Datasheet
MAX17491
Single-Phase Synchronous MOSFET Driver
_______________________________________________________________________________________
5
Pin Description
PIN NAME FUNCTION
1 BST
Boost Flying-Capacitor Connection. Gate-drive power supply for DH high-side gate driver. Connect a
0.1μF or 0.22μF capacitor between BST and LX.
2 PWM
PWM Input. Noninverting DH control input from the controller IC:
Logic-high: DH = high (BST), DL = low (PGND).
Midlevel: After the midlevel hold time expires, the controller enters standby mode. DH and DL pulled
low.
Logic-low: DH = low (LX), DL = high (V
DD
) when SKIP = high.
Internal pullup and pulldown resistors create the midlevel and prevent the controller from triggering an
on-time if this input is left unconnected (not soldered properly) or driven by a high impedance.
3 GND Power Ground for the DL Gate Drivers and Analog Ground. Connect exposed pad to GND.
4 DL PWM Low-Side Gate-Driver Output. Swings between GND and V
DD
. DL forced high in shutdown.
5 V
DD
Supply Voltage Input for the DL Gate Drivers. Connect to 4.2V to 5.5V supply and bypass to GND with a
1μF ceramic capacitor.
6 SKIP
Active-Low Pulse-Skipping Mode. Enable pulse-skipping mode (zero-crossing comparator enabled) when
the driver is operating in SKIP mode:
SKIP = V
DD
PWM mode
SKIP = GND skip mode
An internal pulldown current pulls the controller into the low-power pulse-skipping state if this input is
left unconnected (not soldered properly) or driven by a high impedance.
7 LX
Switching Node and Inductor Connection. Low-power supply for the DH high-side gate driver. LX
connects to the skip-mode zero-crossing comparator.
8 DH External High-Side n-Channel MOSFET Gate-Driver Output. Swings between LX and BST.
— EP Exposed Pad. Connect to ground through multiple vias to reduce the thermal impedance.
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
DD
= 5V, C
DH
= 3nF, C
DL
= 3nF, T
A
= +25°C, unless otherwise noted.)
SWITCHING WAVEFORMS
(PWM = MID TO LOW TO MID)
MAX17491 toc11
V
PWM
V
DL
V
DH
V
LX
0
0
0
5V
5V/div
5V/div
10V/div
0
10V/div
5V
SWITCHING WAVEFORMS
(PWM = HIGH TO MID TO HIGH)
MAX17491 toc12
V
PWM
V
DL
V
DH
V
LX
0
0
10V
0
0
5V
5V/div
5V/div
10V/div
15V
10V/div