ADUM3190 查看數據表（PDF） - Analog Devices

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ADUM3190

High Stability Isolated Error Amplifier

Analog Devices 

ADuM3190

Data Sheet

ISOLATED DC-TO-DC SUPPLY

VOUT

R1

–IN

VIN = 0.35V TO 1.5V +IN

R2

ERROR

AMP

VREF

1.225V

REFOUT

ADuM3190

Figure 25. Setting the Output Voltage

DOSA MODULE APPLICATION

Figure 26 is a block diagram of a Distributed-power Open

Standards Alliance (DOSA) circuit using the ADuM3190. The

block diagram shows how to use the ADuM3190 1.225 V refer-

ence and the error amp in a DOSA standard power supply module

circuit to produce output voltage settings using a combination

of resistors.

The ADuM3190 1.225 V reference is specified for ±1% over the

−40°C to +125°C temperature range. See Table 10 to select the

resistor values to set the output voltage of the module. Two

different ranges of VOUT can be implemented, VOUT > 1.5 V or

VOUT < 1.5 V, depending on the required module.

DOSA MODULE

VOUT

R1

VIN = 0.35V TO 1.5V

ERROR

AMP

R2

R3

VREF

ADuM3190 1.225V

R5 R4

R6

RTRIM-UP

OPTIONAL TRIM-UP

OR TRIM-DOWN

RESISTOR OR ±10%

OF NOMINAL VALUE

ACCORDING TO DOSA

RTRIM-DOWN

a default high impedance state by the watchdog timer circuit. In

addition, the outputs are in a default high impedance state while

the power is increasing before the UVLO threshold is crossed.

The ADuM3190 is immune to external magnetic fields. The limi-

tation on the ADuM3190 magnetic field immunity is set by the

condition whereby induced voltage in the transformer receiving

coil is sufficiently large to either falsely set or reset the decoder.

The following analysis defines the conditions under which this

can occur. The 3 V operating condition of the ADuM3190 is

examined because it represents the most susceptible mode of

operation. The pulses at the transformer output have an amplitude

that is greater than 1.0 V. The decoder has a sensing threshold at

approximately 0.5 V, therefore establishing a 0.5 V margin within

which induced voltages are tolerated. The voltage induced across

the receiving coil is given by

V = (−dβ/dt) ∑π rn2, n = 1, 2, … , N

where:

β is the magnetic flux density (gauss).

rn is the radius of the nth turn in the receiving coil (cm).

N is the number of turns in the receiving coil.

Given the geometry of the receiving coil in the ADuM3190 and

an imposed requirement that the induced voltage be, at most,

50% of the 0.5 V margin at the decoder, a maximum allowable

magnetic field is calculated, as shown in Figure 27.

100

10

1

0.1

Figure 26. DOSA Module

Table 10. Resistor Values for DOSA Module

Module

Nominal Output

R3

R4

R5

VOUT > 1.5 V

1 kΩ 1 kΩ 0 Ω

R6

Open

0.01

0.001

1k

10k

100k

1M

10M

100M

VOUT < 1.5 V

1 kΩ 0 Ω

2.05 kΩ 1.96 kΩ

MAGNETIC FIELD FREQUENCY (Hz)

VOUT > 1.5 V

5.11 kΩ 5.11 kΩ 0 Ω

Open

Figure 27. Maximum Allowable External Magnetic Flux Density

VOUT < 1.5 V

5.11 kΩ 0 Ω

10.5 kΩ 10.0 kΩ

For example, at a magnetic field frequency of 1 MHz, the maxi-

DC CORRECTNESS AND MAGNETIC FIELD IMMUNITY

mum allowable magnetic field of 0.02 kgauss induces a voltage

of 0.25 V at the receiving coil. This is approximately 50% of the

Positive and negative logic transitions at the isolator input cause

narrow (~1 ns) pulses to be sent to the decoder via the transformer.

The decoder is bistable and is, therefore, either set or reset by

the pulses, indicating input logic transitions. In the absence of

logic transitions of more than 1 µs at the input, a periodic set of

sensing threshold and does not cause a faulty output transition.

Similarly, if such an event were to occur during a transmitted

pulse (and had the worst-case polarity), the received pulse is

reduced from >1.0 V to 0.75 V, still well above the 0.5 V sensing

threshold of the decoder.

refresh pulses indicative of the correct input state are sent to

ensure dc correctness at the output.

The preceding magnetic flux density values correspond to

specific current magnitudes at given distances away from the

If the decoder receives no internal pulses for more than approx-

imately 3 µs, the input side is assumed to be unpowered or

nonfunctional, in which case, the isolator output is forced to

ADuM3190 transformers. Figure 28 shows these allowable

current magnitudes as a function of frequency for selected dis-

tances. As shown Figure 28, the ADuM3190 is immune and can

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