zl2103 Intersil Corporation, zl2103 Datasheet - Page 22

• Manufacturer Part Number: zl2103
• Description: 3a Digital-dc Synchronous Step-down Dc/dc Converter
• Manufacturer: Intersil Corporation

Output Overcurrent Protection
The ZL2103 can protect the power supply from damage if the
output is shorted to ground or if an overload condition is imposed
on the output. Once the current limit threshold has been selected
(see “Current Sensing and Current Limit Threshold Selection” on
page 19), the user may determine the desired course of action in
response to the fault condition. The following overcurrent
protection response options are available:
Thermal Overload Protection
The ZL2103 includes an on-chip thermal sensor that
continuously measures the internal temperature of the die and
will shutdown the device when the temperature exceeds the
preset limit. The factory default temperature limit is set to
+125°C, but the user may set the limit to a different value if
desired. See Application Note
setting a higher thermal limit via the I
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:
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 approximately +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. Please refer to Application Note
for details on how to select specific temperature fault response
options via I
1. Initiate a shutdown and attempt to restart an infinite number
2. Initiate a shutdown and attempt to restart a preset number of
3. Continue operating for a given delay period, followed by
4. Continue operating through the fault (this could result in
5. Initiate an immediate shutdown.
6. The default response from an overcurrent fault is an
1. Initiate a shutdown and attempt to restart an infinite number
2. Initiate a shutdown and attempt to restart a preset number of
3. Continue operating for a given delay period, followed by
4. Continue operating through the fault (this could result in
5. Initiate an immediate shutdown.
of times with a preset delay period between attempts.
times with a preset delay period between attempts.
shutdown if the fault still exists.
permanent damage to the power supply).
immediate shutdown of the device. Please refer to
Application Note
overcurrent fault response options via I
of times with a preset delay period between attempts.
times with a preset delay period between attempts.
shutdown if the fault still exists.
permanent damage to the power supply).
2
C/SMBus.
AN2033
22
for details on how to select specific
AN2033
2
C/SMBus interface may
for details. Note that
2
C/SMBus.
AN2033
ZL2103
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.
Voltage tracking protects these sensitive ICs by limiting the
differential voltage between multiple power supplies during the
power-up and power down sequence. The ZL2103 integrates a
lossless tracking scheme that allows its output to track a voltage
that is applied to the VTRK pin with no additional 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.
The ZL2103 offers two modes of tracking. Figure 18 illustrates
the output voltage waveform for the two tracking modes.
The master 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 10ms
must be configured into the master device using the SS pin, and
1. Coincident. This mode configures the ZL2103 to ramp its
2. Ratiometric. This mode configures the ZL2103 to ramp its
output voltage at the same rate as the voltage applied to the
VTRK pin.
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 may be used to configure a different tracking
ratio.
V
V
V
TRK
OUT
OUT
FIGURE 18. TRACKING MODES
ZL
V
Ratiometric
Coincident
IN
SW
V
OUT
V
V
V
V
TRK
OUT
TRK
OUT
Time
Time
May 3, 2011
FN6966.5