ISL6144_07 Datasheet, PDF (6/29 Pages) Intersil Corporation – High Voltage ORing MOSFET Controller

ISL6144
Electrical Specifications V_IN = 48V, T_A = -40°C to +105°C, Unless Otherwise Specified (Continued)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
COMP Input Current
I_COMP
-
(bias current)
HVREF Voltage (V_IN - HVREF) HV_REF(VZ) V_IN = 10V to 75V
-
VSET Voltage (V_OUT - VSET)
V_REF(VSET) V_IN = 10V to 75V
-
Fault Low Output Voltage
V_{FLT_L} V_IN - V_OUT < 0V, V_GATE = V_GL
-
Fault Sink Current
I_{FLT_SINK} FAULT = V_{FLT_L}, V_IN < V_OUT, V_GATE = V_GL
4
Fault Leakage Current
I_{FLT_LEAK} FAULT = ”V_{FLT_H}”, V_IN > V_OUT, V_GATE = V_IN + V_GQP
-
Fault Delay - Low to High
T_FLT
GATE = V_GL to FAULT ₌ V_{FLT_L}
-
NOTES:
5. The †denotes parameters which are guaranteed by design and not production tested.
6. Specifications to +105°C and -40°C are guaranteed by design and not production tested.
TYP
1.1
5.5
5.3
-
-
-
120
MAX
-
UNITS
µA
-
V
-
V
0.5
V
-
mA
10
µA
-
µs
Functional Pin Description
GATE
This is the Gate Drive output of the external N-Channel
MOSFET generated by the IC internal charge pump. Gate
turn-on time is typically 1ms.
VIN
Input bias pin connected to the sourcing supply side (ORing
MOSFET Source). Also serves as the sense pin to
determine the sourcing supply voltage. The ORing MOSFET
will be turned off when VIN becomes lower than VOUT by a
value more than the externally set threshold.
VOUT
Connected to the Load side (ORing MOSFET Drain). This is
the VOUT sense pin connected to the load. This is the
common connection point for multiple paralleled supplies.
VOUT is compared to VIN to determine when the ORing
FET has to be turned off.
HVREF
Low side of the internal IC High Voltage Reference used by
internal circuitry, also available as an external pin for
additional external capacitor connection.
COMP
This is the high side connection for the HS Comparator trip
level setting (V_TH(HS)). Resistor R₁, connected between
COMP and V_OUT along with resistor R₂, provides adjustable
V_OUT - V_IN trip level (0V to 5V). This provides flexibility to
externally set the desired level depending on particular
system requirement.
VSET
Low side connection for the HS Comparator trip level setting
A second resistor R₂ connected between VSET and COMP
provides adjustable “V_IN - V_OUT” level along with R₁.
FAULT
Open-Drain pull-down FAULT Output with internal on chip
filtering (T_FLT). The ISL6144 fault detection circuitry will pull
down this pin to GND as soon as it detects a fault. Different
types of faults and their detection mechanisms are discussed
in more detail in the Block Diagram Description section.
GND
IC ground reference.
Detailed Description
The ISL6144 and a suitably sized N-Channel power
MOSFET(s) increases power distribution efficiency and
availability when replacing a power ORing diode in high current
applications. Refer to the Application Consideration section for
power saving when using ISL6144 with an N-channel ORing
MOSFET compared to a typical ORing diode.
Functional Block Description
Regulating Amplifier-Slow (Quiet) Turn-off
A Hysteretic Regulating (HR) Amplifier is used for a
Quiet/ Slow turn-off mechanism. This slow turn-off is initiated
when the sourcing power supply is turned off slowly for
system diagnostics. Under normal operating conditions as
V_OUT pulls up to 20mV below V_IN (V_IN - 20mV > V_OUT), the
HR Amplifier regulates the gate voltage to keep the 20mV
(V_{FWD_HR}) forward voltage drop across the ORing MOSFET
(Vs - Vd). This will continue until the load current exceeds
the MOSFET ability to deliver the current with Vsd of 20mV.
In this case, Gate will be charged to the full charge pump
voltage (V_GQP) to fully enhance the MOSFET. At this point,
the MOSFET will be fully enhanced and behave as a
constant resistor valued at the r_DS(ON). Once V_IN starts to
drop below V_OUT, regulation cannot be maintained and the
output of the HR Amp is pulled high and the gate is pulled
down to V_IN slowly in less than a 100µs. As a result, the
ORing FET is turned off, avoiding reverse current as well as
voltage and current stresses on supply components.
6
FN9131.3
February 15, 2007