MAX15054 Maxim Integrated Products, MAX15054 Datasheet - Page 7

• Manufacturer Part Number: MAX15054
• Description: High-Side MOSFET Driver
• Manufacturer: Maxim Integrated Products

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The MAX15054 drives an external high-side MOSFET.
Both the high- and low-side supplies feature separate
UVLO protection that monitors each driver’s input supply
voltage (BST-LX and V
threshold (V
the driver output low when V
irrespective of the high-side UVLO condition.
The high-side driver UVLO threshold (V
referenced to LX, and pulls HDRV low when V
below 3.6V (typ) with respect to LX. After the MAX15054 is
first energized (V
(C
does not switch since the BST-to-LX voltage is below
V
BST-LX supply through an external Schottky diode and
within a short time C
V
and follows HI. The hysteresis is 0.2V (typ) for both UVLO
thresholds.
The MAX15054 driver contains low on-resistance
p-channel and n-channel devices in a totem pole
configuration for the driver output stage. This allows for
rapid turn-on and turn-off of high gate-charge (Qg)
external switching MOSFETs. The driver exhibits low
drain-to-source resistance (R
lower operating temperatures. Lower R
higher source and sink currents from the device as
the external MOSFET gate capacitance charges and
discharges at a quicker rate, resulting in faster switching
speeds. The peak source and sink current provided by
the driver is 2.5A (typ).
Propagation delay from the logic input (HI) to the driver
output is 12ns (typ)
contains break-before-make logic to eliminate shoot-
through conditions that cause unnecessarily high
operating supply currents, efficiency reduction, and
voltage spikes at V
Voltage from HDRV to LX is approximately equal to V
minus the diode drop of the bootstrap diode when in a
high state, and zero when in a low state.
BST_UVLO
BST
BST
) between BST and LX is not charged, and HDRV
to exceed V
High-Side MOSFET Driver for HB LED Drivers
. An internal charging circuit charges the
DD_UVLO
DD
_______________________________________________________________________________________
BST_UVLO
DD
BST
> V
(Figure
) is referenced to GND and pulls
.
DD_UVLO
DD
charges through V
). The low-side supply UVLO
. HDRV then starts switching
1). The internal driver also
DS(ON)
DD
Undervoltage Lockout
), the bootstrap capacitor
falls below 4V (typ)
) that decreases for
Output Driver
DS(ON)
DD
BST_UVLO
and causes
BST
means
) is
falls
DD
and DC-DC Applications
Connect an external Schottky diode between V
BST, in conjunction with an external bootstrap capacitor
(C
MOSFET (see the Typical Operating Circuits). The diode
charges the bootstrap capacitor from V
high-side switch is off, and isolates V
pulled high when the driver turns on.
The bootstrap capacitor (C
used to ensure adequate charge is available to switch
the high-side MOSFET. This capacitor is charged from
V
is off. The bootstrap capacitor value should be selected
carefully to avoid oscillations during turn-on and turn-
off at the HDRV output. Choose a capacitor value at
least 20 times greater than the total gate capacitance
of the MOSFET being switched. Use a low-ESR ceramic
capacitor (typically a minimum 0.1FF is needed). The
high-side MOSFET’s continuous on-time is limited due
to the charge loss from the high-side driver’s quiescent
current. The maximum on-time is dependent on the size
of C
The MAX15054 features a 5V CMOS logic input. The
required logic-input levels are independent of V
are capable of withstanding up to 13.5V. For example,
the MAX15054 can be powered by a 5V supply while the
logic inputs are provided from 12V logic. Additionally, HI
is protected against voltage spikes up to 15V, regardless
of the V
to avoid double pulsing during signal transition. The logic
input is a high-impedance input (300kI, typ) and should
not be left unconnected to ensure the input logic state is
at a known level. With the logic input unconnected, HDRV
pulls low as V
PWM output from the controller must assume a proper
state while powering up the device.
DD
BST
BST
by an external bootstrap diode when the MOSFET
), to provide the voltage required to turn on the
DD
, I
BST
voltage. The logic input has 900mV hysteresis
(125FA, max), and V
DD
rises above the UVLO threshold. The
BST
) between BST and LX is
Driver Logic Input (HI)
Bootstrap Capacitor
BST_UVLO
Bootstrap Diode
DD
when HDRV is
DD
.
when the
DD
DD
and
and
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