NCP1593AGEVB ON Semiconductor, NCP1593AGEVB Datasheet - Page 5

• Manufacturer Part Number: NCP1593AGEVB
• Description: Power Management IC Development Tools 3A SYNCHRONOUS BUCK REGULATOR
• Manufacturer: ON Semiconductor
• Type: PWM Controllersr

Specifications of NCP1593AGEVB

• Rohs: yes
• Product: Evaluation Boards
• Tool Is For Evaluation Of: NCP1593
• Input Voltage: 4 V to 5.5 V
• Output Voltage: 1.2 V
• Output Current: 3 A

November 2011, Rev.0
Basic Buck Power Topology
The principle of the Buck converter is fairly simple (see Figure 2):
The input voltage source is directly connected to the load through the Buck Inductor when M1 is turned
ON. This is referred to as the ON state (D).
After M1 turns OFF and M2 Turns ON, the inductor maintains its current flow through M2 from ground.
This is known as the OFF state (1-D).
Non- Overlap time is essential for preventing short circuit of the input supply. During this time the body
drain diode of M2 conducts preventing high voltage transients across M2.
Synchronous Buck Converters never allow the inductor current to settle since current can be bi-
directional during the off time. At lighter loads current in the inductor will actually flow in the reverse
direction from Vout through the inductor to ground through the Low side FET M2.
The formulas in Figure 2 derive the input to output transfer function for a Continuous Conduction Buck
Converter in terms of Duty Cycle.
VHSgate
VLSgate
Vsw
IQ1
IL
Vin
Ton
VHSgate
Toff
VLSgate
Figure 4 – Buck Operation
M1
Non-Overlap
Vsw
www.onsemi.com
DN05024/D
M2
L
From Inductor Volt Second
Vout is lower than Vin for D = 0 to 1
C
Balance and:
(
Vin
VinD
(
Vin

Vin
Vo
Vo

L

Vo
VinD 
VoD
)(
Ton
)

D
RLoad


D
)
V 
Vo
Vo
Vo

(
1 (
Vo

L
VoD

di
dt
)(
D
L
Toff
Vout
)
)
5