MAX8553 데이터 시트보기 (PDF) - Maxim Integrated
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MAX8553 Datasheet PDF : 24 Pages
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4.5V to 28V Input, Synchronous PWM Buck Controllers
for DDR Termination and Point-of-Load Applications
Pin Description
PIN MAX8553 MAX8554
FUNCTION
EN/HSD
1
Enable/High-Side Drain. Connect to the high-side N-channel MOSFET drain through a 5.1kΩ
—
resistor for normal operation. Connect to GND for low-power shutdown (Figure 2). If the enable
function is not used, connect EN/HSD directly to the high-side N-channel MOSFET drain.
—
HSD High-Side Drain. Connect to the high-side N-channel MOSFET drain for normal operation.
REFIN
2
—
—
Reference Input. An applied voltage at REFIN sets VVTT and VVTTR to 1/2 VREFIN. REFIN voltage
range is from 0 to +3.6V.
EN
Enable. Drive EN high to enable the output. Drive EN low to shut down the IC. If the enable
function is not used, connect EN to V+.
3
POK
POK
Power-OK Output. POK is an open-drain output and is logic high when both VTT and VTTR are
within 12% of regulation. POK is pulled low in shutdown.
VTT
—
VTT Feedback Input. Connect to VTT output.
4
—
FB
Output Feedback. Connect to the center of a resistor-divider between the output and ground to
set the output voltage. FB threshold is 0.6V.
5
ILIM
ILIM
Current-Limit Threshold Adjustment. Connect a resistor from ILIM to GND to set the current-limit
threshold, or connect ILIM to VL for the default setting. See the Setting the Current Limit section.
6
FSEL
FSEL Frequency Select. Selects the switching frequency. See Tables 1 and 2 for configuration of
FSEL.
7
REF
REF Reference. Connect a 0.22µF or greater capacitor from REF to GND.
8
GND
GND Ground
VTTR
9
—
—
OUT
VTTR Reference Output. Connect a 1µF or greater capacitor from VTTR to GND. VTTR is
capable of sourcing and sinking up to 25mA.
Output Voltage. Connect directly to the output. OUT senses the output voltage to determine the
on-time for the high-side switching MOSFET.
10
V+
V+
Input Supply Voltage. Supply input for the VL regulator. Bypass with a 0.22µF or greater
capacitor.
11
VL
VL
Internal Regulator Output. Connect a 2.2µF or greater capacitor from VL to GND. VL can be
connected to V+ if the operating range is from +4.5V to +5.5V.
12
DL
DL
Low-Side MOSFET Gate Drive. Connect to the gate of the low-side N-channel MOSFET. DL is
low in shutdown or in undervoltage lockout.
13
PGND
PGND Power Ground
14
BST
BST
Bootstrapped Supply. Drives high-side N-channel MOSFET. Connect a 0.1µF or greater
capacitor from BST to LX.
15
DH
16
LX
DH
High-Side MOSFET Gate Drive. Connect to the high-side N-channel MOSFET gate. DH is low in
shutdown or in undervoltage lockout.
LX
Inductor Switching Node
______________________________________________________________________________________ 11
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