ADP3208C ON Semiconductor, ADP3208C Datasheet - Page 26

• Manufacturer Part Number: ADP3208C
• Description: 7-bit,programmable,dual- Phase,mobile,cpu,synchronous Buck Controller
• Manufacturer: ON Semiconductor

ADP3208C
INDUCTOR
CURRENT
VOLTAGE
VOLTAGE
SWITCH
NODE
INPUT
Figure 29. Buck Topology Inductor Current During t
Figure 30. Buck Topology Inductor Current During t
Figure 31. Buck Topology Inductor Current During t
Figure 32. Inductor Current and Switch Node in DCM
t
0
t
1
DRVH
DRVL
Figure 28. Buck Topology
OFF
OFF
OFF
OFF
ON
ON
Q1
Q2
t
2
SWITCH
NODE
L
L
L
L
t
3
t
4
C
C
C
C
VOLTAGE
OUTPUT
LOAD
LOAD
LOAD
0
1
2
and t
and t
and t
Rev. 1 | Page 26 of 41 | www.onsemi.com
LOAD
1
2
3
OUTPUT CROWBAR
To prevent the CPU and other external components from
damage due to overvoltage, the ADP3208C turns off the
DRVH1 and DRVH2 outputs and turns on the DRVL1 and
DRVL2 outputs when the output voltage exceeds the OVP
threshold (1.7 V typical).
Turning on the low-side MOSFETs forces the output capacitor
to discharge and the current to reverse due to current build up
in the inductors. If the output overvoltage is due to a drain-
source short of the high-side MOSFET, turning on the low-side
MOSFET results in a crowbar across the input voltage rail. The
crowbar action blows the fuse of the input rail, breaking the
circuit and thus protecting the microprocessor from
destruction.
When the OVP feature is triggered, the ADP3208C is latched
off. The latch-off function can be reset by removing and
reapplying VCC to the ADP3208C or by briefly pulling the EN
pin low.
Figure 33. Single-Phase Waveforms in DCM with 1 A Load Current
Figure 34. Single-Phase CCM/DCM Frequency vs. Load Current
4
2
3
1
400
350
300
250
200
150
100
50
0
0
SWITCH NODE 5V/DIV
LOW-SIDE GATE DRIVE 5V/DIV
OUTPUT VOLTAGE
9V INPUT
2
INDUCTOR CURRENT
20mV/DIV
5A/DIV
4
LOAD CURRENT (A)
19V INPUT
2µs/DIV
6
8
10
12
14