Owner manual

MAX5099
Dual, 2.2MHz, Automotive Synchronous Buck
Converter with 80V Load-Dump Protection
12 ______________________________________________________________________________________
Pin Description (continued)
PIN NAME FUNCTION
15 SGND
Signal Ground. Connect SGND to exposed pad and to the board signal ground plane. Connect the board
signal ground and power ground planes together at a single point.
16 BYPASS Reference Output Bypass Connection. Bypass to SGND with a 0.22μF or greater ceramic capacitor.
17 FSEL_1
Converter 1 Frequency Select Input. Connect FSEL_1 to V
L
for normal operation. Connect FSEL_1 to SGND
to reduce converter 1’s switching frequency to 1/2 of converter 2’s switching frequency (converter 1
switching frequency is 1/4 the SYNC frequency). Do not leave FSEL_1 unconnected.
18 COMP1 Converter 1 Internal Transconductance Amplifier Output. See the Compensation section.
19 FB1
Converter 1 Feedback Input. Connect FB1 to a resistive divider between converter 1’s output and SGND to
adjust the output voltage. To set the output voltage below 0.8V, connect FB1 to a resistive voltage-divider
from BYPASS to regulator 1’s output (Figure 2). See the Setting the Output Voltage section.
20 EN1 Converter 1 Active-High Enable Input. Connect to V
L
for an always-on operation.
21 PGOOD1
Converter 1 Power-Good Output. Open-drain output goes low when converter 1’s output falls below 92.5%
of its set regulation voltage. Use PGOOD1 and EN2 to sequence the converters (converter 1 starts first).
22, 23 DRAIN1
Converter 1 Internal MOSFET Drain Connection. For buck converter operation, use the MOSFET as a high-
side switch and connect DRAIN1 to the DC-DC converters supply input rail. For boost converter operation,
use the MOSFET as a low-side switch and connect DRAIN1 to the inductor and diode junction (Figure 5).
24, 25 SOURCE1
Converter 1 Internal MOSFET Source Connection. For buck operation, connect SOURCE1 to the switched
side of the inductor. For boost operation, connect SOURCE1 to PGND (Figure 5).
26 BST1/VDD1
Converter 1 Bootstrap Flying-Capacitor Connection. For buck converter operation, connect BST1/VDD1 to a
0.1μF ceramic capacitor and diode according to the Typical Application Circuit. For boost converter
operation, driver bypass capacitor connection. Connect to VDRV and bypass with a 0.1μF ceramic
capacitor to PGND (Figure 5).
27 VDRV
Low-Side Driver Supply Input. Connect VDRV to VL through an RC filter to bypass switching noise to the
internal VL regulator. For buck converter operation, connect anode terminals of external bootstrap diodes to
VDRV. For boost converter operation, connect VDRV to BST1/VDD1 and BST2/VDD2.
Bypass with a minimum 2.2μF ceramic capacitor to PGND (see the Typical Application Circuit). Do not
connect to an external supply.
28 DL1 Converter 1 Low-Side Synchronous-Rectifier Gate Driver Output
29 PGND Power Ground. Connect to the board power ground plane.
30 DL2 Converter 2 Low-Side Synchronous-Rectifier Gate Driver Output
31 BST2/VDD2
Converter 2 Bootstrap Flying-Capacitor Connection. For buck converter operation, connect BST2/VDD2 to a
0.1μF ceramic capacitor and diode according to the Typical Application Circuit. For boost converter
operation, driver bypass capacitor connection. Connect to VDRV and bypass with a 0.1μF ceramic
capacitor from BST2/VDD2 to PGND (Figure 5).
—EP
Exposed Pad. Connect EP to SGND. For enhanced thermal dissipation, connect EP to a copper area as
large as possible. Do not use EP as the sole ground connection.