MAX8664
Low-Cost, Dual-Output, Step-Down
Controller with Fast Transient Response
6 _______________________________________________________________________________________
Pin Description
PIN NAME FUNCTION
1 DH1
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.
2 LX1
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.
3 BST1
Boost Capacitor Connection for the High-Side MOSFET Driver for Controller 1. Connect a 0.22µF ceramic
capacitor from BST1 to LX1.
4 DL1
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.
5VL
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
CC
supply. Do not
load VL when IC is disabled.
6 PGND
Power Ground. Connect to the power ground plane. Connect power and analog grounds at a single point near
the output capacitor’s ground.
7 DL2
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.
8 BST2
Boost Capacitor Connection for the High-Side MOSFET Driver for Controller 2. Connect a 0.22µF ceramic
capacitor from BST2 to LX2.
9 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.
10 DH2
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.
11 ILIM2
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.
12 FB2
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
FB2
regulates to V
REFIN2
or the internal 0.6V
reference. To use the internal reference, connect REFIN2 to V
CC
.
13 REFIN2
External Reference Input for Controller 2. To use the internal 0.6V reference, connect REFIN2 to V
CC
. To use
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.
14 OSC/EN12
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.
15 IN
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.
16 GND
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.
