NB650/NB650H – 6A, 28V, FAST-TRANSIENT, SYNCHRONOUS STEP-DOWN CONVERTERS
FUNCTIONAL BLOCK DIAGRAM
IN
Current Sense
Amplifer
FREQ
+
-
RSEN
5V LDO
VCC
OC
Over-Current
Timer
Refresh
Timer
BST
BSTREG
ILIM
+
-
OFF
Timer
REFERENCE
EN
SS
HS_MOS
HS Ilimit
HS
Driver
Comparator
PWM
0.4V
0.8V
0.6V
xS
xR
Q
1MEG
0
LOGIC
SW
SOFT
START/STOP
VCC
ON
Timer
START
Loop
+
+
-
LS_MOS
FB
LS
Driver
Comparator
Current
Modulator
PGOOD
+
-
+
-
UV
GND
PGOOD
Comparator
UV Detect
Comparator
0
AGND
DRAIN1
VID1
+
-
OV
0
MUX1
1
OV Detect
Comparator
2
0
DRAIN2
VID2
MUX2
1
2
0
VIDSL
Figure 1: Functional Block Diagram
NB650/NB650H Rev. 1.12
10/11/2012
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