zl2005 Intersil Corporation, zl2005 Datasheet - Page 29

• Manufacturer Part Number: zl2005
• Description: Digital-dc? Integrated Power Management And Conversion Ic
• Manufacturer: Intersil Corporation

6
6.1 Input Undervoltage Lockout (UVLO)
The input undervoltage lockout (UVLO) prevents the
ZL2005 from operating when the input falls below a
preset threshold, indicating the input supply is out of
its specified range. The UVLO threshold (V
can be set between 2.85 V and 16 V using the UVLO
pin. The simplest implementation is to connect the
UVLO pin as shown in Table 22. If the UVLO pin is
left unconnected, the UVLO threshold will default to
4.5 V.
Table 22. UVLO Threshold Settings
If the desired UVLO threshold is not one of the listed
choices, the user can configure a threshold between
2.85 V and 16 V by connecting a resistor between the
UVLO pin and GND by selecting the appropriate
resistor from Table 23.
Table 23. UVLO Resistor Values
V
and 16 V via I
Once an input undervoltage fault condition occurs, the
device can respond in a number of ways as follows:
1. Continue operating without interruption.
2. Continue operating for a given delay time, fol-
UVLO
2.85 V
3.14 V
3.44 V
3.79 V
4.18 V
4.59 V
5.06 V
5.57 V
6.13 V
6.75 V
UVLO
lowed by shutdown if the fault still persists at the
Pin Setting
Power Management Functional Description
OPEN
HIGH
can also be set to any value between 2.85 V
LOW
17.8 kΩ
19.6 kΩ
21.5 kΩ
23.7 kΩ
26.1 kΩ
28.7 kΩ
31.6 kΩ
34.8 kΩ
38.3 kΩ
42.2 kΩ
2
R
C/SMBus.
UVLO
29
UVLO Threshold
14.54 V
7.42 V
8.18 V
8.99 V
10.9 V
13.2 V
UVLO
9.9 V
12 V
16 V
10.8 V
4.5 V
3 V
46.4 kΩ
51.1 kΩ
56.2 kΩ
61.9 kΩ
68.1 kΩ
82.5 kΩ
90.9 kΩ
100 kΩ
R
75 kΩ
UVLO
UVLO
)
ZL2005
3. Initiate an immediate shutdown until the fault has
The default response from a UVLO fault is an imme-
diate shutdown of the device. The device will continu-
ously check for the presence of the fault condition. If
the fault condition is no longer present, the ZL2005
will be re-enabled.
Please refer to Application Note AN13 for details on
how to configure the UVLO threshold or to select spe-
cific UVLO fault response options via the I
interface.
6.2 Output Overvoltage Protection
The ZL2005 offers an internal output overvoltage pro-
tection circuit that can be used to protect sensitive load
circuitry from being subjected to a voltage higher than
its prescribed limits. This feature is especially useful
in protecting expensive processors, FPGAs, and
ASICs from excessive voltages.
A hardware comparator is used to compare the actual
output voltage (seen at the VSEN pin) to a threshold
set to 15 % higher than the target output voltage by
default. If the voltage at the VSEN pin exceeds this
upper threshold level, the PG pin will de-assert. The
device can then respond in a number of ways as fol-
lows:
1. Initiate an immediate shutdown until the fault has
2. Turn off the high-side MOSFET and turn on the
The default response from an overvoltage fault is an
immediate shutdown of the device. The device will
continuously check for the presence of the fault condi-
tion. If the fault condition is no longer present, the
ZL2005 will be re-enabled.
Please refer to Application Note AN13 for details on
how to select specific overvoltage fault response
options via the I
end of the delay period. The device will remain in
shutdown until permitted to restart.
been cleared. The user can select a specific num-
ber of retry attempts.
been cleared. The user can select a specific num-
ber of retry attempts.
low-side MOSFET. The low-side MOSFET
remains ON until the device attempts a restart.
2
C/SMBus interface.
February 18, 2009
2
C/SMBus
FN6848.0