A4940KLPTR-T Allegro Microsystems Inc, A4940KLPTR-T Datasheet - Page 8

• Manufacturer Part Number: A4940KLPTR-T
• Description: FULL BRIDGE MOSFET PRE-DRIVER
• Manufacturer: Allegro Microsystems Inc

Specifications of A4940KLPTR-T

• Configuration: H Bridge
• Input Type: Non-Inverting
• Delay Time: 35ns
• Number Of Configurations: 1
• Number Of Outputs: 4
• Voltage - Supply: 5.5 V ~ 50 V
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP Exposed Pad, 24-eTSSOP, 24-HTSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Peak: -
• High Side Voltage - Max (bootstrap): -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 620-1319-2

A4940
FAULT Pin This is an open drain output fault flag, which indi-
cates a fault condition by its state, as shown in table 2. It must be
pulled to V
Fault States
Overtemperature If the junction temperature exceeds the
over-temperature threshold, 170°C typical, the A4940 will enter
the overtemperature fault state and FAULT will go low. The
overtemperature fault state, and FAULT, will only be cleared
when the temperature drops below the recovery level defined by
T
No circuitry will be disabled. External control circuits must take
action to limit the power dissipation in some way so as to prevent
overtemperature damage to the A4940 chip and unpredictable
device operation.
VREG Undervoltage VREG supplies the low-side gate driver
and the bootstrap charge current. It is critical to ensure that the
voltages are sufficiently high before enabling any of the outputs.
If the voltage at VREG, V
undervoltage lockout threshold, V
will enter the VREG undervoltage fault state. In this fault state
FAULT will be low, and the outputs will be disabled. The VREG
undervoltage fault state and the fault flags will be cleared when
VREG rises above the rising VREG undervoltage lockout thresh-
old, V
The VREG undervoltage monitor circuit is active during power-
up, and the A4940 remains in the VREG undervoltage fault state
until VREG is greater than the rising VREG undervoltage lockout
threshold, V
Bootstrap Capacitor Undervoltage The A4940 monitors the
voltage across the individual bootstrap capacitors to ensure they
have sufficient charge to supply the current pulse for the high-
JF
– T
JFHYS
REGUVON
.
DD
REGUVON
with an external resistor, typically 10 to 47 kΩ.
.
.
Table 2. Fault Definitions
*Yes indicates all gate drives low, and all MOSFETs off.
FAULT Pin Setting
REG
High
, drops below the falling VREG
Low
Low
Low
Low
REGUVOFF
, then the A4940
No Fault
Overtemperature
VDD undervoltage
VREG undervoltage
Bootstrap undervoltage
Fault Description
Automotive Full Bridge MOSFET Driver
side drive. Before a high-side drive can be turned on, the voltage
across the associated bootstrap capacitor must be higher than the
turn-on voltage limit. If this is not the case, then the A4940 will
start a bootstrap charge cycle by activating the complementary
low-side drive. Under normal circumstances, this will charge the
bootstrap capacitor above the turn-on voltage in a few microsec-
onds and the high-side drive will then be enabled.
The bootstrap voltage monitor remains active while the high-side
drive is active and, if the voltage drops below the turn-off volt-
age, a charge cycle will be initiated.
In either case, if there is a fault that prevents the bootstrap capaci-
tor charging, then the charge cycle will timeout, FAULT will be
low, and the outputs will be disabled. The bootstrap undervoltage
fault state remains latched until RESET is set low.
VDD Undervoltage The logic supply at VDD is monitored
to ensure correct logical operation. If the voltage at VDD, V
drops below the falling VDD undervoltage lockout threshold,
V
fault state. In this fault state, FAULT will be low, and the outputs
will be disabled. In addition, because the state of other reported
faults cannot be guaranteed, all fault states are reset and replaced
by a VDD undervoltage fault state. For example, a VDD under-
voltage will reset an existing boostrap undervoltage fault condi-
tion and replace it with a VDD undervoltage fault. The VDD
undervoltage fault state and the fault flag will be cleared when
V
defined by V
The VDD undervoltage monitor circuit is active during power-up,
and the A4940 remains in the VDD undervoltage fault state until
V
old, V
DDUVOFF
DD
DD
Disable Outputs*
rises above the rising VDD undervoltage lockout threshold
is greater than the rising VDD undervoltage lockout thresh-
DDUVOFF
Yes
Yes
Yes
No
No
, then the A4940 will enter the VDD undervoltage
DDUVOFF
+V
DDUVHYS
+V
DDUVHYS
Fault Latched
.
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
Yes
No
No
No
–
.
DD
,
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