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NR421A Datasheet Preview

NR421A Datasheet

Synchronous Switching Regulator

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Buck type Synchronous Switching Regulator IC
NR421A
DATA SHEET
General Descriptions
The NR421A is Synchronous Rectification buck
regulator ICs integrates PowerMOSFETs. With the
current mode control, low ESR capacitors such as
ceramic capacitors can be used. It has achieved a
high efficiency by the synchronous rectification
system. The ICs have protection functions such as
Over-Current Protection (OCP), Under-Voltage
Lockout (UVLO) and Thermal Shutdown (TSD).
Soft starting time can be set up by selecting an
external capacitor value. The ON/OFF pin (EN Pin)
turns the regulator ON/OFF. The NR421A is
available in an 8-pin HSOP package with an exposed
thermal pad on the back side.
Features & Benefits
For excellent heat dissipation, HSOP8 package with
the heat-slug is adopted.
Current mode PWM control
Up to 94% efficiency
Stable with low ESR ceramic output capacitors
Built-in protection function
Drooping type Over Current Protection (OCP) with
Auto-restart
Thermal Shutdown (TSD) with Auto-restart
Under Voltage Lockout(UVLO)
By the internal Phase Compensation, external
component count reduction
Adjustable Soft-Start with an external capacitor
Output ON/OFF function (Enable)
Basic Circuit Connection
Package
HSOP8
Thermally enhanced 8-Pin package
*Image: Not to scale
Electrical Characteristics
Input voltage range VIN = 4.5 to 18V
Output voltage range VO=0.8V to 14V
Operation Frequency FSW= 350kHz Fixed
Applications
LCD-TV
Blu-ray
Power supply for digital consumer
NR421A
NR421A-DSE Rev.1.2
SANKEN ELECTRIC CO.,LTD
1
2016.04.27
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2016




SANKEN

NR421A Datasheet Preview

NR421A Datasheet

Synchronous Switching Regulator

No Preview Available !

NNNRNN4N21A
CONTENTS
General Descriptions ------------------------------------------------------------------------------------------ 1
1. Electrical Characteristics -------------------------------------------------------------------------------- 3
1.1 Absolute Maximum Ratings----------------------------------------------------------------------- 3
1.2 Recommended Operating Conditions ----------------------------------------------------------- 3
1.3 Electrical Characteristics -------------------------------------------------------------------------- 4
2. Block Diagram & Pin Functions ----------------------------------------------------------------------- 5
2.1 Block Diagram --------------------------------------------------------------------------------------- 5
2.2 Pin Asignments & Functions ---------------------------------------------------------------------- 6
3. Typical Application Circuit ----------------------------------------------------------------------------- 7
4. Allowable package power dissipation ----------------------------------------------------------------- 7
5. Package Outline ------------------------------------------------------------------------------------------- 9
5.1 Outline, Size ------------------------------------------------------------------------------------------ 9
6. Marking --------------------------------------------------------------------------------------------------- 10
7. Operational Descriptions ------------------------------------------------------------------------------ 11
7.1 PWM(Pulse Width Modulation) Output Control ------------------------------------------- 11
7.2 Enable Function (EN:Remote ON / OFF operation of the Regulator) ------------------ 12
7.3 Soft-start Function (SS) -------------------------------------------------------------------------- 13
7.4 Over Current Protection (OCP) ---------------------------------------------------------------- 15
7.5 Thermal Shutdown (TSD) ----------------------------------------------------------------------- 15
8. Design Notes ---------------------------------------------------------------------------------------------- 16
8.1 External Components ---------------------------------------------------------------------------- 16
8.1.1 Inductor L1 ----------------------------------------------------------------------------------- 16
8.1.2 Input Capacitor CIN------------------------------------------------------------------------- 19
8.1.3 Output Capacitor CO ----------------------------------------------------------------------- 19
8.1.4 Output Voltage Setup Resistor RFB1 & RFB2 ------------------------------------------- 21
8.1.5 External Bootstrap Diode for Low Input Voltage------------------------------------- 23
8.1.6 Free-wheeling diode D1 (option) --------------------------------------------------------- 23
8.2 Pattern Design ------------------------------------------------------------------------------------- 24
8.2.1 Input / Output Capacitors(CIN,CO) ------------------------------------------------------ 24
8.2.2 PCB Layout & Recommended Land Pattern ------------------------------------------ 25
8.3 Applied Design ------------------------------------------------------------------------------------- 27
8.3.1 Spike Noise Reduction(1) ------------------------------------------------------------------ 27
8.3.2 Spike Noise Reduction(2) ------------------------------------------------------------------ 27
8.3.3 Attention about the insertion of the bead-core ---------------------------------------- 28
8.3.4 Reverse Bias Protection -------------------------------------------------------------------- 28
9. Typical characteristics (Ta=25°C) ------------------------------------------------------------------- 29
10. Packing specifications ---------------------------------------------------------------------------------- 31
10.1 Taping & Reel outline ---------------------------------------------------------------------------- 31
IMPORTANT NOTES ------------------------------------------------------------------------------------- 32
NR421A-DSE Rev.1.2
SANKEN ELECTRIC CO.,LTD
2
2016.04.27
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2016


Part Number NR421A
Description Synchronous Switching Regulator
Maker SANKEN
PDF Download

NR421A Datasheet PDF






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