SI9976DY Vishay, SI9976DY Datasheet - Page 5

• Manufacturer Part Number: SI9976DY
• Description: N-CH HALF BRIDGE DRIVER
• Manufacturer: Vishay
• Type: High Side/Low Sider

Specifications of SI9976DY

• Rohs Compliant: NO
• Rise Time: 110 ns
• Fall Time: 50 ns
• Supply Voltage (min): 20 V
• Supply Current: 10 mA
• Maximum Power Dissipation: 1000 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SO-14
• Bridge Type: Half Bridge
• Minimum Operating Temperature: - 40 C
• Number Of Drivers: 2
• Number Of Outputs: 2
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

DETAILED DESCRIPTION
Power On Conditioning
Bootstrap-type floating supplies require that the bootstrap
capacitor be charged at power on. In the case of the Si9976,
this is accomplished by pulsing the IN line low with the EN line
held high, thus turning on the low-side MOSFET and providing
the charging path for the capacitor.
Operating Voltage: 20 to 40 V
The Si9976 is intended to be powered by a single power
supply within the range of 20 to 40 V and is designed to drive
a totem pole pair of NMOS power transistors such as those
within the Si9955. The power transistors must be powered by
the same power supply as this driver. In addition to the
high-voltage power supply (20 to 40 V), the Si9976 must have
a power supply connected to the V
signal is desired.
voltage for the fault output and allows the high output voltage
level to be compatible with system logic that monitors the fault
condition. The value of this power supply must be within the
range of 4.5 to 16.5 V to ensure functionality of the output.
Internal fault circuitry, which is used for shorted-load
protection, is not affected by this power supply.
Cross-Conduction Protection
The high-side power transistor can only be turned on after a
fixed time delay following the return to ground of the low-side
power transistor’s gate. The low-side transistor can only be
turned on after a fixed time delay following the high-side
transistor turn-off signal.
Undervoltage Lockout
During power up, both power transistors are held off until the
internal regulated power supply, V
V
undervoltage lockout circuitry continues to monitor V
undervoltage condition occurs, both the high-side and
low-side transistors will be turned off and the fault output will be
set high. When the undervoltage condition no longer exists,
normal function will resume automatically. Separate voltage
sensing of the bootstrap capacitor voltage allows a turn-on
signal to be sent to the high-side drive circuit if either the
bootstrap capacitor has full voltage, or the load voltage is high
(driven high by an inductive load or shorted high). The voltage
sensing circuit will allow the high-side power transistor to turn
on if an on signal is present and the voltage on the bootstrap
capacitor rises from undervoltage to operating voltage.
Document Number: 70016
S-40757—Rev. F, 19-Apr-04
be
from the final value, nominally 16 V. After power up, the
This power supply provides operating
CC
DD
terminal, if a fault output
, is approximately one
DD
. If an
Short Circuit Protection
This device is intended to be used only in a half-bridge which
drives inductive loads. A shorted load is presumed if the load
voltage does not make the intended transition within an
allotted time.
transitions. A longer time is allowed for the high-side to turn on
(300 ns vs. 200 ns) since the propagation delays are longer.
Excessive capacitive loading can be interpreted as a short.
The value of capacitance that is needed to produce the
indication of a short depends on the load driving capability of
the power transistors.
ESD Protection
Electrostatic discharge protection devices are between V
and GND, V
FAULT to both V
ESD protected.
Fault Feedback
Detection of a shorted load sets a latch which turns off both the
high-side and the low-side power transistors. If V
a one level will be present on the FAULT output. To reset the
system, the enable input, EN, must be lowered to a logic zero
and then raised to a logic one. The logic level of the input, IN,
will determine which power transistor will be turned on first after
reset. An undervoltage condition on V
causes a one level on the FAULT output, if V
Static (dc) Operation
All components of a charge pump, except the holding
(bootstrap) capacitor, are included in the circuit. This charge
pump will provide current that is sufficient to overcome any
leakage currents which would reduce the enhancement
voltage of the high-side power transistor while it is on. This
allows the high-side power transistor to be on continuously.
When the low-side power transistor is turned on, additional
charge is restored to the bootstrap capacitor, if needed. The
maximum switching speed of the system at 50% duty cycle is
limited by the on time of the low-side power transistor. During
this time, the bootstrap capacitor charge must be restored.
However, if the duty cycle is skewed so that the on time of the
high-side power transistor is long enough for the charge pump
to completely restore the charge lost during switching, then the
on time of the low-side power transistor is not restricted.
CC
and GND, and from terminals IN, EN, G2, and
Separate timing is provided for the two
DD
and GND. V+, CAP, S1, and G1 are not
Vishay Siliconix
DD
is not latched, but
CC
CC
www.vishay.com
is present.
Si9976
is present,
DD
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