MAX1715EEI+T Maxim Integrated Products, MAX1715EEI+T Datasheet - Page 12

• Manufacturer Part Number: MAX1715EEI+T
• Description: IC CNTRLR STP DWN DL 28-QSOP
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck)r

Specifications of MAX1715EEI+T

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 1V, 1.8V, 2.5V, 3.3V, Adj
• Current - Output: 8A
• Frequency - Switching: 200kHz, 300kHz, 420kHz, 540kHz
• Voltage - Input: 2 ~ 28 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-QSOP
• Power - Output: 640mW
• Output Voltage: 1 V to 5.5 V, 3.3 V, 2.5 V
• Output Current: 8 A
• Input Voltage: 2 V to 28 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
Figure 2. Functional Diagram
12
current-limit threshold, and the minimum off-time one-
shot has timed out.
The heart of the PWM core is the one-shot that sets the
high-side switch on-time for both controllers. This fast,
low-jitter, adjustable one-shot includes circuitry that
varies the on-time in response to battery and output
voltage. The high-side switch on-time is inversely pro-
portional to the battery voltage as measured by the V+
OUTPUT1
1.8V
5V INPUT
______________________________________________________________________________________
V
DD
V+
V
DD
OUT1
FB1
SKIP
TON
ON1
ON2
P
V
LX1
BST1
DL1
GOOD
DD
DH1
On-Time One-Shot (TON)
V
DD
V
CC
5μA
CROSSING
CURRENT
I
LIM_
ZERO
LIMIT
9R
R
4.5V TO 28V
BATTERY
(SEE FIGURE 3)
CONTROLLER
PWM
MAX1715
V+
V+
(SEE FIGURE 3)
CONTROLLER
input, and proportional to the output voltage. This algo-
rithm results in a nearly constant switching frequency
despite the lack of a fixed-frequency clock generator.
The benefits of a constant switching frequency are
twofold: first, the frequency can be selected to avoid
noise-sensitive regions such as the 455kHz IF band;
second, the inductor ripple-current operating point
remains relatively constant, resulting in easy design
methodology and predictable output voltage ripple.
The on-times for side 1 are set 15% higher than the
V
CC
PWM
5μA
ZERO
CROSSING
CURRENT
LIMIT
I
LIM_
R
9R
REF
2V
V
DD
BST2
PGND
AGND
OUT2
DH2
LX2
DL2
V
FB2
REF
CC
V
DD
V+
20Ω
OUTPUT2
V
DD
2.5V