8.1 Overview

ISO7831 employs an ON-OFF Keying (OOK) modulation scheme to transmit the digital data across a silicon dioxide based isolation barrier. The transmitter sends a high frequency carrier across the barrier to represent one digital state and sends no signal to represent the other digital state. The receiver demodulates the signal after advanced signal conditioning and produces the output through a buffer stage. If the EN pin is low then the output goes to high impedance. ISO7831 also incorporates advanced circuit techniques to maximize the CMTI performance and minimize the radiated emissions due the high frequency carrier and IO buffer switching. The conceptual block diagram of a digital capacitive isolator, Figure 11, shows a functional block diagram of a typical channel.

8.2 Functional Block Diagram

Figure 11. Conceptual Block Diagram of a Digital Capacitive Isolator

Also a conceptual detail of how the ON/OFF Keying scheme works is shown in Figure 12.

Figure 12. On-Off Keying (OOK) Based Modulation Scheme

8.3 Feature Description

8.3.1 High Voltage Feature Description

8.3.1.1 Package Insulation and Safety-Related Specifications

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	DW-16	8			mm
L(I02)(1)	Minimum external tracking (creepage)	Shortest terminal-to-terminal distance across the package surface	DW-16	8			mm
CTI	Tracking resistance (comparative tracking index)	DIN EN 60112 (VDE 0303-11); IEC 60112; UL 746A		600			V
RIO	Isolation resistance, input to output(2)	VIO = 500 V, TA = 25°C		1012			Ω
		VIO = 500 V, 100°C ≤ TA ≤ max		1011			Ω
CIO	Barrier capacitance, input to output(2)	VIO = 0.4 x sin (2πft), f = 1 MHz			2		pF
CI	Input capacitance(3)	VI = VCC/2 + 0.4 x sin (2πft), f = 1 MHz, VCC = 5 V			2		pF

(1) Per JEDEC package dimensions.

(2) All pins on each side of the barrier tied together creating a two-terminal device.

(3) 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

PARAMETER(1)		TEST CONDITIONS	SPECIFICATION	UNIT
DTI	Distance through the insulation	Minimum internal gap (internal clearance)	21	μm
VIOWM	Maximum isolation working voltage	Time dependent dielectric breakdown (TDDB) Test	1500	VRMS
			2121	VDC
DIN V VDE V 0884-10 (VDE V 0884-10):2006-12
VIOTM	Maximum transient isolation voltage	VTEST = VIOTM t = 60 sec (qualification) t= 1 sec (100% production)	8000	VPK
VIOSM	Maximum surge isolation voltage	Test method per IEC 60065, 1.2/50 µs waveform, VTEST = 1.6 x VIOSM = 12800 VPK (qualification)	8000	VPK
VIORM	Maximum repetitive peak isolation voltage		2121	VPK
VPR	Input-to-output test voltage	Method a, After Input/Output safety test subgroup 2/3, VPR = VIORM x 1.2, t = 10 s, Partial discharge < 5 pC	2545	VPK
		Method a, After environmental tests subgroup 1, VPR = VIORM x 1.6, t = 10 s, Partial Discharge < 5 pC	3394
		Method b1, VPR = VIORM x 1.875, t = 1 s (100% Production test) Partial discharge < 5 pC	3977
RS	Isolation resistance	VIO = 500 V at TS	>109	Ω
	Pollution degree		2
UL 1577
VISO	Withstanding isolation voltage	VTEST = VISO = 5700 VRMS, t = 60 sec (qualification), VTEST = 1.2 x VISO = 6840 VRMS, t = 1 sec (100% production)	5700	VRMS

(1) Climatic Classification 55/125/21

8.3.1.3 IEC 60664-1 Ratings Table

PARAMETER	TEST CONDITIONS	SPECIFICATION
Basic isolation group	Material group	I
Installation classification	Rated mains voltage ≤ 600 VRMS	I–IV
	Rated mains voltage ≤ 1000 VRMS	I–III

8.3.1.4 Regulatory Information

DW package certifications are complete.

VDE	CSA	UL	CQC
Certified according to DIN V VDE V 0884-10 (VDE V 0884-10):2006-12 and DIN EN 60950-1 (VDE 0805 Teil 1):2011-01	Approved under CSA Component Acceptance Notice 5A, IEC 60950-1, IEC 61010-1, and IEC 60601-1	Certified according to UL 1577 Component Recognition Program	Certified according to GB 4943.1-2011
Reinforced insulation Maximum transient isolation voltage, 8000 VPK; Maximum repetitive peak isolation voltage, 2121 VPK; Maximum surge isolation voltage, 8000 VPK	Reinforced insulation per CSA 61010-1-12 and IEC 61010-1 3rd Ed., 300 VRMS max working voltage;	Single protection, 5700 VRMS (1)	Reinforced Insulation, Altitude ≤ 5000 m, Tropical Climate, 250 VRMS maximum working voltage
	Reinforced insulation per CSA 60950-1-07+A1+A2 and IEC 60950-1 2nd Ed., 800 VRMS max working voltage (pollution degree 2, material group I) ;
	2 MOPP (Means of Patient Protection) per CSA 60601-1:14 and IEC 60601-1 Ed. 3.1, 250 VRMS (354 VPK) max working voltage
Certificate number: 40040142	Master contract number: 220991	File number: E181974	Certificate number: CQC15001121716

(1) Production tested ≥ 6840 V_RMS for 1 second in accordance with UL 1577.

8.3.1.5 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 for DW-16 Package	RθJA = 78.9°C/W, VI = 5.5 V, TJ = 150°C, TA = 25°C			288	mA
		RθJA = 78.9°C/W, VI = 3.6 V, TJ = 150°C, TA = 25°C			440
		RθJA = 78.9°C/W, VI = 2.75 V, TJ = 150°C, TA = 25°C			576
PS	Safety input, output, or total power	RθJA = 78.9°C/W, TJ = 150°C, TA = 25°C			1584	mW
TS	Maximum case temperature				150	°C

The maximum safety temperature is the maximum junction temperature specified for the device. 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 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. Thermal Derating Curve per VDE for
DW-16 Package

Figure 14. Thermal Derating Curve for Safety Limiting Power per VDE

8.4 Device Functional Modes

ISO7831 functional modes are shown in Table 1.

8.4.1 Device I/O Schematics

Figure 15. Device I/O Schematics