IC CTRLR PWM STP-DN TRIPL 32WQFN

MAX15048ETJ+

Manufacturer Part NumberMAX15048ETJ+
DescriptionIC CTRLR PWM STP-DN TRIPL 32WQFN
ManufacturerMaxim Integrated Products
MAX15048ETJ+ datasheet
 


Specifications of MAX15048ETJ+

ApplicationsPower Supply Controller, SequencerVoltage - Supply4.7 V ~ 23 V
Current - Supply6mAOperating Temperature-40°C ~ 85°C
Mounting TypeSurface MountPackage / Case32-WQFN Exposed Pad
Number Of Outputs3Output Voltage5 V
Input Voltage4.7 V to 23 VSupply Current6 mA
Switching Frequency200 KHzMounting StyleSMD/SMT
Maximum Operating Temperature+ 85 CMinimum Operating Temperature- 40 C
Lead Free Status / RoHS StatusLead free / RoHS CompliantVoltage - Input-
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COUNT OF 8
IN
CURRENT LIMIT
N
CL
CLR
COUNT OF 3
IN
N
CLR
CLR
Figure 3. Hiccup-Mode Block Diagram
just before the beginning of a new PWM cycle, the con-
troller skips that cycle. During severe overload or short-
circuit conditions, the switching frequency of the device
appears to decrease because the on-time of the low-side
MOSFET extends beyond a clock cycle.
If the current-limit threshold is exceeded for more than
eight cumulative clock cycles (N
CL
down (both DH_ and DL_ are pulled low) for 4096 clock
cycles (hiccup timeout) and then restarts with a soft-
start sequence. If three consecutive cycles pass without
a current-limit event, the count of N
Figure 3). Hiccup mode protects the circuit against a
continuous output short circuit.
Thermal-Overload Protection
The MAX15048/MAX15049 feature an integrated ther-
mal-overload protection with temperature hysteresis.
Thermal-overload protection limits the total power dis-
sipation in the device and protects it in the event of an
extended thermal-fault condition. When the die tempera-
ture exceeds +160NC (typ), an internal thermal sensor
shuts down the device, turning off the power MOSFETs
and allowing the die to cool. After the die temperature
falls by +20NC (typ), the part restarts with a soft-start
sequence.
Design Procedure
Setting the Switching Frequency
Connect a 15.625kI to 93.75kI resistor from RT to
SGND to program the switching frequency from 200kHz
to 1.2MHz. Calculate the switching frequency using the
following equation:
f
(kHz) = 12.8 O R
SW
Higher switching frequencies allow designs with
lower inductor values and less output capacitance.
______________________________________________________________________________________
Triple-Output Buck Controllers
with Tracking/Sequencing
Consequently, peak currents and I
at higher switching frequencies, but core losses, gate-
charge currents, and switching losses increase.
INITIATE HICCUP
TIMEOUT
N
HT
Although the MAX15048/MAX15049 converters can
operate from input supplies ranging from 4.7V to 23V,
the input voltage range can be effectively limited by the
duty-cycle limitations for a given output voltage. The
maximum input voltage is limited by the minimum on-
time (t
ON(MIN)
where t
ON(MIN)
The minimum input voltage is limited by the maximum
duty cycle and is calculated using the following equa-
tion:
), the device shuts
where t
OFF(MIN)
is cleared (see
CL
Three key inductor parameters must be specified for
operation with the MAX15048/MAX15049: inductance
value (L), inductor saturation current (I
tor series resistance (DCR). The minimum required
inductance is a function of operating frequency, input-to-
output voltage differential, and the peak-to-peak inductor
current (DI
value. A lower inductance value minimizes size and
cost and improves large-signal and transient response.
However, efficiency is reduced due to higher peak cur-
rents and higher peak-to-peak output-voltage ripple for
the same output capacitor. A higher inductance increas-
es efficiency by reducing the ripple current; however,
resistive losses due to extra wire turns can exceed the
benefit gained from lower ripple current levels, especial-
ly when the inductance is increased without also allow-
ing for larger inductor dimensions. A good rule of thumb
is to choose DI
Calculate the inductance using the following equation:
(kI)
RT
V
and V
IN
optimum for typical conditions. The switching frequency
2
R losses are lower
Effective Input Voltage Range
):
V
OUT_
V
IN(MAX)
t
×
f
ON(MIN)
SW
is 75ns.
V
OUT_
=
V
IN(MIN)
1-(t
×
f
)
OFF(MIN)
SW
typically is equal to 300ns.
Inductor Selection
), and induc-
SAT
). Higher DI
allows for a lower inductor
P-P
P-P
equal to 30% of the full load current.
P-P
V
(V
- V
)
OUT_
IN
OUT_
L
=
×
× ∆
V
f
I
IN
SW
P-P
are typical values so that efficiency is
OUT_
19