rt9238 ETC-unknow, rt9238 Datasheet - Page 9

• Manufacturer Part Number: rt9238
• Description: Vrm 8.5 Pwm And Triple Linear Power System Controller
• Manufacturer: ETC-unknow

Functional Pin Description
DRIVE2 (Pin 1)
Connect this pin to the gate of an external MOSEFT.
This pin provides the drive for the VTT (V
regulator’s pass transistor.
FIX (Pin 2)
Grounding this pin bypasses the internal resistor
dividers that set the voltage of the 1.5V and 1.8V
linear regulators. This way, the output voltage of the
two regulators can be adjusted from 1.26V up to the
input voltage (+3.3V or +5V) by way of an external
resistor divider corrected at the corresponding VSEN
pin. The new output voltage set by the external
resistor divider can be determined using the following
formula:
V
Where R
the output of the regulator, and R
connected from VSEN to ground. Left open, this pin
is pulled high enabling fixed output voltage operation.
VID25, VID0, VID1, VID2, VID3 (Pin 7, 6, 5, 4, and 3)
VID3-25 are TTL-compatible the input pins to the 5-
bit DAC. The state logic of these five pins program
the internal voltage reference, DACOUT. The level of
DACOUT sets the microprocessor core converter
output voltage, as well as the corresponding PGOOD
and OVP thresholds. Table 1 specifies the DACOUT
voltage of 32 combinations of VID levels.
PGOOD (Pin 8)
PGOOD is an open collector output used to indicate
the status of the PWM converter output voltage. This
pin is pulled low when the synchronous regulator
output is not within ±10% of the DACOUT reference
voltage, or when any of the other outputs are below
their under-voltage thresholds.
VTTPG (Pin 9)
VTTPG is an open collector output used to indicate
the status of the VTT (V
voltage. This pin is pulled low when the output
voltage is below 1.08V under-voltage threshold or
DS9238-01 July 2001
OUT
= 1.265V x (1+
OUT
is the resistor connected from VSEN to
R
R
OUT
GND
OUT2 )
)
GND
regulator output
is the resistor
OUT2
Preliminary
)
when SS13 pin is below 1.25V.
FAULT/VID4 (Pin 10)
This pin provides two combined functions. One is
fault condition indicator, the other is VID4 for
VRM8.4 DAC (see the Table I). Pull up this pin up to
over 2V, it act like the VID4 of VRM8.4. When this
pin
1.890V~2.090V output voltages.
Nominally, the voltage at this pin is pulled low by a
internal 47kΩ, in the event of an over-voltage or
over-current condition, this pin is internally pulled to
about 8V (VCC = 12V).
VSEN2 (Pin 11)
Connect this pin to the output of the VTT (V
linear regulator. This pin is also monitored for under-
voltage events.
SS24 (Pin 12)
Connect a capacitor from this pin to ground. This
capacitor, along with an internal 28µA (V
current source, sets the soft-start interval of the
V
a chip reset and shutdown.
SS13 (Pin 13)
Connect a capacitor from this pin to ground. This
capacitor, along with an internal 28µA (V
current source, sets the soft-start interval of the
synchronous PWM converter (V
regulator (V
delayed by the time interval required by the charging
of this capacitor from 0V to 1.25V.
VSEN4 (Pin 14)
Connect this pin to the output of the 1.8V regulator.
This pin is monitored for under-voltage events.
DRIVE4 (Pin 15)
Connect this pin to the gate of an external MOSEFT.
This pin provides the drive for the 1.8V regulator’s
pass transistor.
OUT2
is
regulator. Pulling this pin below 0.8V induces
pulled
OUT3
). A VTTPG high signal is also
high,
the
OUT1
DACOUT
www.richtek-ic.com.tw
RT9238
) and the AGP
SS24
SS13
provide
OUT2
>1V)
>1V)
9
)