation Minimum internal gap (internal clearance) 0.014 mm
RIO Isolation resistance, input to output(1) VIO = 500 V, TA = 25°C >1012 Ω
VIO = 500 V, 100°C ≤ TA ≤ 125°C >1011 Ω
CIO Barrier capacitance, input to output(1) VIO = 0.4 sin (2πft), f = 1 MHz 1 pF
CI Input capacitance(2) VI = VCC/2 + 0.4 sin (2πft), f = 1 MHz, VCC = 5 V 1 pF
(1) All pins on each side of the barrier tied together creating a two-terminal device.
(2) Measured from input pin to ground.

NOTE

Creepage and clearance requirements should be applied according to the specific equipment isolation standards of an application. Care should be taken to maintain the creepage and clearance distance of a board design to ensure that the mounting pads of the isolator on the printed-circuit board do not reduce this distance.

Creepage and clearance on a printed-circuit board become equal in certain cases. Techniques such as inserting grooves and/or ribs on a printed circuit board are used to help increase these specifications.

8.3.2 Insulation Characteristics

over recommended operating conditions (unless otherwise noted)
PARAMETER TEST CONDITIONS SPECIFICATION UNIT
DIN V VDE V 0884-10 (VDE V 0884-10):2006-12(1)
VIORM Maximum working isolation voltage 566 VPK
VPR Input-to-output test voltage Method a, After environmental tests subgroup 1,
VPR = VIORM x 1.6, t = 10 s,
Partial Discharge < 5 pC		 906 VPK
Method b1,
VPR = VIORM x 1.875, t = 1 s (100% Production test)
Partial discharge < 5 pC		 1062
After Input/Output safety test subgroup 2/3,
VPR = VIORM x 1.2, t = 10 s,
Partial discharge < 5 pC		 680
VIOTM Maximum transient isolation voltage VTEST = VIOTM
t = 60 sec (qualification)
t= 1 sec (100% production)		 4242 VPK
RS Isolation resistance VIO = 500 V at TS = 150°C >109 Ω
Pollution degree 2
UL 1577
VISO Isolation voltage VTEST = VISO = 2500 VRMS, t = 60 sec (qualification)
VTEST = 1.2 x VISO= 3000 VRMS, t = 1 sec (100% production)		 2500 VRMS
(1) Climatic Classification 40/125/21

Table 1. IEC 60664-1 Ratings Table

PARAMETER TEST CONDITIONS SPECIFICATION
Material group II
Installation classification Rated mains voltage ≤ 150 VRMS I–IV
Rated mains voltage ≤ 300 VRMS I–III

8.3.3 Regulatory Information

VDE CSA UL CQC
Certified according to DIN V VDE V 0884-10 (VDE V 0884-10):2006-12 and DIN EN 61010-1 (VDE 0411-1):2011-07 Approved under CSA Component Acceptance Notice 5A, IEC 60950-1, and IEC 61010-1 Recognized under UL 1577 Component Recognition Program Certified according to GB4943.1-2011
Basic Insulation
Maximum Transient Isolation voltage, 4242 VPK;
Maximum Working Isolation Voltage, 566 VPK		 3000 VRMS Isolation Rating;
400 VRMS Basic and 200 VRMS Reinforced Insulation maximum working voltage per CSA 60950-1-07+A1 and IEC 60950-1 (2nd Ed)+A1;
300 VRMS Basic and 150 VRMS Reinforced Insulation maximum working voltage per CSA 61010-1-12 and IEC 61010-1 (3rd Ed)

Single Protection, 2500 VRMS(1) Basic Insulation, Altitude ≤ 5000m, Tropical Climate, 250 VRMS maximum working voltage
Certificate number: 40016131 Master contract number: 220991 File number: E181974 Certificate number: CQC14001109540
(1) Production tested ≥ 3000 VRMS for 1 second in accordance with UL 1577.

8.3.4 Safety Limiting Values

Safety limiting intends to prevent potential damage to the isolation barrier upon failure of input or output circuitry. A failure of the I/O can allow low resistance to ground or the supply and, without current limiting, dissipate sufficient power to overheat the die and damage the isolation barrier, potentially leading to secondary system failures.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
IS Safety input, output, or supply current θJA = 115.1°C/W, VI = 5.5 V, TJ = 150°C, TA = 25°C 197 mA
θJA = 115.1°C/W, VI = 3.6 V, TJ = 150°C, TA = 25°C 302
θJA = 115.1°C/W, VI = 2.7 V, TJ = 150°C, TA = 25°C 402
TS Maximum Safety temperature 150 °C

The safety-limiting constraint is the absolute-maximum junction temperature specified in the Absolute Maximum Ratings table. The power dissipation and junction-to-air thermal impedance of the device installed in the application hardware determines the junction temperature. The assumed junction-to-air thermal resistance in the Thermal Information table is that of a device installed on a High-K Test Board for Leaded Surface-Mount Packages. The power is the recommended maximum input voltage times the current. The junction temperature is then the ambient temperature plus the power times the junction-to-air thermal resistance.

ISO7420FCC C000_SLLSED3.pngFigure 16. θJC Thermal Derating Curve per VDE

8.4 Device Functional Modes

Table 2. Function Table(1)

VCC1 VCC2 INPUT
INA, INB		 OUTPUT
OUTA, OUTB
PU PU H H
L L
Open L(2)
PD PU X L(2)
X PD X Undetermined
(1) PU = Powered up (VCC ≥ 2.7 V); PD = Powered down (VCC ≤ 2.1 V); X = Irrelevant; H = High level; L = Low level
(2) In fail-safe condition, output defaults to low level

8.4.1 Device I/O Schematics

ISO7420FCC Device_IO_SLLSED3.gifFigure 17. Device I/O Schematics