MAX17007EVKIT+ Maxim Integrated Products, MAX17007EVKIT+ Datasheet - Page 23

• Manufacturer Part Number: MAX17007EVKIT+
• Description: KIT EVAL FOR MAX17007
• Manufacturer: Maxim Integrated Products
• Series: Quick-PWM™r

Specifications of MAX17007EVKIT+

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 2, Non-Isolated
• Voltage - Output: 1.2V, 1.5V
• Current - Output: 12A, 12A
• Voltage - Input: 7 ~ 24V
• Regulator Topology: Buck
• Frequency - Switching: 270kHz, 330kHz
• Board Type: Fully Populated
• Utilized Ic / Part: MAX17007
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Figure 7. “Valley” Current-Limit Threshold Point
The current-limit circuit employs a unique “valley” cur-
rent-sensing algorithm that senses the inductor current
across the output current-sense element—inductor
DCR or current-sense resistor, which generates a volt-
age between CSH_ and CSL_. If the current exceeds
the valley current-limit threshold during the low-side
MOSFET conduction time, the PWM controller is not
allowed to initiate a new cycle. The valley current-limit
threshold is set by the four-level ILIM_ pin, with selec-
table limits of 15mV, 30mV, 45mV, and 60mV.
The actual peak current is greater than the valley cur-
rent-limit threshold by an amount equal to the inductor
ripple current (Figure 7). Therefore, the exact current-
limit characteristic and maximum load capability are a
function of the inductor value and battery voltage.
When combined with the undervoltage protection cir-
cuit, this current-limit method is effective in almost
every circumstance. See Figure 8.
0
Core Controllers for Notebook Computers
Valley Current-Limit Protection
______________________________________________________________________________________
I
LIM(VAL)
Dual and Combinable QPWM Graphics
TIME
= I
LOAD(MAX)
( )
1-
LIR
2
I
I
I
PEAK
LOAD
LIMIT
In forced-PWM mode, the MAX17007/MAX17008 also
implement a negative current limit to prevent excessive
reverse inductor currents when V
The negative current-limit threshold is set to approxi-
mately 120% of the positive current limit.
In combined mode, ILIM1 sets the per-phase current
limit for both phases.
The DH and DL drivers are optimized for driving mod-
erate-sized high-side, and larger low-side power
MOSFETs. This is consistent with the low duty factor
seen in notebook applications, where a large V
V
sources and sinks 1.2A, and the low-side gate driver
(DL) sources 1.0A and sinks 2.4A. This ensures robust
gate drive for high-current applications. The DH floating
high-side MOSFET driver is powered by internal boost
switch charge pumps at BST, while the DL synchro-
nous-rectifier driver is powered directly by the 5V bias
supply (V
Figure 8. Current-Limit Block Diagram
OUT
SKIP
ILIM
CSH
CSL
differential exists. The high-side gate driver (DH)
DD
QUAD-LEVEL
).
DECODE
MOSFET Gate Drivers (DH, DL)
OUT
is sinking current.
CURRENT-
SENSE
GAIN
VALLEY
CURRENT
LIMIT
ZERO
CROSSING
IN
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