9
The OC trip point varies with MOSFETs temperature. To avoid
over-current tripping in the normal operating load range,
determine the R
OCSET
resistor from the equation above with:
1. The maximum r
DS(ON)
at the highest junction temperature.
2. The minimum I
OCSET
from the specification table.
3. Determine I
PEAK
for I
PEAK
> I
OUT(MAX)
+ (擨)/2,
where 擨 is the output inductor ripple current.
For an equation for the output inductor ripple current see the
section under component guidelines titled Output Inductor
Selection.
OUT1 Voltage Program
The output voltage of the PWM converter is programmed to
discrete levels between 1.3V
DC
and 3.5V
DC
. This output is
designed to supply the microprocessor core voltage. The
voltage identification (VID) pins program an internal voltage
reference (DACOUT) through a TTL-compatible 5-bit
digital-to-analog converter. The level of DACOUT also sets
the PGOOD and OVP thresholds. Table 1 specifies the
DACOUT voltage for the different combinations of
connections on the VID pins. The VID pins can be left open
for a logic 1 input, because they are internally pulled up to
+5V by a 10糀 (typically) current source. Changing the VID
inputs during operation is not recommended. The sudden
change in the resulting reference voltage could toggle the
PGOOD signal and exercise the over-voltage protection.
The 11111 VID pin combination resulting in an INHIBIT
disables the IC and the open-collector at the PGOOD pin.
UGATE
OCSET
PHASE
OVER-
CURRENT1
+
-
GATE
CONTROL
VCC
OC1
200?/SPAN>A
V
DS
I
D
V
SET
R
OCSET
V
IN
= +5V
OVER-CURRENT TRIP: V
DS
> V
SET
(i
D
" r
DS
(ON) > I
OCSET
" R
OCSET
)
I
OCSET
+
+
FIGURE 9. OVER-CURRENT DETECTION
PWM
V
PHASE
= V
IN
- V
DS
V
OCSET
= V
IN
- V
SET
DRIVE
HIP6018B
VCC
LGATE
PGND
TABLE 1. V
OUT1
VOLTAGE PROGRAM
PIN NAME
NOMINAL
OUT1
VOLTAGE
DACOUT
VID4 VID3 VID2 VID1 VID0
0
1
1
1
1
1.30
0
1
1
1
0
1.35
0
1
1
0
1
1.40
0
1
1
0
0
1.45
0
1
0
1
1
1.50
0
1
0
1
0
1.55
0
1
0
0
1
1.60
0
1
0
0
0
1.65
0
0
1
1
1
1.70
0
0
1
1
0
1.75
0
0
1
0
1
1.80
0
0
1
0
0
1.85
0
0
0
1
1
1.90
0
0
0
1
0
1.95
0
0
0
0
1
2.00
0
0
0
0
0
2.05
1
1
1
1
1 INHIBIT
1
1
1
1
0
2.1
1
1
1
0
1
2.2
1
1
1
0
0
2.3
1
1
0
1
1
2.4
1
1
0
1
0
2.5
1
1
0
0
1
2.6
1
1
0
0
0
2.7
1
0
1
1
1
2.8
1
0
1
1
0
2.9
1
0
1
0
1
3.0
1
0
1
0
0
3.1
1
0
0
1
1
3.2
1
0
0
1
0
3.3
1
0
0
0
1
3.4
1
0
0
0
0
3.5
NOTE: 0 = connected to GND or V
SS
, 1 = open or connected to 5V
through pull-up resistors.
HIP6018B