MAX1714BEEE Maxim Integrated Products, MAX1714BEEE Datasheet - Page 20

• Manufacturer Part Number: MAX1714BEEE
• Description: Current Mode PWM Controllers
• Manufacturer: Maxim Integrated Products

Specifications of MAX1714BEEE

• Number Of Outputs: 1
• Output Voltage: 1 V to 5.5 V
• Output Current: 3000 mA
• Mounting Style: SMD/SMT
• Package / Case: QSOP-16
• Switching Frequency: 600 KHz
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Synchronous Pin: No
• Topology: Buck
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

capacitors close to the CPU. Resistance values higher
than 5mΩ just improve the stability (which can be
observed by examining the load-transient response
characteristic as shown in the Typical Operating
Characteristics). Avoid adding excess PC board trace
resistance, as there’s an efficiency penalty; 5mΩ is suffi-
cient for a 7A circuit.
V
requirement. In this example, the switching frequency
has been increased to 600kHz and the inductor value
has been reduced to 0.5µH (compared to 300kHz and
1.5µH for the standard 8A circuit) in order to minimize the
energy transferred from inductor to capacitor during
load-step recovery. The overshoot must be calculated to
avoid tripping the OVP latch. The efficiency penalty for
operating at 600kHz is about 2% to 3%, depending on
the input voltage.
An optional 1kΩ resistor is placed in series with OUT.
This resistor attenuates high-frequency noise in some
boards, which can cause double pulsing.
High-Speed Step-Down Controller
for Notebook Computers
20
Figure 8. Feedback Mux
SOAR
TO ERROR AMP
______________________________________________________________________________________
determines the minimum output capacitance
R
ESR
≥
FIXED
2.5V
FIXED
3.3V
2FC
1
OUT
MAX1714
0.2V
2V
OUT
FB
The MAX1714’s Dual Mode™ operation allows the selec-
tion of common voltages without requiring external com-
ponents (Figure 8). Connect FB to AGND for a fixed
+2.5V output or to V
directly to OUT for a fixed +1.0V output.
The output voltage can be adjusted with a resistor-
divider if desired (Figure 9). The equation for adjusting
the output voltage is:
where V
The most efficient and overall cost-effective solution for
stepping down a high-voltage battery to a very low out-
put voltage is to use a single-stage buck regulator that’s
powered directly from the battery. However, there may
be situations where the battery bus can’t be routed near
the CPU, or where space constraints dictate the smallest
possible local DC-DC converter. In such cases, the 5V
powered circuit of Figure 10 may be appropriate. The
reduced input voltage allows a higher switching frequen-
cy and a much smaller inductor value.
Careful PC board layout is critical to achieving low
switching losses and clean, stable operation. The switch-
ing power stage requires particular attention (Figure 11).
If possible, mount all of the power components on the
top side of the board with their ground terminals flush
against one another. Follow these guidelines for good PC
board layout:
• Keep the high-current paths short, especially at the
• Connect AGND and PGND together close to the IC.
• Keep the power traces and load connections short.
Dual Mode is a trademark of Maxim Integrated Products.
ground terminals. This practice is essential for stable,
jitter-free operation.
For the MAX1714B, these grounds are connected
internally to the GND pin. Carefully follow the ground-
ing instructions under step 4 of the Layout Procedure.
This practice is essential for high efficiency. Using
thick copper PC boards (2 oz vs. 1 oz) can enhance
full-load efficiency by 1% or more. Correctly routing
PC board traces is a difficult task that must be
approached in terms of fractions of centimeters,
FB
Setting V
2-Stage (5V Powered) Notebook CPU
is 1.0V.
V
OUT
CC
OUT
PC Board Layout Guidelines
=
for a +3.3V output, or connect FB
V
FB
with a Resistor-Divider



Fixed Output Voltages
1
+
R2
R1



Buck Regulator