AD8210YRZ Datasheet AD8210YRZ-REEL7, AD8210YRZ, AD8210WYRZ | P13-P15

AD8210 Data Sheet

Rev. D | Page 12 of 16

External Referenced Output

Tying both V

REF

pins together to an external reference produces

an output offset at the reference voltage when there is no

differential input (see Figure 29). When the input is negative

relative to the −IN pin, the output moves down from the

reference voltage. When the input is positive relative to the

−IN pin, the output increases.

AD8210

OUTPUT

G = +20

+IN –IN

REF

GND

REF

05147-007

0.1µF

0V ≤ V

REF

≤ V

Figure 29. External Reference Output

Splitting an External Reference

In this case, an external reference is divided by two with

an accuracy of approximately 0.2% by connecting one

REF

pin to ground and the other V

REF

pin to the reference

voltage (see Figure 30).

Note that Pin V

REF

1 and Pin V

REF

2 are tied to internal precision

resistors that connect to an internal offset node. There is no

operational difference between the pins.

For proper operation, the AD8210 output offset should not be

set with a resistor voltage divider. Any additional external

resistance could create a gain error. A low impedance voltage

source should be used to set the output offset of the AD8210.

AD821

G = +20

+IN

–I

REF

05147-008

µF

REF

0V ≤ V

≤ V

Figure 30. Split External Reference

Splitting the Supply

By tying one reference pin to V+ and the other to the GND pin,

the output is set at midsupply when there is no differential input

(see Figure 31). This mode is beneficial because no external

reference is required to offset the output for bidirectional

current measurement. This creates a midscale offset that is

ratiometric to the supply, meaning that if the supply increases

or decreases, the output still remains at half scale. For example,

if the supply is 5.0 V, the output is at half scale or 2.5 V. If the

supply increases by 10% (to 5.5 V), the output also increases by

10% (2.75 V).

0.1µF

AD8210

OUTPUT

G = +20

+IN –IN

REF

GND

05147-009

Figure 31. Split Supply

Data Sheet AD8210

Rev. D | Page 13 of 16

INPUT FILTERING

In typical applications, such as motor and solenoid current

sensing, filtering at the input of the AD8210 can be beneficial

in reducing differential noise, as well as transients and current

ripples flowing through the input shunt resistor. An input low-

pass filter can be implemented as shown in Figure 32.

The 3 dB frequency for this filter can be calculated by

FILTER

×××

2π

dB3_

(1)

Adding outside components, such as R

FILTER

and C

FILTER

introduces additional errors to the system. To minimize these

errors as much as possible, it is recommended that R

FILTER

10 Ω or lower. By adding the R

FILTER

in series with the 2 kΩ

internal input resistors of the AD8210, a gain error is

introduced. This can be calculated by













−

×−=

FILTER

ErrorGain

kΩ2

100100(%)

(2)

AD8210

OUTPUT

G = +20

SHUNT

< R

FILTER

≤ 10Ω R

FILTER

≤ 10Ω

+IN –IN

REF

GND

REF

05147-013

0.1µF

0V ≤ V

REF

≤ V

Figure 32. Input Low-Pass Filtering

AD8210 Data Sheet

Rev. D | Page 14 of 16

APPLICATIONS INFORMATION

The AD8210 is ideal for high-side or low-side current sensing.

Its accuracy and performance benefits applications, such as

3-phase and H-bridge motor control, solenoid control, and

power supply current monitoring.

For solenoid control, two typical circuit configurations are used:

high-side current sense with a low-side switch, and high-side

current sense with a high-side switch.

HIGH-SIDE CURRENT SENSE WITH A LOW-SIDE

SWITCH

In this case, the PWM control switch is ground referenced. An

inductive load (solenoid) is tied to a power supply. A resistive

shunt is placed between the switch and the load (see Figure 33).

An advantage of placing the shunt on the high side is that the

entire current, including the recirculation current, can be meas-

ured because the shunt remains in the loop when the switch is

off. In addition, diagnostics can be enhanced because short circuits

to ground can be detected with the shunt on the high side.

05147-010

INDUCTIVE

LOAD

AMP

DIODE

BATTERY

SHUNT

SWITCH

NC = N

O CONNECT

+IN V

REF

1 +V

OUT

–

IN GND V

REF

2 NC

AD8210

0.1µF

Figure 33. Low-Side Switch

In this circuit configuration, when the switch is closed, the

common-mode voltage moves down to the negative rail. When

the switch is opened, the voltage reversal across the inductive

load causes the common-mode voltage to be held one diode

drop above the battery by the clamp diode.

HIGH-SIDE CURRENT SENSE WITH A HIGH-SIDE

SWITCH

This configuration minimizes the possibility of unexpected

solenoid activation and excessive corrosion (see Figure 34). In

this case, both the switch and the shunt are on the high side.

When the switch is off, the battery is removed from the load,

which prevents damage from potential short circuits to ground,

while still allowing the recirculation current to be measured and

diagnostics to be preformed. Removing the power supply from

the load for the majority of the time minimizes the corrosive

effects that could be caused by the differential voltage between

the load and ground.

05147-011

INDUCTIVE

LOAD

CLAMP

DIODE

BATTERY

SHUNT

SWITCH

NC = NO CONNECT

+IN

REF

OUT

–IN

GND

REF

AD8210

0.1µF

Figure 34. High-Side Switch

Using a high-side switch connects the battery voltage to the

load when the switch is closed. This causes the common-mode

voltage to increase to the battery voltage. In this case, when the

switch is opened, the voltage reversal across the inductive load

causes the common-mode voltage to be held one diode drop

below ground by the clamp diode.

H-BRIDGE MOTOR CONTROL

Another typical application for the AD8210 is as part of the

control loop in H-bridge motor control. In this case, the AD8210

is placed in the middle of the H-bridge (see Figure 35) so that it

can accurately measure current in both directions by using the

shunt available at the motor. This configuration is beneficial for

measuring the recirculation current to further enhance the

control loop diagnostics.

05147-012

SHUNT

2.5V

CONTROLLER

NC = NO CONNECT

MOTOR

+IN V

REF

1 +V

OUT

–IN

GND

REF

2 NC

AD8210

0.1µF

Figure 35. Motor Control Application

The AD8210 measures current in both directions as the H-bridge

switches and the motor changes direction. The output of the

AD8210 is configured in an external reference bidirectional

mode (see the Modes of Operation section).

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P17

AD8210YRZ

Mfr. #:

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Description:

Current Sense Amplifiers High Voltage Bidirectional

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