Rainbow Electronics MAX5098A - Manual (Page 12)

MAX5098A
Dual, 2.2MHz, Automotive Buck or Boost
Converter with 80V Load-Dump Protection
12 ______________________________________________________________________________________
Pin Description (continued)
PIN NAME FUNCTION
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 CKO 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 3). 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 Open-Drain Power-Good Output. PGOOD1 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 6).
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 6).
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 6).
27 VDRV
Low-Side Driver Supply Input. Connect VDRV to V L through an RC filter to bypass switching noise to the
internal V L 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 CKO
Clock Output. CKO is an output with twice the frequency of each converter (FSEL_1 = V L ) and 90° out-of-
phase with respect to converter 1. Connect CKO to the SYNC input of another MAX5098A for a four-phase
converter.
29, 30
PGND1,
PGND2
Power Ground. Connect both PGND1 and PGND2 together and to the board power ground plane.
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 6).
— 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.