BD9528AMUV Datasheet, PDF (12/30 Pages) Rohm – High Performance Regulators for PCs Main Power Supply for Notebook PCs(With Built-in Linear Regulator)

BD9528AMUV
Technical Note
●Pin Descriptions
・VIN (30 pin)
This is the main power supply pin. The input supply voltage range is 5.5V to 28V. The duty cycle of BD9528AMUV is
determined by input voltage and control output voltage. Therefore, when VIN voltage fluctuated, the output voltage also
becomes unstable. Since VIN line is also the input voltage of switching regulator, stability depends on the impedance of
the voltage supply. It is recommended to establish bypass capacitor and CR filter suitable for the actual application.
・CTL (9 pin)
When CTL pin voltage is at least 2.3V, the status of the linear regulator output becomes active (REG1=5V, REG2=3.3V).
Conversely, the status switches off when CTL pin voltage goes lower than 0.8V. The switching regulator doesn’t become
active when the status of CTL pin is low, if the status of EN pin is high.
(※CTL pin is connected to VIN pin with 1MΩ resistor(pull up) intermall IC)
・EN1, 2 (21 pin, 4 pin)
When EN pin voltage is at least 2.3V, the status of the switching regulator becomes active. Conversely, the status switches
off when EN pin voltage goes lower than 0.8V.
(※EN pin is connected to AGND pin with 1MΩ resistor(pull down) intermall IC)
・REG1 (29 pin)
This is the output pin for 5V linear regulator and also active in power supply for driver and control circuit of the inside. The
standby function for REG1 is determined by CTL pin. The voltage is 5V, with 100mA current ability. It is recommended that
a 10μF capacitor (X5R or X7R) be established between REG1 and GND.
・REG2 (28 pin)
This is the output pin for 3.3V linear regulator. The standby function for REG2 is determined by CTL. The voltage is 3.3V,
with 100mA current ability. It is recommended that a 10μF capacitor (X5R or X7R) be established between REG2 and
GND.
・REF (12 pin)
This is the setting pin for output voltage of switching regulator. This IC controls the voltage in the status of REF≒FB.
・FB 1, 2 (14 pin, 11 pin)
This is the feedback pin from the output of switching regulator. This IC controls the voltage in the status of REF≒FB.
・Vo1 (27 pin)
This is the output discharge pin, and output voltage feedback pin for frequency setting. When the voltage is beyond 4.4V
from the external power supply during operation, it supplies REG1.
・Vo2 (7 pin)
This is the output discharge pin, and output voltage feedback pin for frequency setting.
・SS1, 2 (19 pin, 6 pin)
This is the setting pin for soft start. The rising time is determined by the capacitor connected between SS and GND, and
the fixed current inside IC after it is the status of low in standby mode. It controls the output voltage till SS voltage catch up
the REF pin to become the SS terminal voltage.
・FS1, 2 (15 pin, 10 pin)
This is the input pin for setting the frequency. It is available to set it in frequency range is 150kHz to 500kHz.
・ILIM1, 2 (17 pin, 8 pin)
BD9528AMUV detects voltage differential between SW and PGND, and set OCP. OCP setting current value is determined
by the resistance value of ILIM pin. FET of various Ron is available.
・PGOOD 1, 2 (20 pin, 5 pin)
This is the open drain pin for deciding the output of switching regulator.
・MCTL1, 2 (18 pin, 16 pin)
This is the switching shift pin for SLLM (Simple Light Load Mode). MCTL pin is at low level when it goes lower than 0.8V,
and at high level when it goes higher than 2.3V.
(※MCTL pin is connected to AGND pin with 500kΩ resistor(pull down) intermall IC)
・AGND (13 pin)
This is the ground pin.
・BOOT1, 2 (22 pin, 3 pin)
This is the power supply pin for high side FET driver. The maximum voltage range to GND pin is to 35V, to SW pin is to 7V.
In switching operations, the voltage swings from (VIN+REG1) to REG1 by BOOT pin operation.
・HG1, 2 (23 pin, 2 pin)
This is the highside FET gate drive pin. It is operated in switching between BOOT to SW. In case the output MOS is 3ohm
/the status of Hi, 2ohm/the status of Low, it is operated hi-side FET gate in high speed.
・SW1, 2 (24 pin, 1 pin)
This is the ground pin for high side FET drive. The maximum voltage range to GND pin is to 30V. Switching operation
swings from the status of BOOT to the status of GND.
・LG1, 2 (26 pin, 31 pin)
This is the lowside FET gate drive pin. It is operated in switching between REG1 to PGND. In case the output MOS is
2ohm /the status of Hi, 0.5ohm/the status of Low, it is operated low-side FET gate in high speed.
・PGND1, 2 (25 pin, 32 pin)
This is the ground pin for low side FET drive.
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2011.11 - Rev.A