MAX5078AATT-T Maxim Integrated Products, MAX5078AATT-T Datasheet - Page 9

• Manufacturer Part Number: MAX5078AATT-T
• Description: MOSFET & Power Driver ICs 4A 20ns MOSFET Driver
• Manufacturer: Maxim Integrated Products
• Type: Low Sider

Specifications of MAX5078AATT-T

• Rise Time: 85 ns
• Fall Time: 75 ns
• Supply Voltage (min): 4 V
• Supply Current: 0.04 mA
• Maximum Power Dissipation: 1454 mW
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Maximum Turn-off Delay Time: 35 ns
• Maximum Turn-on Delay Time: 35 ns
• Minimum Operating Temperature: - 40 C
• Number Of Drivers: 1
• Number Of Outputs: 1

Use the following equation to calculate the series resistor:
L
L
FET vendor.
Pay extra attention to bypassing and grounding the
MAX5078A/MAX5078B. Peak supply and output currents
may exceed 4A when driving large external capacitive
loads. Supply voltage drops and ground shifts create
negative feedback for inverters and may degrade the
delay and transition times. Ground shifts due to poor
device grounding may also disturb other circuits sharing
the same AC ground return path. Any series inductance
in the V
tions due to the very high di/dt when switching the
MAX5078A/MAX5078B with any capacitive load. Place
one or more 0.1µF ceramic capacitors in parallel as close
to the device as possible to bypass V
ground plane to minimize ground return resistance and
series inductance. Place the external MOSFET as close
as possible to the MAX5078A/MAX5078B to further mini-
mize board inductance and AC path impedance.
Power dissipation of the MAX5078A/MAX5078B consists
of three components: caused by the quiescent current,
capacitive charge/discharge of internal nodes, and the
output current (either capacitive or resistive load).
Maintain the sum of these components below the maxi-
mum power dissipation limit.
Figure 1. Timing Diagram
P
S
OUT
RISING MISMATCH = t
FALLING MISMATCH = t
IN+
IN-
can be approximated as 2nH for the TDFN package.
is on the order of 20nH/in. Verify L
V
V
IH
IL
DD
, OUT, and/or GND paths can cause oscilla-
R
GATE
Supply Bypassing and Grounding
t
t
D-OFF2
D-OFF1
D-ON2
D-OFF2
- t
_______________________________________________________________________________________
D-ON1
- t
D-OFF1
(
L
P
t
F
C
L
V
IL
S
G
Power Dissipation
L
V
G
IH
)
DD
t
t
D-ON2
D-ON1
G
R
ON
to GND. Use a
with the MOS-
90%
10%
t
R
4A, 20ns, MOSFET Driver
The current required to charge and discharge the inter-
nal nodes is frequency dependent (see the I
Supply Current vs. Supply Voltage graph in the Typical
Operating Characteristics). The power dissipation (P
due to the quiescent switching supply current (I
can be calculated as:
For capacitive loads, use the following equation to esti-
mate the power dissipation:
where C
voltage, and f
Calculate the total power dissipation (P
Use the following equations to estimate the MAX5078A/
MA5078B total power dissipation when driving a ground-
referenced resistive load:
where D is the fraction of the period the MAX5078A/
MA5078B’s output pulls high, R
on-resistance of the device with the output high, and
I
MAX5078B.
The MAX5078A/MAX5078B MOSFET drivers source and
sink large currents to create very fast rising and falling
edges at the gate of the switching MOSFET. The high
di/dt can cause unacceptable ringing if the trace
lengths and impedances are not well controlled.
Figure 2. MAX5054 Simplified Diagram (1 Driver)
LOAD
IN+
IN-
is the output load current of the MAX5078A/
LOAD
P
P
RLOAD
MAX5078A
MAX5078B
CLOAD
SW
is the capacitive load, V
is the switching frequency.
P
P
P
= D x R
Q
T
T
= C
= P
= P
= V
LOAD
Q
Q
DD
+ P
+ P
ON(MAX)
x I
x (V
CLOAD
RLOAD
CONTROL
DD-SW
Layout Information
BEFORE-
ON(MAX)
BREAK-
MAKE
DD
x I
)
2
LOAD
x f
T
DD
) as follows:
is the maximum
SW
is the supply
2
P
N
DD-SW
DD-SW
V
OUT
GND
DD
Q
9
)
)