Step-Down Converter. RT7249 Datasheet


RT7249 Converter. Datasheet pdf. Equivalent


Part Number

RT7249

Description

18V Synchronous Step-Down Converter

Manufacture

Richtek

Total Page 17 Pages
Datasheet
Download RT7249 Datasheet


RT7249
®
RT7249
3A, 18V Synchronous Step-Down Converter with
Adjustable Current Limited Power Switch
General Description
The RT7249 is a high efficiency, monolithic synchronous
step-down DC/DC converter with a power switch. The Buck
converter can deliver up to 3A output current from 4.5V to
18V input supply. The RT7249's current-mode architecture
and external compensation allow the transient response
to be optimized over a wide input range and loads. Cycle-
by-cycle current limit provides protections against shorted
output and soft-start eliminates input current surge during
start-up. The RT7249 also provides under-voltage protection
and thermal shutdown. PWM frequency is adjustable by
the ROSC pin and Power Switch current limit can also be
adjusted by the RLIM pin. The low current (<3μA) in
shutdown mode provides output disconnection, enabling
easy power management in battery-powered systems. The
RT7249 is available in the WQFN-16L 4x4 package.
Marking Information
1A=YM
DNN
1A= : Product Code
YMDNN : Date Code
Features
z Buck Regulator
` 4.5V to 18V Input Voltage Range
` 3A Output Current
` Internal N-Channel MOSFETs
` Current Mode Control
` Adjustable PWM Frequency
` Adjustable Output from 0.8V to 15V
` Adjustable Soft-Start Time
` Stable with Ceramic Output Capacitors
` Cycle-by-Cycle Current Limit
` Input Under-Voltage Lockout
` Output Under-Voltage Protection
` Thermal Shutdown
z Power Switch
` ±15% Current-Limit Accuracy at 1.2A
` Adjustable Current Limit : 75mA to 2580mA
` Meet USB Current-Limiting Requirements
` Reverse Input-Output Voltage Protection
` Built-in Soft-Start
` 120mΩ High-Side MOSFET
` Operating Range : 2.5 V to 5.5 V
z RoHS Compliant and Halogen Free
Simplified Application Circuit
VIN
SW_IN
Enable
Enable
RT7249
VIN LX
BOOT
SW_IN
FB
EN_SW
EN SW_OUT
RLIM COMP
ROSC
PGND
VOUT
SW_OUT
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS7249-00 June 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1

RT7249
RT7249
Applications
z Wireless AP/Router
z Set-Top-Boxes
z Industrial and Commercial Low Power Systems
z LCD Monitors and TVs
z Green Electronics/Appliances
z Point of Load Regulation of High-Performance DSPs
z USB Bus/Self Powered Hubs
z USB Peripheral Ports
z ACPI Power Distribution
z Battery Power Equipment
z 3G/3.5GData Card
Ordering Information
RT7249
Package Type
QW : WQFN-16L 4x4 (W-Type)
Note :
Lead Plating System
G : Green (Halogen Free and Pb Free)
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Pin Configurations
(TOP VIEW)
16 15 14 13
SS 1
12 BOOT
COMP 2
ROSC 3
RLIM 4
PGND
17
11 LX
10 FB
9 SW_IN
56 78
WQFN-16L 4x4
Function Pin Description
Pin No.
Pin Name
Pin Function
1 SS
Soft-Start Time Setting. SS controls the soft-start period. Connect a capacitor
from SS to GND to set the soft-start period. An internal current source (6μA)
charges 0.1μF capacitor and sets the soft-start period to 13.5ms. If SS is floating,
the SS charge current will decrease to 1/128μA and charge 30pF capacitor to set
the soft-start period to 4ms.
2 COMP
Compensation Node. COMP is used to compensate the regulation control loop.
Connect a series RC network from COMP to GND. In some cases, an additional
capacitor from COMP to GND is required.
3 ROSC
Switching Frequency Setting.
4 RLIM
Current Limit Setting. Switch current limit threshold can be set by an external
resistor. Current limit value is from 75mA to 2580mA. The value of 10kΩ ≤ RILIM
210kΩ is recommended.
5 EN_SW
Enable Control Input for Power Switch.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS7249-00 June 2014


Features ® RT7249 3A, 18V Synchronous Step-Down Converter with Adjustable Current Limi ted Power Switch General Description T he RT7249 is a high efficiency, monolit hic synchronous step-down DC/DC convert er with a power switch. The Buck conver ter can deliver up to 3A output current from 4.5V to 18V input supply. The RT7 249's current-mode architecture and ext ernal compensation allow the transient response to be optimized over a wide in put range and loads. Cycleby-cycle curr ent limit provides protections against shorted output and soft-start eliminate s input current surge during start-up. The RT7249 also provides under-voltage protection and thermal shutdown. PWM fr equency is adjustable by the ROSC pin a nd Power Switch current limit can also be adjusted by the RLIM pin. The low cu rrent (<3μA) in shutdown mode provides output disconnection, enabling easy po wer management in battery-powered syste ms. The RT7249 is available in the WQFN -16L 4x4 package. Marking Information 1A=YM DNN 1A= : Product .
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