ZL2004 datasheet(30/42 Pages) INTERSIL

30 / 42 page

ZL2004

Data Sheet Revision 2/18/2009

www.intersil.com

6.5 Thermal Overload Protection

The ZL2004 includes an on-chip thermal sensor that

continuously measures the internal temperature of the

die and shuts down the device when the temperature

exceeds the preset limit. The default temperature limit

is set to 125°C in the factory, but the user may set the

limit to a different value if desired. See Application

Note AN33 for details. Note that setting a higher

thermal limit via the I2C/SMBus interface may result in

permanent damage to the device. Once the device has

been disabled due to an internal temperature fault, the

user may select one of several fault response options as

follows:

1. Initiate a shutdown and attempt to restart an

infinite number of times with a preset delay period

between attempts.

2. Initiate a shutdown and attempt to restart a preset

number of times with a preset delay period

between attempts.

3. Continue operating for a given delay period,

followed by shutdown if the fault still exists.

4. Continue operating through the fault (this could

result in permanent damage to the power supply).

5. Initiate an immediate shutdown.

If the user has configured the device to restart, the

device will wait the preset delay period (if configured

to do so) and will then check the device temperature. If

the temperature has dropped below a threshold that is

approx 15°C lower than the selected temperature fault

limit, the device will attempt to re-start. If the

temperature still exceeds the fault limit the device will

wait the preset delay period and retry again.

The default response from a temperature fault is an

immediate shutdown of the device. The device will

continuously check for the fault condition, and once

the fault has cleared the ZL2004 will be re-enabled.

6.6 Voltage Tracking

Numerous high performance systems place stringent

demands on the order in which the power supply

voltages are turned on. This is particularly true when

powering FPGAs, ASICs, and other advanced

processor devices that require multiple supply voltages

to power a single die. In most cases, the I/O interface

operates at a higher voltage than the core and therefore

the core supply voltage must not exceed the I/O supply

voltage according to the manufacturers' specifications.

The ZL2004 integrates a lossless tracking scheme that

allows its output to track a voltage that is applied to the

VTRK pin with no external components required. The

VTRK pin is an analog input that, when tracking mode

is enabled, configures the voltage applied to the VTRK

pin to act as a reference for the device’s output

regulation.

Figure 18 illustrates the typical connection and the two

tracking modes:

1. Coincident. This mode configures the ZL2004 to

ramp its output voltage at the same rate as the

voltage applied to the VTRK pin.

2. Ratiometric. This mode configures the ZL2004 to

ramp its output voltage at a rate that is a percentage

of the voltage applied to the VTRK pin. The

default setting is 50%, but an external resistor

string may be used to configure a different tracking

ratio.

The master ZL2004 device in a tracking group is

defined as the device that has the highest target output

voltage within the group. This master device will

control the ramp rate of all tracking devices and is not

configured for tracking mode. A delay of at least 10 ms

must be configured into the master device using the SS

pin and the user may also configure a specific ramp

rate using the SS pin.

Any device that is configured for tracking mode will

ignore its soft-start delay and ramp time settings (SS

pin) and its output will take on the turn-on/turn-off

characteristics of the reference voltage present at the

VTRK pin.

ZL2004 Datasheet(PDF) 30 Page - Intersil Corporation

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