Datasheet

SLUU166A - December 2003 − Revised February 2004
20
UCC39002 Advanced Load-Share Controller User’s Guide, HPA027A
R
SENSE
is equal to the actual resistor value used based upon availability of standard values, two 0.002-Ω
resistors are used in parallel:
R
SENSE
+ 1mW
P
RSENSE
is equal to the calculated power dissipation of the actual resistor used and V
Rsense
is equal to its
resultant voltage drop:
P
RSENSE
+ R
SENSE
I
OUT(max)
2
P
RSENSE
+ 0.4 W
V
RSENSE
+ I
OUT(max)
R
SENSE
V
RSENSE
+ 0.02 V
Confirm that V
RSENSE
is much less than ∆V
ADJ
.
Setting the Gain of the Current Sense Amplifier
V
CSO(max)
is equal to the absolute maximum voltage of the CSO pin and, to avoid saturating the internal
amplifier, is limited to:
V
CSO(max)
+ V
DD
* 2V
A
CSA(max)
is equal to the absolute maximum allowable current sense gain before saturation:
A
CSA(max)
+
V
CSO(max)
R
SENSE
I
OUT(max)
A
CSA(max)
+ 150
A
CSA
is equal to the actual current sense amplifier gain chosen for this design:
A
CSA
+ 100
V
CSO
is equal to the resultant output voltage of the current sense amplifier (CSA) and approximate voltage of
the load share (LS) bus:
V
CSO
+ A
CSA
R
SENSE
I
OUT(max)
V
CSO
+ 2V
A
CSA
is equal to the current sense amplifier gain set by R
CSA
1 (R22) and R
CSA2
(R19):
R
CSA(1)
+ 100 kW
R
CSA(2)
+ 1kW
A
CSA
+
R
CSA(1)
R
CSA(2)
A
CSA
+ 100