MAX8791BGTA+T Maxim Integrated Products, MAX8791BGTA+T Datasheet - Page 8

• Manufacturer Part Number: MAX8791BGTA+T
• Description: IC MOSF DRIVER 1PH SYNCH 8TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8791BGTA+T

• Configuration: High and Low Side, Synchronous
• Input Type: Differential
• Delay Time: 14ns
• Current - Peak: 2.7A
• Number Of Configurations: 1
• Number Of Outputs: 2
• High Side Voltage - Max (bootstrap): 36V
• Voltage - Supply: 4.2 V ~ 5.5 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 8-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Single-Phase, Synchronous MOSFET Drivers
The DH and DL drivers are optimized for driving mod-
erately sized high-side and larger low-side power
MOSFETs. This is consistent with the low duty factor
seen in the notebook CPU environment, where a large
V
circuits monitor the DH and DL outputs and prevent the
opposite-side FET from turning on until the other is fully
off. The MAX8791/MAX8791B constantly monitor the
low-side driver output (DL) voltage, and only allow the
high-side driver to turn on when DL drops below the
adaptive threshold. Similarly, the controller monitors the
high-side driver output (DH), and prevents the low side
from turning on until DH falls below the adaptive thresh-
old before allowing DL to turn on.
The adaptive driver dead time allows operation without
shoot-through with a wide range of MOSFETs, minimiz-
ing delays and maintaining efficiency. There must be a
low-resistance, low-inductance path from the DL and
DH drivers to the MOSFET gates for the adaptive dead-
time circuits to work properly; otherwise, the sense cir-
cuitry in the MAX8791/MAX8791B interprets the
Figure 4. Overview Block Diagram
8
IN
_______________________________________________________________________________________
- V
PWM
SKIP
OUT
differential exists. Two adaptive dead-time
V
DD
Adaptive Shoot-Through Protection
THERMAL SHUTDOWN
UVLO
LX
DRIVER LOGIC
DEAD-TIME
PAD
CONTROL
DRV#
AND
ZX DETECTION
MOSFET gates as off while charge actually remains.
Use very short, wide traces (50 mils to 100 mils wide if
the MOSFET is 1in from the driver).
The MAX8791/MAX8791B use a bootstrap circuit to
generate the necessary drive voltage to fully enhance
the high-side n-channel MOSFET. The internal p-chan-
nel MOSFET creates an ideal diode, providing a low
voltage drop between V
The selected high-side MOSFET determines appropriate
boost capacitance values (C
to the following equation:
where Q
MOSFET and ∆V
the high-side MOSFET driver. Choose ∆V
0.2V when determining C
should be a low equivalent-series resistance (ESR)
ceramic capacitor.
GATE
is the total gate charge of the high-side
DRV
BST
C
BST
is the voltage variation allowed on
=
DD
Q
BST
GATE
and BST.
Internal Boost Switch
. The boost flying capacitor
BST
∆
in Figure 1), according
V
BST
BST
= 0.1V to
LX
DL
BST
DH
GND
V
DD