A6850KLTR-T Allegro Microsystems Inc, A6850KLTR-T Datasheet - Page 5

• Manufacturer Part Number: A6850KLTR-T
• Description: IC SWITCH INTERFACE 2CHAN 8-SOIC
• Manufacturer: Allegro Microsystems Inc
• Type: Hall Effect Switchr

Specifications of A6850KLTR-T

• Input Type: Voltage
• Output Type: Voltage
• Interface: 2-Wire Serial
• Current - Supply: 5mA
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Interface Applications: Microprocessors, 2 Wire Hall Effect Sensor IC
• Supply Voltage Range: 4.75V To 26.5V
• Power Dissipation Pd: 52mW
• Operating Temperature Range: -40°C To +125°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 620-1185-2

A6850
SENSE Pin Outputs
The A6850 divides the OUTPUTx pin current by 10 and mirrors
it onto the corresponding SENSEx pin. Putting sense resistors,
RSENSE , from these pins to ground will create a voltage that
can be read by an ADC (analog-to-digital converter). The value
of R
sense resistor (V
rating of the ADC. For further protection of the ADC, an external
clamping circuit, such as a Zener diode, can be used to clamp any
transient current spikes that may occur on the output that would
be translated onto the SENSE pins.
The sense current is one tenth of the output current, plus an offset
current. This offset current is consistent across the whole range
of the output current. The sense current can be calculated by the
following formula:
The sense resistor must also be chosen to meet the voltage limits
on the sense pin (see Electrical Characteristics table).
Output Current Limit
The A6850 limits the output current to a maximum current of
I
until the output load is reduced or the A6850 goes into thermal
shutdown.
The high output current limit allows the bypass capacitor, C
on the Hall sensor IC to charge up quickly. This allows a high slew
rate on the VCC pin of the Hall sensor IC, ensuring that the sensor
IC Power-On State will be correct. See the Applications Informa-
tion section for schematic diagrams and power calculations.
Output Faults
The A6850 withstands short-to-ground or short-to-battery of the
OUTPUTx pins. In the case of short-to-ground, current is held to
the current limit (I
If V
A6850 monitors V
protection circuitry requires a finite amount of time to disable the
outputs, a bypass capacitor of 1 μF is necessary on V
OUTPUTx sinks current into the A6850 in this state, the reverse
current is shunted to ground and does not appear on the VIN pin.
OUTPUTM
OUTPUTx
SENSE
I
SENSEx
. The output current will remain at the current limit
should be chosen so that the voltage drop across the
> (V
= (I
RSENSE
IN
OUTPUTM
OUTPUTx
OUTPUTx
+ 0.7 V) during a short-to-battery event, the
) does not exceed the maximum voltage
).
and disables the outputs. Because the
/ 10) + I
SENSE(ofs)
.
Functional Description
IN
. Although
BYP
(1)
,
Dual Channel Switch Interface IC
Figure 3. Activation Timing Diagram. Exiting Sleep mode via ENABLE
signal to output waveform.
Overvoltage Protection
The A6850 has built-in overvoltage protection against a load
dump on the supply bus. In the case of a load dump, or when V
is connected to the battery supply bus and V
overvoltage threshold, V
Sleep Mode
Low-leakage or sleep modes are required in automotive applica-
tions to minimize battery drain when the vehicle is parked. The
A6850 enters sleep mode when both ENABLE pins are low. In
sleep mode, the internal regulators and all other internal circuitry
are disabled.
When enabling an output, the part must first come out of sleep
mode. Consequently, the wake-up time amounts to a propagation
delay before the outputs turn on. Also, the ENABLE pins do not
switch with hysteresis until the regulators stabilize.
After the internal regulators stabilize, internal circuitry is enabled
and the outputs turn on, as shown in figure 3. As long as one
ENABLE pin is held high, the A6850 operates with hysteresis.
OUTPUT
ENABLE
V
REG
V
ENABLEL
OVP
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
> t
, the A6850 will shut off the outputs.
RegOk
ON
IN
rises above the
IN
5