LM5067EVAL National Semiconductor, LM5067EVAL Datasheet - Page 19

• Manufacturer Part Number: LM5067EVAL
• Description: NEGATIVE HOT SWAP / INRUSH CURRE
• Manufacturer: National Semiconductor

Specifications of LM5067EVAL

• Main Purpose: Power Management, Hot Swap Controller
• Utilized Ic / Part: LM5067
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -

As an example, assume the application requires the following
thresholds: V
V
resistor values are:
R1 = 227 kΩ, R2 = 39.1 kΩ
R3 = 90.9 kΩ, R4 = 3.95 kΩ
Where the R1-R4 resistor values are known, the threshold
voltages and hysteresis are calculated from the following:
Note: Ensure the voltages at the UVLO and OVLO pins do
not exceed the Absolute Maximum ratings for those pins
when the system voltage is at maximum.
Option C: The minimum UVLO level is obtained by connect-
ing the UVLO pin to VCC as shown in Figure 13. Q1 is
switched on when the operating voltage reaches the POR
threshold (
R4 using the procedure in Option B.
Note: Ensure the voltage at the OVLO pin does not ex-
ceed the Absolute Maximum ratings for that pin when the
system voltage is at maximum.
OVL
= -58V. Therefore V
≊
8.4V). The OVLO thresholds are set by R3 and
UVH
= -22V, V
UV(HYS)
UVL
= 5V, and V
= -17V, V
OVH
OV(HYS)
= -60V, and
= 2V. The
EN
19
Option D: The OVLO function can be disabled by connecting
the OVLO pin to VEE. The UVLO thresholds are set as de-
scribed in Option B or Option C.
SHUTDOWN / ENABLE CONTROL
Figure 14a shows how to use the UVLO/EN pin for remote
shutdown and enable control. Taking the UVLO/EN pin below
its 2.5V threshold (with respect to VEE) shuts off the load
current. Upon releasing the UVLO/EN pin the LM5067 switch-
es on the load current with in-rush current and power limiting.
In Figure 14b the OVLO pin is used for remote shutdown and
enable control. When the external transistor is off, the OVLO
pin is above its 2.5V threshold (with respect to VEE) and the
load current is shut off. Turning on the external transistor al-
lows the LM5067 to switch on the load current with in-rush
current and power limiting.
a) Shutdown/Enable Using the UVLO/EN Pin
b) Shutdown/Enable Using the OVLO Pin
FIGURE 14. Shutdown/Enable
FIGURE 13. UVLO = POR
EN
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