MAX1954AEUB-T Maxim Integrated Products, MAX1954AEUB-T Datasheet - Page 8

• Manufacturer Part Number: MAX1954AEUB-T
• Description: Current Mode PWM Controllers
• Manufacturer: Maxim Integrated Products

Specifications of MAX1954AEUB-T

• Number Of Outputs: 1
• Duty Cycle (max): 93 %
• Output Voltage: 0.8 V to 4.95 V
• Output Current: 25000 mA
• Mounting Style: SMD/SMT
• Package / Case: uSOP-10
• Switching Frequency: 360 KHz
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Synchronous Pin: No
• Topology: Boost, Buck
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Low-Cost, Current-Mode PWM Buck
Controller with Foldback Current Limit
During the second half of the cycle, the high-side
MOSFET turns off and the low-side MOSFET turns on. The
inductor releases the stored energy as the current ramps
down, providing current to the output. The output capaci-
tor stores charge when the inductor current exceeds the
required load current and discharges when the inductor
current is lower, smoothing the voltage across the load.
Under overload conditions, when the inductor current
exceeds the current limit (see the Current-Limit Circuit
section), the high-side MOSFET is not turned on at the ris-
ing clock edge and the low-side MOSFET remains on to
let the inductor current ramp down.
8
_______________________________________________________________________________________
COMP
FB
2.36V
CLAMP
DIGITAL-TO-ANALOG
COMPARATOR
SHUTDOWN
0.5V
AMPLIFIER
SOFT-START
CONVERTER
REFERENCE
ERROR
AND
FOLDBACK CURRENT-
LIMIT CIRCUITRY
THERMAL
LIMIT
COMPENSATION
CLOCK
GND
SLOPE
CIRCUITRY
CONTROL
The MAX1954A operates in a forced-PWM mode; there-
fore, the controller maintains a constant switching fre-
quency, regardless of load, to allow for easier post-
filtering of the switching noise.
The current-sense circuit amplifies the current-sense
voltage (the high-side MOSFET’s on-resistance
(R
fied current-sense signal and the internal slope-compen-
sation signal are summed (V
the PWM comparator’s inverting input. The PWM com-
parator shuts off the high-side MOSFET when V
exceeds the integrated feedback voltage (V
PWM
DS(ON)
SHORT-CIRCUIT
CURRENT-LIMIT
CIRCUITRY
UVLO
) multiplied by the inductor current). This ampli-
IN
CURRENT-LIMIT
COMPARATOR
CIRCUITRY
CURRENT-
SENSE
MAX1954A
Functional Diagram
Current-Sense Amplifier
SUM
) together and fed into
IN
HSD
BST
DH
PGND
LX
DL
COMP
SUM
).