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dc2334af

DEMO MANUAL DC2334A

HARDWARE SETUP

Turrets

E2 (GPIO) – LED2: General Purpose Input/Output. Lights

up green when pulled low. Default is input.

E3 (OVDD): Power supply for digital interface. For typi-

cal operation it is connected via J4 to a 5V supply from

a DC590/DC2026. In case the user connects another

controller board, a supply voltage between 1.8V to 5V can

be connected to this turret. For an OVDD supply < 4.8V, a

suitable voltage input must be connected to AVCC/DVCC.

See jumper JP2 (A/DVCC) or turret E5 (A/DVCC).

E4(ALERTB)–LED1:AlertOutput.PulledlowonanALERT

condition (default on start-up). Can also be monitored on

theALERTturret.LED1lightsupredifALERTBispulledlow.

E5 (A/DVCC): Analog and digital supply input. AVCC and

DVCC are shorted onboard by zero ohm resistor R9. See

JP2 for possible supply options.

E6 (SCL/SCK): Serial clock input for I2C and SPI interface.

E7 (SDO): Serial data output for I2C and SPI interface. In

I2C mode this signal is shorted to SDI by jumper JP5 to

form the SDA signal.

E8 (SDI): Serial data input for I2C and SPI interface. In

I2C mode this signal is shorted to SDO by jumper JP5 to

form the SDA signal.

E10 (CSB): Chip select input for SPI interface. In I2C mode

it is part of the slave address configuration.

E12 (VP), E13 (VM): Positive (VP) and negative (VM)

input of voltage ADC. Measurement range is 0V to 15V.

Make sure jumpers JP3 (VP) and JP4 (VM) are both set

to EXT before applying any voltage sources.

E14, E15, E16, E17, E18 (GND): Ground turrets.

POWERING THE DC2334A

The DC2334A supports many different supply options.

In the default configuration OVDD is supplied by 5V from

DC590. For this reason, JP6 (VCCIO) on the DC590 must

be set to 5V. If using a DC2026A, jumper JP1 must be

shorted (which is the default if PCB trace JP1 wasn’t cut).

For the DC2026B (and newer versions), set jumper JP3 to

5V (default). See the latest demo manual of those boards

for details. If the supply from those boards is disabled or

a user specific board is used, any voltage between 1.8V

and 5V can be connected to OVDD.

A/DVCC can be supplied by IP, externally or on-board

which is the default, see JP2. If A/DVCC and OVDD are

not supplied from the same source, make sure OVDD

reaches its minimum operating voltage of 1.8V before A/

DVCC reaches its undervoltage lockout threshold of 4.5V.

In the default setting of JP2, the power sequence timing

is inherently met.

RINGING

It comes as a surprise to many that seemingly innocent

acts, such as making a connection to a live supply, may

destroy an IC due to ringing. This ringing is an effect of

the LC oscillator that is formed by the cable inductance,

the supply decoupling capacitor and other parasitics. The

longer the cable that is used to power the board, the big-

ger its inductance and so is the energy that is stored in

it when hot-plugging. Larger inductance also means low

frequency of the LC oscillator, so the ringing lasts longer.

Under particular conditions, the ringing can reach more

than two times the input voltage and last several micro-

seconds, enough to exceed the absolute maximum ratings

of the part and destroy it. Figure 4 shows this effect when

hot-plugging A/DVCC to a 15V power supply with a 50cm

cable. The maximum amplitude is over 30V.

Figure 4. Ringing on A/DVCC when Hot-Plugging to a

15V Supply with a 50cm Cable

2µs/DIV

dc2334a F04

5V/DIV

Avoiding ringing is easily achieved by first wiring up the

board and then slowly ramping up the supplies. If OVDD

and A/DVCC are supplied separately, make sure OVDD is

turned on first.

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