ADP3211 ON Semiconductor, ADP3211 Datasheet - Page 12

• Manufacturer Part Number: ADP3211
• Description: 7-bit, Programmable, Single-phase, Synchronous Buck Controller
• Manufacturer: ON Semiconductor

Theory of Operation
controller for synchronous buck Intel GMCH and CPU core
power supply. The internal 7−bit VID DAC conforms to the
Intel IMVP−6.5 specifications. The ADP3211 is a stable,
high performance architecture that includes
•
•
•
•
The ADP3211 is a Ramp Pulse Modulated (RPM)
High speed response at the lowest possible switching
frequency and minimal count of output decoupling
capacitors
Minimized thermal switching losses due to lower
frequency operation
High accuracy load line regulation
High power conversion efficiency with a light load by
automatically switching to DCM operation
I
R
= A
R
X I
C
R
RAMP
COMP
1.0 V
30mV
VRMP
R
C
400ns
A
FB
Q
Q
C
FB
A
R2
FLIP−FLOP
R2
FLIP−FLOP
S
RD
+
C
R
1.0 V
S
RD
+
VDC
FBRTN
B
Figure 19. RPM Mode Operation
B
Q
V
R1
Q
CS
R1
http://onsemi.com
LLINE
12
–
+
CSCOMP
DCM
GATE DRIVER
IN
Operation Modes
transient response and high light load efficiency. During
the following transients, the ADP3211 runs in PWM mode:
•
•
•
The ADP3211 runs in RPM mode for the purpose of fast
Soft−Start
Soft transient: the period of 110 ms following any VID
change
Current overload
DRVH
DRVL
BST
SW
CSFB
DRVH1
CSREF
DRVL1
R
5.0 V
C
SW1
CS
CS
BST1
R
VCC
PH
R
I
L
LOAD