MOSFET gate drivers with negative Vgs capability

[Winfield Hill]

NSC has introduced a power MOSFET gate driver, the LM5110-1,
which has an extra power-supply pin that can be operated at
ground or as low as -5 volts. This is the low-side voltage
of the FET gate driver, so the gate can be driven up to 5V
below ground. http://www.national.com/pf/LM/LM5110.html

NSC announced the LM5110-1 as the "Industry's first dual 5A
MOSFET gate driver with negative Vgs capability," which is
a statement with quite a few qualifiers. My question, are
there any other gate driver ICs with a negative Vgs supply
pin? Some driver ICs allow the FET source to go negative
for a short time, such as Intersil's HIP4080 series, but I
can't recall another high-current driver IC with a -Vee pin.

Thanks,
- Win

whill_at_picovolt-dot-com

 

[Fritz Schlunder]

NSC has introduced a power MOSFET gate driver, the LM5110-1,
which has an extra power-supply pin that can be operated at
ground or as low as -5 volts. This is the low-side voltage
of the FET gate driver, so the gate can be driven up to 5V
below ground. http://www.national.com/pf/LM/LM5110.html

NSC announced the LM5110-1 as the "Industry's first dual 5A
MOSFET gate driver with negative Vgs capability," which is
a statement with quite a few qualifiers. My question, are
there any other gate driver ICs with a negative Vgs supply
pin? Some driver ICs allow the FET source to go negative
for a short time, such as Intersil's HIP4080 series, but I
can't recall another high-current driver IC with a -Vee pin.

Thanks,
- Win

whill_at_picovolt-dot-com

Yay! Good for National Semiconductor, pat yourselves on the back NatSemi.
This part definitely appears to be a step in the right direction. This part
doesn't sound quite like the holy grail of MOSFET/IGBT gate drivers in my
mind, but it is better than anything I've seen so far at least.

What I would like to see is a part that has internal voltage regulators and
charge pumps to produce gate drive of +17V on and -10V off all from a single
rail supply voltage of anywhere between say 4V and 50V unregulated (okay
maybe that range is a bit large, but something decent would be nice).
Ideally the output would not be using a single pin either, but a two pin
design. One pin would do the sourcing current and the other would sink
current. That way the engineer could use independent value gate resistors
for custom tailored non-symmetric pull up/down capability. In some cases it
may be advantageous to turn on the MOSFET/IGBT slowly to reduce diode
reverse recovery currents for instance, but then in the same case turn off
very fast to minimize switching loss. Oh yeah, and the gate driver should
come in a tiny package (but also have a DIP version available) and be dirt
cheap and widely available. The device should also be fully protected from
damage even if the MOSFET/IGBT it is driving fails and hundreds of volts
with very high current capability start coming out of the gate and gets
applied to the driver output. It would also be nice if the device wouldn't
care in the slightest if you use a current sense resistor in the MOSFET
source, even when large voltages appear across the resistor. Latchup
immunity is also a must.

While I'm dreaming I might as well ask for another version incorporating all
the above features plus full galvanic isolation with its own internal
floating power source. The device should have very short balanced
propagation delays (say <70ns) and operate from full DC up to 1 MHz or
greater frequencies. Of course this device needs to be small, dirt cheap,
and widely available as well.

Maybe someday... But until then thanks for making me aware of this new
NatSemi offering.

 

[Harry Dellamano]

NSC has introduced a power MOSFET gate driver, the LM5110-1,
which has an extra power-supply pin that can be operated at
ground or as low as -5 volts. This is the low-side voltage
of the FET gate driver, so the gate can be driven up to 5V
below ground. http://www.national.com/pf/LM/LM5110.html

NSC announced the LM5110-1 as the "Industry's first dual 5A
MOSFET gate driver with negative Vgs capability," which is
a statement with quite a few qualifiers. My question, are
there any other gate driver ICs with a negative Vgs supply
pin? Some driver ICs allow the FET source to go negative
for a short time, such as Intersil's HIP4080 series, but I
can't recall another high-current driver IC with a -Vee pin.

Thanks,
- Win

whill_at_picovolt-dot-com

Hi Win,
This is the only driver that I know of that offers a -Vee. It is usable
with low threshold FETS but with 5A capability you would like to use it with
higher threshold devices. With a 15V max Vcc to Vee rating, backed off to 12
or 13 V max for safe operation, and -3Vee, that only leaves 9V for
enhancement. For large power jobs I would rather run Vcc at 15V and get the
lower Ron of the device. If Vcc-Vee was 22V, we would have a great driver.

my $0.02
harry

 

[Fritz Schlunder]

Oh yeah. Forgot to mention the drivers should also include high impedance
inputs with hysteresis and a switching threshold around 3V, but tolerant of
input voltages up to say 20V independent of the positive supply voltage.
The input should be very well buffered such that even if someone
accidentally or deliberately applies an analog input voltage the output will
be guaranteed to be fully high or fully low. Low supply current and low
packaging thermal resistance would also be nice.

 

[John Larkin]

NSC has introduced a power MOSFET gate driver, the LM5110-1,
which has an extra power-supply pin that can be operated at
ground or as low as -5 volts. This is the low-side voltage
of the FET gate driver, so the gate can be driven up to 5V
below ground. http://www.national.com/pf/LM/LM5110.html

NSC announced the LM5110-1 as the "Industry's first dual 5A
MOSFET gate driver with negative Vgs capability," which is
a statement with quite a few qualifiers. My question, are
there any other gate driver ICs with a negative Vgs supply
pin? Some driver ICs allow the FET source to go negative
for a short time, such as Intersil's HIP4080 series, but I
can't recall another high-current driver IC with a -Vee pin.

Thanks,
- Win

whill_at_picovolt-dot-com

Any old driver can be run with the "ground" pin negative and the logic
input suitably shifted; it's not often that anybody cared.

Forget all these "features" people keep adding; what I want is a
*fast* driver.

John

 

[Mikko Syrjalahti]

NSC announced the LM5110-1 as the "Industry's first dual 5A
MOSFET gate driver with negative Vgs capability," which is
a statement with quite a few qualifiers. My question, are
there any other gate driver ICs with a negative Vgs supply
pin? Some driver ICs allow the FET source to go negative
for a short time, such as Intersil's HIP4080 series, but I
can't recall another high-current driver IC with a -Vee pin.

Elantec EL7457 comes to mind of the components I've used.
Only 2A, but with 4 channels.

 

[Winfield Hill]

Mikko Syrjalahti wrote...

Elantec EL7457 comes to mind of the components I've used.
Only 2A, but with 4 channels.

Thanks! 40MHz ATE pin drivers. And the EL7155 and EL7156.

Thanks,
- Win

whill_at_picovolt-dot-com