ADP3209 ON Semiconductor, ADP3209 Datasheet - Page 13

• Manufacturer Part Number: ADP3209
• Description: 5-bit, Programmable, Single-phase, Synchronous Buck Controller
• Manufacturer: ON Semiconductor

THEORY OF OPERATION
The ADP3209 is a ramp-pulse-modulated (RPM) controller for
synchronous buck Intel GMCH core power supply. The internal
5-bit VID DAC conforms to the Intel IMVP-6+ specifications. The
ADP3209 is a stable, high performance architecture that includes
•
•
•
•
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
C
× I
R
RAMP
1V
COMP
VRMP
R
A
400ns
C
FB
Q
Q
C
A
FB
FLIP-FLOP
S
RD
+
FLIP-FLOP
R
+
C
S
RD
FB
B
VDC
V
+ –
CS
FBRTN
Q
Q
Rev. 2 | Page 13 of 32 | www.onsemi.com
30mV
Figure 19. RPM Mode Operation
LLINE
–
+
R2
CSCOMP
R2
GATE DRIVER
1V
OPERATION MODES
The ADP3209 runs in RPM mode for the purpose of fast
transient response and high light load efficiency. During the
following transients, the ADP3209 runs in PWM mode:
•
•
•
IN
DCM
DRVH
DRVL
BST
SW
Soft start
Soft transient: the period of 100 μs following any VID change
Current overload
R1
R1
CSREF
CSFB
R
C
DRVH
DRVL
CS
CS
BST
SW
5V
VCC
R
PH
R
I
L
ADP3209
LOAD