AAT4901IJS-1-T1 ANALOGICTECH [Advanced Analogic Technologies], AAT4901IJS-1-T1 Datasheet - Page 10

• Manufacturer Part Number: AAT4901IJS-1-T1
• Description: Buffered Power Full-Bridge
• Manufacturer: ANALOGICTECH [Advanced Analogic Technologies]

The relationship between C
given by:
Eq. 5:
The peak current drive requirements for a given MOSFET
gate voltage can be derived from Equations 4 and 5:
Eq. 6:
Design Example
V
V
F
θ
I
T
T
t
10
FastSwitch
QAC
RISE
SW
A
JA
J(MAX)
IN
GATE
Q
= 85°C
= 225°C/W
= 5V
G(MAX)
= 1MHz
= 4.0mA
= dt = 10ns
= 5V
= 120°C
C
I
G(MAX)
G(MAX)
=
2 · 1MHz
C
I
G(MAX)
=
G(MAX)
=
1
TM
Q
Q
G(MAX)
V
dt
G(MAX)
GATE
=
=
·
Q
Q
⎛
⎝
V
225°C/W · 5V
G(MAX)
120°C - 85°C
G(MAX)
dt
GATE
=
=
G(MAX)
13.6nC
13.6nC
10ns
5V
, Q
= 1.36A
- 4.0mA = 13.6nC
G(MAX)
= 2.7nF
, and V
⎞
⎠
w w w . a n a l o g i c t e c h . c o m
GATE
is
Typical Applications
2-Phase Synchronous Buck Converter
The most common AAT4901 applications include multi-
phase DC/DC converter output power stages, DC motor
drive, a dual low-side MOSFET driver, and a 3-state high-
speed high-current line driver.
Figure 2 shows a typical configuration when used as a
2-phase buck converter power stage with synchronous
rectification. The EN pin can be used to force outputs
OUTA/OUTB to a high impedance state; this allows the
output inductor to operate in discontinuous condition
mode (DCM) and improves efficiency under light load
conditions. The body diode associated with the low-side
switching device gives the AAT4901 inductive switching
capability, and clamps the LX node at one diode drop
below GND during the break-before-make time. The
multiphase buck converter assures a stable, high-perfor-
mance topology for high currents and low voltages which
are demanded in computers, workstation, telecom and
datacom servers. Figure 3 illustrates output ripple cur-
rent reduction due to 2-phase cancellation.
Motor Drive
The AAT4901 is ideally suited for use as an efficient out-
put driver for DC brushless motor control due to its full
bridge output stage with integrated MOSFETs. The induc-
tive load switching capability of the AAT4901 eliminates
the need for external diodes during commutation time.
In applications where rotation is always in the same
direction, a single half-bridge AAT4900 can be used to
drive a DC motor. If needed to control the rotation in
both directions, full-bridge motor control circuits can be
applied as shown in Figure 4. In this configuration the
motor can be controlled to run clockwise, counter-clock-
wise, stop rapidly (“regeneration” braking) or free run
(coast) to a stop.
Buffered Power Full-Bridge
PRODUCT DATASHEET
AAT4901
4901.2008.03.1.0