Miele T 9246 C Specifications download pdf (Page 14)

10 kW

Vin

FCX491A

UC9246

ToPowerStage

+3.3V

+1.8V

0.1 Fm

4.7 Fm

V33FB

V33A

V33D

BPCap

0.1 Fm

UCD9246

SLVSA34 –JANUARY 2010

www.ti.com

Some circuits in the device require 1.8V that is generated internally from the 3.3V supply. This voltage requires a

0.1 µF to 1 µF bypass capacitor from BPCap to ground.

Figure 6. 3.3V Shunt Regulator Controller I/O

Power On Reset

The UCD9246 has an integrated power-on reset (POR) circuit that monitors the supply voltage. At power-up, the

POR circuit detects the V33D rise. When V33D is greater than V

RESET

, the device initiates an internal startup

sequence. At the end of the delay sequence, the device begins normal operation, as defined by the downloaded

device PMBus configuration.

External Reset

The device can be forced into the reset state by an external circuit connected to the nRESET pin. A logic low

voltage on this pin holds the device in reset. To avoid an erroneous trigger caused by noise, a 10 kΩ pull up

resistor to 3.3V is recommended.

Output Voltage Adjustment

The nominal output voltage is programmed by a combination of PMBus commands: VOUT_COMMAND,

VOUT_CAL_OFFSET, VOUT_SCALE_LOOP, and VOUT_MAX. Their relationship is shown in Figure 7. These

PMBus parameters need to be set such that the resulting Vref DAC value does not exceed the maximum value

of V

ref

Output voltage margining is configured by the VOUT_MARGIN_HIGH and VOUT_MARGIN_LOW commands.

The OPERATION command selects between the nominal output voltage and either of the margin voltages. The

OPERATION command also includes an option to suppress certain voltage faults and warnings while operating

at the margin settings.

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Miele T 9246 C Specifications Page 14