Datasheet

MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
10 ______________________________________________________________________________________
Pin Description
PIN
MAX8597
MAX8598/
MAX8599
NAME
FUNCTION
1 1 AVL
Filtered VL Input. Connect to VL through a 10Ω resistor. Bypass to GND with a 0.22µF or larger
ceramic capacitor.
2—
REFIN
External Reference Input. FB tracks the voltage input to REFIN. Connect REFIN to AVL to use
the internal 0.6V reference.
3 2 GND
Analog Ground. Connect to the exposed paddle and analog ground plane and then connect to
PGND at the output ground.
43SS
Soft-Start Programming Input. Connect a capacitor from SS to GND to set the soft-start time.
See the Selecting the Soft-Start Capacitor section for details.
54FB
Feedback Input. Connect to the center tap of an external resistor-divider to set the output
voltage. Regulates to 0.6V for the MAX8598/MAX8599 and MAX8597 when REFIN is connected
to AVL. Regulates to V
REFIN
(MAX8597) when using an external reference.
65
COMP
Compensation Input. Connect to the required compensation network. See the Compensation
Design section for details.
7 6 EN Enable Input. Drive EN high to enable the IC. Drive low to shut down the IC.
8—
REFOUT
Internal Reference Output. REFOUT regulates to 2.5V and can source up to 1mA. REFOUT
discharges to GND during UVLO.
97V+
Input Supply Voltage for Internal VL Regulator. Connect to an input supply in the 4.5V to 28V
range. Bypass to GND with a 1µF or larger ceramic capacitor through a 3Ω resistor.
10 8 VL
Internal 5V Linear-Regulator Output. VL provides power for the internal MOSFET gate drivers.
Bypass to PGND with a 1µF or larger ceramic capacitor. VL is always enabled except in
thermal shutdown. See the Internal 5V Linear Regulator section for details.
11 9 DL
Low-Side Gate-Driver Output. Connect to the gate of the synchronous rectifier. DL swings from
PGND to VL. DL is held low during shutdown.
12 10
PGND
Power Ground. Connect to the synchronous rectifier’s source and PGND plane.
13 11 BST
Bootstrap Input Supply for the High-Side MOSFET Driver. Connect to the cathode of an external
diode from VL and connect a 0.1µF or larger capacitor from BST to LX.
14 12 DH
High-Side Gate-Driver Output. Connect to the gate of the high-side MOSFET. DH swings from
LX to BST. DH is low (connected to LX) during shutdown.
15 13 LX
External Inductor Connection. LX is the low supply for the DH gate driver as well as the sense
connection for the current-limit circuitry. Connect LX to the switched side of the inductor as well
as the source of the high-side MOSFET and the drain of the synchronous rectifier.
16 14 ILIM
Current-Limit Sense Input. Connect a resistor from ILIM to the current-sense point to set the
output current limit. See the Setting the Current Limit section for details.