NCT3720S/ S-L
Nuvoton
Maximum 2A, Ultra Low
Dropout Regulator
NCT3720S/ NCT3720S-L
I
Publication Release Date: Jan, 2011
Version: A3
NCT3720S/ S-L
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Table of Contents –
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
GENERAL DESCRIPTION ......................................................................................................... 1
FEATURES ................................................................................................................................. 1
APPLICATIONS .......................................................................................................................... 1
PIN CONFIGURATION AND DESCRIPTION ............................................................................ 2
TYPICAL APPLICATION CIRCUIT............................................................................................. 2
BLOCK DIAGRAM ...................................................................................................................... 3
FUNCTIONAL DESCRIPTION ................................................................................................... 3
ELECTRICAL CHARACTERISTIC ............................................................................................. 6
TYPICAL OPERATING WAVEFORMS ...................................................................................... 9
PACKAGE DIMENSION ........................................................................................................... 11
ORDERING INFORMATION .................................................................................................... 12
TOP MARKING SPECIFICATION ............................................................................................ 12
REVISION HISTORY ................................................................................................................ 13
II
Publication Release Date: Jan, 2011
Version: A3
NCT3720S/ S-L
1. GENERAL DESCRIPTION
The NCT3720S/S-L is a high performance positive voltage regulator which designed for use in
applications requiring very low input voltage and very low dropout voltage up to 2A(peak)
current rating. It operates with a VIN as low as 1.0V and control voltage 3V with output voltage
programmable as low as 0.8V. The significant feature includes ultra low dropout, ideal for
applications where VOUT is very close to VIN. Additionally, there is an enable pin to further
reduce power dissipation while shutdown. The NCT3720S/S-L provides excellent regulation
over variations in line, load and temperature, and provides a Power Good indicator to indicate
if the voltage level of output voltage reaches 90% of its rating value.
2. FEATURES
Maximum 2A Ultra Low-Dropout Voltage Regulator
High Accuracy Output Voltage ±1.5%
Adjustable Output from 0.8V
Typically 150mV Dropout at 2A
Input Voltage as low as 1.0V
Power Good Indicator
Thermal and Over Current Protection
EN internal Pull High (NCT3720S) and Internal Pull Low Available (NCT3720S-L)
SOP-8 150mil with Exposed Pad Package
Lead Free (ROHS Compliant) and Halogen Free Package
3. APPLICATIONS
Desktop PCs, Notebooks, and Workstations
Graphics Card
Set Top Boxes, Digital TVs and Printers
Portable instruments
uP/ASIC/DSP/FPGA Core and I/O Supplies
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Publication Release Date: Jan, 2011
Version: A3
NCT3720S/ S-L
4. PIN CONFIGURATION AND DESCRIPTION
PIN NO.
PIN NAME
I/O
FUNCTION
1
2
3
4
5
6
7
8
9(Exposed
pad)
PG
EN
VIN
VCNTL
NC
VOUT
FB
GND
--
O
I
P
P
N/A
P
I
P
--
Power Good indicator. This is an open drain output. Connect it
with a resistor to power source.
Chip Enable Input. It is high active.
Supply Input Voltage.
Supply Input Voltage for Control Circuit.
No Internal Connection.
Output Voltage. Vout = 0.8*(1+R1/R2)
Feedback Input.
Ground.
The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
5. TYPICAL APPLICATION CIRCUIT
VCNTL
CNTL
VOUT
VOUT
1uF
FB
Enable
Singal
EN
C
(optional)
R1
10uF
R2
PG
VIN
VIN
GND
100k
10uF
VOUT
PG
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Publication Release Date: Jan, 2011
Version: A3
NCT3720S/ S-L
6. BLOCK DIAGRAM
GND
EN
CNTL
VIN
POR
OTP
Softstart &
Control Logic
OCP
FB
0.8V
Driver
VOUT
PG
0.72V
7. FUNCTIONAL DESCRIPTION
The NCT3720S/S-L is intended for applications where high current capability and very low
dropout voltage are required. It provides a very simple, low cost solution that uses very little pcb
real estate. Additional features include an enable pin to allow for a very low power consumption at
disable, and a fully adjustable output.
Output Voltage Selection
The output voltage of NCT3720S/S-L is adjustable from 0.8V to (VIN-VDROP) by external voltage
divider resisters as shown in Typical Application Circuit. The value of resisters R1 and R2 should
be more than 10kΩ to reduce the power loss. The VCNTL must be greater than (VOUT + 1.5V).
Input capacitor
Publication Release Date: Jan, 2011
Version: A3
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