ISL6227EVAL2Z Intersil, ISL6227EVAL2Z Datasheet - Page 10
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ISL6227EVAL2Z
Manufacturer Part Number
ISL6227EVAL2Z
Description
EVAL BOARD ISL6227
Manufacturer
Intersil
Specifications of ISL6227EVAL2Z
Main Purpose
Special Purpose DC/DC, DDR Memory Supply
Outputs And Type
2, Non-Isolated
Voltage - Output
0.9 ~ 5.5V
Voltage - Input
5 ~ 24V
Regulator Topology
Buck
Frequency - Switching
300kHz
Board Type
Fully Populated
Utilized Ic / Part
ISL6227
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Functional Pin Description
GND
Signal ground for the IC.
LGATE1, LGATE2
These are the outputs of the lower MOSFET drivers.
PGND1, PGND2
These pins provide the return connection for lower gate
drivers, and are connected to sources of the lower
MOSFETs of their respective converters.
PHASE1, PHASE2
The PHASE1 and PHASE2 points are the junction points of
the upper MOSFET sources, output filter inductors, and
lower MOSFET drains. Connect these pins to the respective
converter’s upper MOSFET source.
UGATE1, UGATE2
These pins provide the gate drive for the upper MOSFETs.
BOOT1, BOOT2
These pins power the upper MOSFET drivers of the PWM
converter. Connect this pin to the junction of the bootstrap
capacitor with the cathode of the bootstrap diode. The anode
of the bootstrap diode is connected to the VCC voltage.
ISEN1, ISEN2
These pins are used to monitor the voltage drop across the
lower MOSFET for current feedback and Overcurrent
protection. For precise current detection these inputs can be
connected to the optional current sense resistors placed in
series with the source of the lower MOSFETs.
EN1, EN2
These pins enable operation of the respective converter
when high. When both pins are low, the chip is disabled and
only low leakage current is taken from VCC and VIN. EN1
and EN2 can be used independently to enable either
Channel 1 or Channel 2.
VOUT1, VOUT2
These pins, when connected to the converter’s respective
outputs, set the converter operating in a mixed hysteretic
mode or PWM mode, depending on the load conditions. It
also provides the voltage to the chip to clamp the PWM error
amplifier in hysteretic mode to achieve smooth HYS/PWM
transition. When connected to ground, these pins command
forced continuous conduction mode (PWM) at all load levels.
VSEN1, VSEN2
These pins are connected to the resistive dividers that set
the desired output voltage. The PGOOD, UVP, and OVP
circuits use this signal to report output voltage status.
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ISL6227
OCSET1
This pin is a buffered 0.9V internal reference voltage. A
resistor from this pin to ground sets the overcurrent
threshold for the first controller.
SOFT1, SOFT2
These pins provide soft-start function for their respective
controllers. When the chip is enabled, the regulated 4.5µA
pull-up current source charges the capacitor connected from
the pin to ground. The output voltage of the converter follows
the ramping voltage on the SOFT pin in the soft-start
process with the SOFT pin voltage as reference. When the
SOFT pin voltage is higher than 0.9V, the error amplifier will
use the internal 0.9V reference to regulate output voltage.
In the event of undervoltage and overcurrent shutdown, the
soft-start pin is pulled down though a 2k resistor to ground to
discharge the soft-start capacitor.
DDR
When the DDR pin is low, the chip can be used as a dual
switcher controller. The output voltage of the two channels
can be programmed independently by VSENx pin resistor
dividers. The PWM signals of Channel 1 and Channel 2 will
be synchronized 180° out-of-phase. When the DDR pin is
high, the chip transforms into a complete DDR memory
solution. The OCSET2 pin becomes an input through a
resistor divider tracking to VDDQ/2. The PG2/REF pin
becomes the output of the VDDQ/2 buffered voltage. The
VDDQ/2 voltage is also used as the reference to the error
amplifier by the second channel. The channel phase-shift
synchronization is determined by the VIN pin when DDR = 1
as described in VIN below.
VIN
This pin has multiple functions. When connected to battery
voltage, it provides battery voltage to the oscillator as a
feed-forward for the rejection of input voltage variation. The
ramp of the PWM comparator is proportional to the voltage
on this pin (see Table 1 and Table 2 for details). While the
DDR pin is high in the DDR application, and when the VIN
pin voltage is greater than 4.2V when connecting to a
battery, it commands 90° out-of-phase channel
synchronization, with the second channel lagging the first
channel, to reduce inter-channel interference. When the pin
voltage is less than 4.2V, this pin commands in-phase
channel synchronization.
PG1
PGOOD1 is an open drain output used to indicate the status
of the output voltage. This pin is pulled low when the first
channel output is out of -11% to +15% of the set value.
May 4, 2009
FN9094.7