MAX8686 Maxim Integrated Products, MAX8686 Datasheet - Page 9

• Manufacturer Part Number: MAX8686
• Description: DC-DC Converter Delivers Up To 25A Per Phase
• Manufacturer: Maxim Integrated Products

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DC-DC Converter Delivers Up to 25A Per Phase
PIN
33
34
35
36
37
38
39
40
—
—
—
P H AS E /RE FO
GND_EP
NAME
COMP
LX_EP
REFIN
FREQ
IN_EP
ILIM
RS+
RS-
SS
_______________________________________________________________________________________
Frequency-Setting Input. Connect a capacitor from FREQ to GFREQ to set the switching frequency.
The triangle ramp runs between 0 and AVL/2. In multiphase applications, connect FREQ of the master
and all slave devices together. FREQ is internally pulled to GFREQ during shutdown.
Soft-Start Input. For master-mode or single-phase operation, connect a capacitor from SS to GND to
set the soft-start time. A 25µA internal current source charges the capacitor. SS is pulled to GND in
shutdown. Connect SS to GND for slave mode operation.
Analog Programmable Current Limit. Connect a resistor from ILIM to GND to set the current limit. A
10µA current source through this resistor sets the current-limit threshold. In multiphase applications,
connect ILIM of the master and all slave devices together.
Voltage Error-Amplifier Reference Input. For master-mode or single-phase operation, connect REFIN to
PHASE/REFO through a resistor-divider to set the output voltage from 0 to 3.3V. To use an external
reference, connect REFIN to the system reference voltage, and use an RC network at REFIN to
implement soft-start if the external reference does not provide this function. Connect REFIN to GND for
slave mode operation.
Phase Selection Input/Reference Voltage Output. For single-phase or master-mode operation, the 3.3V
output with 1% accuracy can be used as a reference voltage. For multiphase operation, connect
PHASE/REFO of each slave device to the center tap of a resistor-divider from the master AVL to GND.
The resistor values are selected to set phase delay between phases. The PWM cycle starts 60ns after
the rising edge of V
Compensation and Output of the Voltage-Error Amplifier. Connect a Type II compensation network at
COMP. COMP is internally pulled to GND in shutdown. In multiphase applications, connect COMP of
the master and all slave devices together.
Positive Input of the Output-Voltage Remote Sense. For master-mode or single-phase operation,
connect RS+ to the output-voltage sense point at the load. Connect RS+ to AVL (slave) for slave mode
operation.
Negative Input of the Output-Voltage Remote Sense. For master-mode or single-phase operation,
connect RS- to the remote ground at the load. Connect RS- to AVL (slave) for slave mode operation.
Ground Exposed Paddle. Connect GND_EP to GND.
Input Exposed Paddle. Connect IN_EP to IN.
LX Exposed Paddle. Connect LX_EP to LX.
Single/Multiphase, Step-Down,
FREQ
crosses V
PHASE
.
FUNCTION
Pin Description (continued)
9