NCP5661 ON Semiconductor, NCP5661 Datasheet - Page 8

• Manufacturer Part Number: NCP5661
• Description: Ultra-Fast 1.0 A Low Dropout Linear Regulator
• Manufacturer: ON Semiconductor

linear regulator suitable for high power applications,
featuring an ultra−fast response time and low noise without
a bypass capacitor. It is offered in both fixed and adjustable
output versions with voltages as low as 0.9 V. Additional
features, such as Enable and Error Flag (fixed output
version) increase the utility of the NCP5661. It is thermally
robust and includes the safety features necessary during a
fault condition, which provide for an attractive high current
LDO solution for server, ASIC power supplies, networking
equipment applications, and many others.
Input Capacitor
OSCON with an Equivalent Series Resistance (ESR) of
50 mW. It is especially required if the power source is
located more than a few inches from the NCP5661. This
capacitor will reduce device sensitivity and enhance the
output transient response time. The PCB layout is very
important and in order to obtain the optimal solution, the Vin
and GND traces should be sufficiently wide to minimize
noise and unstable operation.
Output Capacitor
stability. The NCP5661 is guaranteed to be stable at an
output capacitance of, C
over the output current range of 10 mA to 1.0 A. For PCB
layout considerations, place the recommended ceramic
capacitor close to the output pin and keep the leads short.
This should help ensure ultra−fast transient response times.
The NCP5661 is a high performance low dropout 1.0 A
The recommended input capacitor value is a 150 mF
Proper output capacitor selection is required to maintain
Figure 15. Load Transient Response
I
out
= 10 mA to 1.0 A
TIME (1.0 ms/Div)
out
> 10 mF with an ESR < 300 mW
V
V
C
C
T
out
J
in
in
out
APPLICATION INFORMATION
= 25°C
= 4.0 V
= 150 mF
= 0.9 V
= 150 mF
NCP5661, NCV5661
http://onsemi.com
8
Adjustable Output Operation
shown in Figure 1. The reference voltage is 0.9 V and the
adjustable pin current is typically 40 nA. A resistor divider
network, R1 and R2, is calculated using the following
formula:
Current Limit Operation
the device is internally clampled to 1.5 A, thus causing the
output voltage to decrease and go out of regulation. This
allows the device never to exceed the maximum power
dissipation.
Error Flag Operation
Low when it drops below the nominal output voltage. Refer
to the electrical characteristics for the threshold values at
which point the Error Flag goes Low. When the NCP5661
is above the nominal output voltage, the Error Flag will
remain at logic High.
between V
of approximately 100 kW is recommended to minimize the
current consumption. No pullup resistor is required if the
Error Flag output is not being used.
The application circuit for the adjustable output version is
As the peak output current increases beyond its limitation,
The Error Flag pin on the NCP5661 will produce a logic
The external pullup resistor needs to be connected
in
(Pin 1) and the Error Flag pin (Pin 5). A resistor
Figure 16. Load Transient Response
R1 + R2
TIME (1.0 ms/Div)
V out
V ref
I
* 1
out
= 1.0 A to 10 mA
V
V
C
C
T
out
J
in
in
out
= 25°C
= 4.0 V
= 150 mF
= 0.9 V
= 150 mF