8.1 Overview

The isolator in Figure 12 is based on a capacitive isolation barrier technique. The I/O channel of the device consists of two internal data channels, a high-frequency (HF) channel with a bandwidth from 100 kbps up to 25 Mbps, and a low-frequency (LF) channel 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 transient pulses, which then are converted into CMOS levels by a comparator. The transient pulses at the input of the comparator can be either above or below the common mode voltage VREF depending on whether the input bit transitioned from 0 to 1 or 1 to 0. The comparator threshold is adjusted based on the expected bit transition. A decision logic (DCL) at the output of the HF channel comparator 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-frequency to the low-frequency channel.

8.2 Functional Block Diagram

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, 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.

8.3 Feature Description

8.3.1 High Voltage Feature Description

8.3.1.1 Insulation and Safety-Related Specifications for D-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	Minimum internal gap (internal clearance)	Distance through the insulation		13			µm
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	Isolation capacitance, input to output(1)	VIO = 0.4 sin (2πft), f = 1 MHz			0.5		pF
CI	Input capacitance(2)	VI = VCC/2 + 0.4 sin (2πft), f = 1 MHz, VCC = 5 V			1.6		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.

8.3.1.2 Insulation Characteristics

over recommended operating conditions (unless otherwise noted)

PARAMETER(1)		TEST CONDITIONS	SPECIFICATION	UNIT
VIOWM	Maximum isolation working voltage		400	VRMS
VIORM	Maximum repetitive peak voltage per DIN V VDE V 0884-10		566	VPK
VPR	Input-to-output test voltage per DIN V VDE V 0884-10	After Input/Output safety test subgroup 2/3, VPR = VIORM x 1.2, t = 10 s, Partial discharge < 5 pC	680	VPK
		Method a, After environmental tests subgroup 1, VPR = VIORM x 1.6, t = 10 s, Partial Discharge < 5 pC	906
		Method b1, VPR = VIORM x 1.875, t = 1 s (100% Production test) Partial discharge < 5 pC	1062
VIOTM	Maximum transient overvoltage per DIN V VDE V 0884-10	VTEST = VIOTM t = 60 sec (qualification) t= 1 sec (100% production)	4242	VPK
VIOSM	Maximum surge isolation voltage per DIN V VDE V 0884-10	Test method per IEC 60065, 1.2/50 µs waveform, VTEST = 1.3 x VIOSM = 7800 VPK (qualification)	6000	VPK
VISO	Withstand isolation voltage per UL 1577	VTEST = VISO = 3000 VRMS, t = 60 sec (qualification); VTEST = 1.2 x VISO = 3600 VRMS, t = 1 sec (100% production)	3000	VRMS
RS	Insulation resistance	VIO = 500 V at TS = 150°C	>109	Ω
	Pollution degree		2

(1) Climatic Classification 40/125/21

Table 1. IEC 60664-1 Ratings Table

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

8.3.1.3 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 Overvoltage, 4242 VPK; Maximum Surge Isolation Voltage, 6000 VPK; Maximum Repetitive Peak Voltage, 566 VPK	400 VRMS Basic Insulation and 200 VRMS Reinforced Insulation working voltage per CSA 60950-1-07+A1+A2 and IEC 60950-1 2nd Ed.+A1+A2; 300 VRMS Basic Insulation working voltage per CSA 61010-1-12 and IEC 61010-1 3rd Ed.	Single protection, 3000 VRMS(1)	Basic Insulation, Altitude ≤ 5000 m, Tropical Climate, 250 VRMS maximum working voltage
Certificate number: 40016131	Master contract number: 220991	File number: E181974	Certificate number: CQC15001121656

(1) Production tested ≥ 3600 V_RMS for 1 second in accordance with UL 1577.

8.3.1.4 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	RθJA = 119.9 °C/W, VI = 5.5 V, TJ = 150°C, TA = 25°C			190	mA
		RθJA = 119.9 °C/W, VI = 3.6 V, TJ = 150°C, TA = 25°C			290
TS	Maximum case temperature				150	°C

The safety-limiting constraint is the absolute-maximum junction temperature specified in the Absolut Maximun 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.

Figure 13. θ_JC Thermal Derating Curve per DIN V VDE 0884-10

8.4 Device Functional Modes

8.4.1 Device I/O Schematics

Figure 14. Device I/O Schematics