MAX8664 Maxim Integrated Products, MAX8664 Datasheet - Page 6

• Manufacturer Part Number: MAX8664
• Description: Step-Down Controller
• Manufacturer: Maxim Integrated Products

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Low-Cost, Dual-Output, Step-Down
Controller with Fast Transient Response
6
PIN
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
_______________________________________________________________________________________
OSC/EN12
REFIN2
NAME
PGND
ILIM2
BST1
BST2
GND
DH1
DH2
LX1
DL1
DL2
LX2
FB2
VL
IN
High-Side MOSFET Driver Output for Controller 1. Connect DH1 to the gate of the high-side MOSFET. DH1 is
low in shutdown and UVLO.
External Inductor Connection for Controller 1. Connect LX1 to the switching node of the MOSFETs and
inductor. Make sure LX1 is close to the source of the high-side MOSFET(s) to form a Kelvin connection for
high-side current sensing. LX1 is high impedance during monotonic startup and shutdown.
Boost Capacitor Connection for the High-Side MOSFET Driver for Controller 1. Connect a 0.22µF ceramic
capacitor from BST1 to LX1.
Low-Side MOSFET Driver Output for Controller 1. Connect DL1 to the gate of the low-side MOSFET(s) for
controller 1. DL1 is low in shutdown and UVLO.
Low-Side Gate Drive Supply and Output of the 6.5V Linear Regulator. Connect a 4.7µF ceramic capacitor from
VL to PGND. When using a 4.5V to 5.5V supply, connect VL to IN. VL is the input to the V
load VL when IC is disabled.
Power Ground. Connect to the power ground plane. Connect power and analog grounds at a single point near
the output capacitor’s ground.
Low-Side MOSFET Driver Output for Controller 2. Connect DL2 to the gate of the low-side MOSFET(s) for
controller 2. DL2 is low in shutdown and UVLO.
Boost Capacitor Connection for the High-Side MOSFET Driver for Controller 2. Connect a 0.22µF ceramic
capacitor from BST2 to LX2.
External Inductor Connection for Controller 2. Connect LX2 to the switching node of the MOSFETs and
inductor. Make sure LX2 is close to the source of the high-side MOSFET(s) to form a Kelvin connection for
high-side current sensing. LX2 is high impedance during monotonic startup and shutdown.
High-Side MOSFET Driver Output for Controller 2. Connect DH2 to the gate of the high-side MOSFET(s) for
controller 2. DH2 is low in shutdown and UVLO.
Current-Limit Set for Controller 2. Connect a resistor from the drain of the high-side MOSFET(s) to ILIM2. See
the Setting the Overcurrent Threshold section.
Feedback Input for Controller 2. Connect FB2 to the center of a resistor-divider connected between the output
of controller 2 and GND to set the desired output voltage. V
reference. To use the internal reference, connect REFIN2 to V
External Reference Input for Controller 2. To use the internal 0.6V reference, connect REFIN2 to V
an external reference, connect REFIN2 through a resistor (> 1kΩ) to a reference voltage between 0V and
1.3V. An RC lowpass filter is recommended when using an external reference and soft-start is not provided by
the external reference. For tracking applications, connect REFIN2 to the center of a resistor voltage-divider
between the output of controller 1 and GND (see Figure 3). Connect REFIN2 to GND to disable controller 2.
Switching Frequency Set Input. Connect a 22.6kΩ to 226kΩ resistor from OSC/EN12 to GND to set the
switching frequency between 1000kHz and 100kHz. Connect a switch in series with this resistor for
enable/shutdown control. When the switch is open, the IC enters low-power shutdown mode. In shutdown,
OSC/EN12 is internally driven to approximately 800mV.
Internal 6.5V Linear Regulator Input. Connect IN to a 7.2V to 28V supply, and connect a 0.47µF or larger
ceramic capacitor from IN to PGND. When using a 4.5V to 5.5V supply, connect IN to VL.
Analog Ground. Connect to the analog ground plane. Connect the analog and power ground planes at a
single point near the output capacitor’s ground.
FUNCTION
FB2
CC
regulates to V
.
REFIN2
Pin Description
or the internal 0.6V
CC
supply. Do not
CC
. To use