Datasheet

LTC4267
3
4267fc
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. (Note 3)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
MARGIN
V
CLAMP1mA
– V
TURNON
Margin ● 0.05 0.6 V
I
VPORTN_ON
V
PORTN
Supply Current when ON V
PORTN
= –48V, P
OUT
,
⎯
P
⎯
W
⎯
R
⎯
G
⎯
D, SIGDISA Floating ● 3 mA
I
PVCC_ON
P
VCC
Supply Current (Note 7)
Normal Operation V
ITH
/RUN – PGND = 1.3V ● 240 350 µA
Start-Up P
VCC
– PGND = V
TURNON
– 100mV ● 40 90 µA
I
VPORTN_CLASS
V
PORTN
Supply Current V
PORTN
= –17.5V, P
OUT
Tied to V
PORTP
, R
CLASS
, ● 0.35 0.5 0.65 mA
During Classifi cation SIGDISA Floating (Note 8)
∆I
CLASS
Current Accuracy 10mA < I
CLASS
< 40mA, –12.5V ≤ V
PORTN
≤ –21V ● ±3.5 %
During Classifi cation (Notes 9, 10)
R
SIGNATURE
Signature Resistance –1.5V ≤ V
PORTN
≤ – 9.5V, P
OUT
Tied to V
PORTP
, ● 23.25 26.00 kΩ
IEEE 802.3af 2-Point Measurement (Notes 4, 5)
R
INVALID
Invalid Signature Resistance –1.5V ≤ V
PORTN
≤ – 9.5V, SIGDISA and P
OUT
Tied to ● 9 11.8 kΩ
V
PORTP
, IEEE 802.3af 2-Point Measurement
(Notes 4, 5)
V
IH
Signature Disable With Respect to V
PORTN
● 3 57 V
High Level Input Voltage High Level Invalidates Signature (Note 11)
V
IL
Signature Disable With Respect to V
PORTN
● 0.45 V
Low Level Input Voltage Low Level Enables Signature
R
INPUT
Signature Disable, Input Resistance With Respect to V
PORTN
● 100 kΩ
V
PG_OUT
Power Good Output Low Voltage I = 1mA V
PORTN
= –48V, ● 0.5 V
⎯
P
⎯
W
⎯
R
⎯
G
⎯
D Referenced to V
PORTN
Power Good Trip Point V
PORTN
= –48V, Voltage between V
PORTN
and P
OUT
(Note 10)
V
PG _FALL
P
OUT
Falling ● 1.3 1.5 1.7 V
V
PG_RISE
P
OUT
Rising ● 2.7 3.0 3.3 V
I
PG_LEAK
Power Good Leakage Current V
PORTN
= 0V,
⎯
P
⎯
W
⎯
R
⎯
G
⎯
D FET Off, V
⎯
P
⎯
W
⎯
R
⎯
G
⎯
D
= 57V ● 1 µA
R
ON
On-Resistance I = 300mA, V
PORTN
= –48V, Measured from 1.0 1.6 Ω
V
PORTN
to P
OUT
(Note 10) ● 2 Ω
V
ITHSHDN
Shutdown Threshold (at I
TH
/RUN) P
VCC
– PGND = V
TURNON
+ 100mV ● 0.15 0.28 0.45 V
I
THSTART
Start-Up Current Source at I
TH
/RUN V
ITH
/RUN – PGND = 0V, P
VCC
– P
GND
= 8V 0.2 0.3 0.4 µA
V
FB
Regulated Feedback Voltage Referenced to PGND, P
VCC
– P
GND
= 8V (Note 12) ● 0.780 0.800 0.812 V
I
FB
V
FB
Input Current P
VCC
– P
GND
= 8V (Note 12) 10 50 nA
g
m
Error Amplifi er Transconductance I
TH
/RUN Pin Load = ±5µA (Note 12) 200 333 500 µA/V
∆V
O(LINE)
Output Voltage Line Regulation V
TURNOFF
< P
VCC
< V
CLAMP
(Note 12) 0.05 mV/V
∆V
O(LOAD)
Output Voltage Load Regulation I
TH
/RUN Sinking 5µA, P
VCC
– P
GND
= 8V (Note 12) 3 mV/µA
I
TH
/RUN Sourcing 5µA, P
VCC
– P
GND
= 8V (Note 12) 3 mV/µA
I
POUT_LEAK
P
OUT
Leakage V
PORTN
= 0V, Power MOSFET Off, ● 150 µA
P
OUT
= 57V (Note 13)
I
LIM_HI
Input Current Limit, High Level V
PORTN
= –48V, P
OUT
= –43V (Note 14, 15)
0°C ≤ T
A
≤ 70°C ● 325 375 400 mA
–40°C ≤ T
A
≤ 85°C ● 300 375 400 mA
I
LIM_LO
Input Current Limit, Low Level V
PORTN
= –48V, P
OUT
= –43V (Note 14, 15) ● 80 140 180 mA
f
OSC
Oscillator Frequency V
ITH
/RUN – PGND = 1.3V, P
VCC
– P
GND
= 8V 180 200 240 kHz
DC
ON(MIN)
Minimum Switch On Duty Cycle V
ITH
/RUN – PGND = 1.3V, V
FB
– PGND = 0.8V, 6 8 %
P
VCC
– P
GND
= 8V
DC
ON(MAX)
Maximum Switch On Duty Cycle V
ITH
/RUN – PGND = 1.3V, V
FB
– PGND = 0.8V, 70 80 90 %
P
VCC
– P
GND
= 8V
ELECTRICAL CHARACTERISTICS