MAX15048ETJ+ Maxim Integrated Products, MAX15048ETJ+ Datasheet - Page 17

IC CTRLR PWM STP-DN TRIPL 32WQFN

MAX15048ETJ+

Manufacturer Part Number
MAX15048ETJ+
Description
IC CTRLR PWM STP-DN TRIPL 32WQFN
Manufacturer
Maxim Integrated Products
Datasheet

Specifications of MAX15048ETJ+

Applications
Power Supply Controller, Sequencer
Voltage - Supply
4.7 V ~ 23 V
Current - Supply
6mA
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
32-WQFN Exposed Pad
Number Of Outputs
3
Output Voltage
5 V
Input Voltage
4.7 V to 23 V
Supply Current
6 mA
Switching Frequency
200 KHz
Mounting Style
SMD/SMT
Maximum Operating Temperature
+ 85 C
Minimum Operating Temperature
- 40 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Voltage - Input
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
DREG_ is the supply input for the low-side MOSFET
driver. Connect DREG_ to REG externally. Every time
the low-side MOSFET switches on, high peak current
is drawn from DREG_ for a short time. Adding an RC
filter (1I to 4.7I and 220nF ceramic capacitors are
typical) from REG to DREG_ filters out these high-peak
currents. Alternatively, DREG_ can be connected to an
external source (V
age should be high enough to fully enhance the low-side
MOSFET. To avoid partial enhancing of the MOSFETs,
use V
BST_ supplies the power for the high-side MOSFET drivers.
The MAX15048/MAX15049 consist of an internal switch
between DREG_ and BST_ to boost DH_ voltage above
V
turn on the high-side MOSFET. Connect a bootstrap
0.1FF or higher ceramic capacitor between BST_ and
LX_.
The high-side (DH_) and low-side (DL_) drivers drive the
gates of the external n-channel MOSFETs. The drivers’
1A peak source-and-sink-current capability provides
ample drive for the fast rise and fall times of the switch-
ing MOSFETs. Faster rise and fall times result in reduced
switching losses.
The gate-driver circuitry also provides a break-before-
make time (35ns typ) to prevent shoot-through currents
during transition.
The enable input (EN_) in conjunction with digital soft-
start and soft-stop provide coincident/ratiometric track-
ing. Track an output voltage by connecting a resistive
voltage-divider from the output being tracked to the
enable/tracking input. For example, for V
cidentally track V
voltage-divider used for FB2 from OUT1 to EN2
to SGND. See Figure 2 and the Typical Operating
Characteristics (Coincident Tracking).
Track ratiometrically by connecting EN_ to SGND. This
synchonizes the soft-start and soft-stop of all the control-
lers’ references, and hence their respective output volt-
ages track ratiometrically. See Figure 2 and the Typical
Operating Characteristics (Ratiometric Tracking).
For the MAX15048, the output short-circuit fault situa-
tions at master or slave outputs are handled carefully
IN
, providing the necessary gate-to-source voltage to
DREG-EXT
to set the UVLO externally using EN1.
______________________________________________________________________________________
DREG-EXT
OUT1
Ratiometric Tracking (EN_)
MOSFET Gate Drivers and
, connect the same resistive
MAX15048 Coincident/
). Note that the DREG_ volt-
Internal Boost Switch
Triple-Output Buck Controllers
OUT2
to coin-
with Tracking/Sequencing
Figure 1. Graphical Representation of Coincident Tracking,
Ratiometric Tracking (MAX15048), or Sequencing (MAX15049)
so that either the master or slave output does not stay
on when the other outputs are shorted to ground. When
the slave is shorted and enters in hiccup mode, both
the master and the other slave soft-stop. When the
master is shorted and the part enters hiccup mode, the
slaves ratiometrically soft-stop. Coming out of the hic-
cup, all outputs soft-start coincidently or ratiometrically
depending on their initial configuration. See the Typical
Operating Characteristics for the output behavior dur-
ing the fault conditions. During the thermal shutdown or
power-off when the input falls below its UVLO, the output
voltages fall down at a rate depending on the respective
output capacitor and load.
See Figure 1 for a graphical representation of coinci-
dent/ratiometric tracking (MAX15048) or sequencing
(MAX15049).
SOFT-START
* THE FALLING EDGES OF THE MAX15049 DEPEND ON THE LOAD CURRENT.
SOFT-START
SOFT-START
b) RATIOMETRIC TRACKING OUTPUTS
a) COINCIDENT TRACKING OUTPUTS
c) SEQUENCED OUTPUTS*
V
V
V
V
V
V
V
V
V
OUT1
OUT2
OUT3
OUT1
OUT2
OUT3
OUT1
OUT2
OUT3
SOFT-STOP
SOFT-STOP
17

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