X80000 Datasheet, PDF (16/37 Pages) Intersil Corporation – Smart Power Plug Penta-Power Sequence Controller with Hot Swap

X80000, X80001
Pin Descriptions (Continued)
PIN
NAME
DESCRIPTION
20
V1GOOD V1 Voltage Good Output (Active Low).This open drain output goes LOW when EN1 is less than V_TRIP1 and goes
HIGH when EN1 is greater than V_TRIP1. There is a user selectable delay circuitry on this pin.
21
RESET
RESET Output. This open drain pin is an active LOW output. This pin will be active until PWRGD goes active and
the power sequencing is complete. This pin will be released after a programmable delay.
22
WP
Write Protect. Input Pin. WP HIGH (in conjunction with WPEN bit=1) prevents writes to any memory
location in the device. It has an internal pulldown resistor. (>10MΩ typical)
23
MRC
Manual Reset Input Cold-side. Pulling the MRC pin HIGH initiates a system side RESET. The MRC signal must
be held HIGH for 5µsecs. It has an internal pulldown resistor. (>10MΩ typical)
24
NC
No Connect. No internal connections.
25
V_EE
Negative Supply Voltage Input.
26
NC
No Connect. No internal connections.
27
FAR
Failure After Re-try (FAR) output signal. Failure After Re-try (FAR) is asserted after a number of retries. Used for
Overcurrent and hardshort detection.
28
BATT-ON Battery On Input. This input signals that the battery backup (or secondary supply) is supplying power to the
backplane. It has an internal pulldown resistor. (>10MΩ typical)
29
PWRGD Power Good Output. This output pin enables a power module.
30
IGQ1
Gate Current Quick Select Bit 1 Input. This pin is used to change the gate current drive and is intended to allow
for current ramp rate control of the gate pin of an external FET. It has an internal pulldown resistor. (>10MΩ typical)
31
IGQ0
Gate Current Quick Select Bit 0 Input. This pin is used to change the gate current drive and is intended to allow
for current ramp rate control of the gate pin of an external FET. It has an internal pulldown resistor. (>10MΩ typical)
32
MRH
Manual Reset Input Hot-side. Pulling the MRH pin LOW initiates a GATE pin reset (GATE pin pulled LOW). The
MRH signal must be held LOW for 5µsecs (minimum).
Functional Description
Hot Circuit Insertion
When circuit boards are inserted into a live backplane, the
bypass capacitors at the input of the board’s power module
or DC/DC converter can draw huge transient currents as
they charge up (See Figure 22). This transient current can
cause permanent damage to the board’s components and
cause transients on the system power supply.
The X80000 is designed to turn on a board’s supply voltage
in a controlled manner (see Figure 23), allowing the board to
be safely inserted or removed from a live backplane. The
device also provides undervoltage, overvoltage and
overcurrent protection while keeping the power module (DC-
DC converter) off until the backplane input voltage is stable
and within tolerance.
I_INRUSH
-48V
Return
R5
30k
1%
R4
182K
1%
R6
10K
1%
-48V
UV=37V
V_UV/OV
OV=71V
V_DD
X80000
X80001
DC/DC
Converter
V_{EE SENSE GATE} DRAIN
Rs
0.02Ω
5%
I_inrush
0.1µF
4.7K
100
3.3n
Q1 _IRFR120
100K
DC/DC
Converter
-48V
FIGURE 22. TYPICAL -48V HOTSWAP APPLICATION CIRCUIT
V_GATE
V_{FET_DRAIN}
PWRGD
FIGURE 23. TYPICAL INRUSH WITH GATE SLEW RATE
CONTROL
16
FN8148.0
March 18, 2005