MAX15046BAEE+T Maxim Integrated Products, MAX15046BAEE+T Datasheet - Page 19

• Manufacturer Part Number: MAX15046BAEE+T
• Description: IC CTLR SYNC BUCK 40V 16-QSOP
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck)r

Specifications of MAX15046BAEE+T

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 0.6 ~ 34 V
• Current - Output: 3A
• Frequency - Switching: 100kHz ~ 1MHz
• Voltage - Input: 4.5 ~ 40 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Power - Output: 771.5mW
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 4. Type III Compensation Network
overall thermal budget. Ensure that the DL gate driver
can drive the low-side MOSFET. In particular, check
that the dv/dt caused by the high-side MOSFET turning
on does not pull up the low-side MOSFET gate through
the drain-to-gate capacitance of the low-side MOSFET,
which is the most frequent cause of crossconduction
problems.
Check power dissipation when using the internal linear
regulator to power the gate drivers. Select MOSFETs
with low gate charge so that V
without overheating the device:
where Q
two external MOSFETs.
The MAX15046 uses a bootstrap circuit to generate
the necessary gate-to-source voltage to turn on the
high-side MOSFET. The selected n-channel high-side
MOSFET determines the appropriate boost capacitance
value (C
ing to the following equation:
where Q
MOSFET and DV
on the high-side MOSFET driver after turn-on. Choose
DV
significantly degraded (e.g. DV
when determining C
BST
C
R
I
I
such that the available gate-drive voltage is not
BST
G_TOTAL
Boost Capacitor and Diode Selection
G
P
is the total gate charge of the high-side
R
R
DRIVE
in the Typical Application Circuits) accord-
1
2
V
OUT
______________________________________________________________________________________
BST
is the sum of the gate charges of the
= V
BST
C
V
REF
BST
CC
is the voltage variation allowed
.
40V, High-Performance, Synchronous
x Q
=
∆
R
CC
G_TOTAL
V
g
Q
F
M
BST
BST
C
G
CF
can power both drivers
= 100mV to 300mV)
C
F
x f
SW
COMP
Use a low-ESR ceramic capacitor as the boost capacitor
with a minimum value of 100nF.
A small-signal diode can be used for the bootstrap cir-
cuit and must have a minimum voltage rating of V
3V to withstand the maximum BST voltage. The average
forward current of the diode should meet the following
requirement:
where Q
The maximum power dissipation of the device depends
on the thermal resistance from the die to the ambient
environment and the ambient temperature. The thermal
resistance depends on the device package, PCB copper
area, other thermal mass, and airflow.
The power dissipated into the package (P
on the supply configuration (see the Typical Application
Circuits). Use the following equation to calculate power
dissipation:
where I
frequency. See the I
the Typical Operating Characteristics for the I
Use the following equation to estimate the temperature
rise of the die:
where B
of the package, P
and T
for the 16-pin QSOP and 44NC/W for the 16-pin QSOP-
EP package on multilayer boards, with the conditions
specified by the respective JEDEC standards (JESD51-5,
JESD51-7). An accurate estimation of the junction tem-
perature requires a direct measurement of the case
temperature (T
significantly deviate from those described in the JEDEC
standards. The junction temperature is then:
Use 37NC/W as B
QSOP package and 6NC/W for the 16-pin QSOP-EP
package. The case-to-ambient thermal impedance (B
is dependent on how well the heat is transferred from the
PCB to the ambient. Use large copper areas to keep the
PCB temperature low.
A
Q
is the ambient temperature. The B
JA
GATE
is the quiescent supply current at the switching
P
is the junction-to-ambient thermal impedance
T
is the gate charges of the low-side MOSFET.
= V
C
) when actual operating conditions
Buck Controller
IN
T
T
JC
T
J
J
I
F
IN
x [Q
= T
= T
is power dissipated in the device,
thermal impedance for the 16-pin
> Q
vs. Switching Frequency graph in
C
A
G_TOTAL
GATE
+ (P
+ (P
T
T
x f
x B
x B
Power Dissipation
SW
x f
JA
JC
SW
)
)
+ I
JA
Q
is 103.7NC/W
T
]
) depends
Q
.
IN
CA
19
+
)