LTC4259CGW Linear Technology, LTC4259CGW Datasheet - Page 8

• Manufacturer Part Number: LTC4259CGW
• Manufacturer: Linear Technology

Specifications of LTC4259CGW

• Linear Misc Type: Negative Voltage
• Operating Supply Voltage (typ): -48V
• Operating Supply Voltage (max): -57V
• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 36
• Lead Free Status / Rohs Status: Not Compliant

LTC4259
PI FU CTIO S
SHDN2 (Pin 18): Shutdown Channel 2, Active Low. See
SHDN1.
SHDN3 (Pin 19): Shutdown Channel 3, Active Low. See
SHDN1.
SHDN4 (Pin 20): Shutdown Channel 4, Active Low. See
SHDN1.
AGND (Pin 21): Analog Ground. AGND should be con-
nected to the return from the – 48V supply. AGND and
DGND should typically be tied together. However, if they
are not, AGND can be separated from DGND by no more
than 100mV.
SENSE4 (Pin 22): Channel 4 Current Sense Input. SENSE4
monitors the external MOSFET current via a 0.5 sense
resistor between SENSE4 and V
across the sense resistor exceeds the overcurrent detec-
tion threshold V
If the voltage across the sense resistor reaches the current
limit threshold V
GATE4 pin voltage is lowered to maintain constant current
in the external MOSFET. See Applications Information for
further details. If the channel is unused, the SENSE4 pin
must be tied to V
GATE4 (Pin 23): Channel 4 Gate Drive. GATE4 should be
connected to the gate of the external channel 4 MOSFET.
When the MOSFET is turned on, a 50 A pull-up current
source is connected to the pin. The gate voltage is clamped
to 13V (typ) above V
the voltage at GATE4 will be reduced to maintain constant
current through the external MOSFET. If the fault timer
expires, GATE4 is pulled down with 50 A, turning the
MOSFET off and recording a t
channel is unused, float the GATE4 pin or tie it to V
OUT4 (Pin 24): Channel 4 Output Voltage Monitor. OUT4
should be connected to the output port through a 10k
series resistor. A current limit foldback circuit limits the
power dissipation in the external MOSFET by reducing the
current limit threshold when the output voltage is within
18V of AGND. The port 4 Power Good bit is set when the
voltage from OUT4 to V
resistor is connected internally from OUT4 to AGND. If the
8
U
U
CUT
LIM
EE
, the current limit fault timer counts up.
.
U
EE
(typically 25mV/50mA higher), the
. During a current limit condition,
EE
drops below 2V (typ). A 2.5M
ICUT
EE
. Whenever the voltage
or t
START
event. If the
EE
.
channel is unused, the OUT4 pin can be tied to AGND or
allowed to float.
SENSE3 (Pin 25): Channel 3 Current Sense Input. See
SENSE4.
GATE3 (Pin 26): Channel 3 Gate Drive. See GATE4.
OUT3 (Pin 27): Channel 3 Output Voltage Monitor. See
OUT4.
V
– 57V supply, relative to AGND.
SENSE2 (Pin 29): Channel 2 Current Sense Input. See
SENSE4.
GATE2 (Pin 30): Channel 2 Gate Drive. See GATE4.
OUT2 (Pin 31): Channel 2 Output Voltage Monitor. See
OUT4.
SENSE1 (Pin 32): Channel 1 Current Sense Input. See
SENSE4.
GATE1 (Pin 33): Channel 1 Gate Drive. See GATE 4.
OUT1 (Pin 34): Channel 1 Output Voltage Monitor. See
OUT4.
AUTO (Pin 35): Auto Mode Input. Auto mode is intended
to allow the LTC4259 to detect and power up a PD even if
there is no host controller present on the I
this pin is high, all Mode bits in the Operating Mode
register will be set at power-up or after a system reset.
When this pin is low, all Mode bits will be cleared at
power-up or after a system reset. The states of the Mode
bits can be subsequently changed via the I
desired. The real-time state of the AUTO pin can be read
at bit 0 in the Pin Status register (11h). An internal 50k
resistor pulls AUTO low if it is left floating.
OSCIN (Pin 36): Oscillator Input. Connect to an oscillating
signal source, preferably a sine wave, of approximately
100Hz with 2V peak-to-peak amplitude, negative peaks
above – 0.3V and positive peaks below 2.5V. When a
channel is powered and AC disconnect is enabled, this
signal is used to detect the AC impedance of the PD.
EE
(Pin 28): – 48V Supply Input. Connect to a – 45.5V to
2
2
C bus. When
C interface if
4259i