RT9164A-15GLR Richtek USA Inc, RT9164A-15GLR Datasheet - Page 10

• Manufacturer Part Number: RT9164A-15GLR
• Description: IC REG LDO 1.5V 1A TO252
• Manufacturer: Richtek USA Inc

Specifications of RT9164A-15GLR

• Regulator Topology: Positive Fixed
• Voltage - Output: 1.5V
• Voltage - Input: 3 V ~ 14 V
• Voltage - Dropout (typical): 1.3V @ 1A
• Number Of Regulators: 1
• Current - Output: 1A (Max)
• Current - Limit (min): 1A
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TO-252-3, DPak (2 Leads + Tab), SC-63
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

V
RT9164A
www.richtek.com
10
Application Information
Output voltage adjustment
Like most regulators, the RT9164A regulates the output
by comparing the output voltage to an internally generated
reference voltage. On the adjustable version as shown in
Figure 4, the V
V
should be set to conduct 10mA (minimum output load).
The output voltage is given by the following equation :
V
On fixed versions of RT9164A, the voltage divider is provided
internally.
Input Bypass Capacitor
An input capacitor is recommended. A 10μF tantalum on
the input is a suitable input bypassing for almost all
applications.
Adjust Terminal Bypass Capacitor
The adjust terminal can be bypassed to ground with a
bypass capacitor (C
bypass capacitor prevents ripple from being amplified as
the output voltage is increased. At any ripple frequency,
the impedance of the C
the ripple from being amplified :
(2π x f
The R1 is the resistor between the output and the adjust
pin. Its value is normally in the range of 100-200Ω. For
example, with R1 = 124Ω and f
should be > 11μF.
IN
OUT
OUT
10uF
C
IN
= V
and ADJ. The voltage ratio formed by R1 and R2
RIPPLE
REF
x C
Figure 4. Basic Adjustable Regulator
(1 +
REF
VIN
ADJ
I
65uF
ADJ
is available externally as 1.25V between
R
R
RT9164A
) < R1
2
1
ADJ
ADJ
ADJ
) + I
) to improve ripple rejection. This
VOUT
should be less than R1 to prevent
ADJ
C
RIPPLE
ADJ
R
V
REF
2
= 120Hz, the C
R1
R2
10uF
C
OUT
V
ADJ
OUT
Output Capacitor
RT9164A requires a capacitor from V
compensation feedback to the internal gain stage. This is
to ensure stability at the output terminal. Typically, 10μF
tantalum or 50μF aluminum
range capacitor is sufficient.
The output capacitor does not
limit and increasing its value will increase stability.
C
design.
Load Regulation
When the adjustable regulator is
load regulation is accomplished when the top of the resistor
divider (R1) is connected directly to the output pin of the
RT9164A. When so connected, R
the divider ratio. For Fixed output version, the top of R1 is
internally connected to the output and ground pins can be
connected to low side of the load.
OUT
0.01
0.1
10
= 100μF or more is typical for high current regulator
Region of Stable C
1
0
0.2
C
C
OUT
OUT
= 100uF
= 10uF
Load Current (A)
Figure 5
0.4
OUT
electrolytic with 30mΩ to 2Ω
ESR vs. Load Current
have a theoretical upper
used (Figure 6), the
DS9164A-14 April 2010
0.6
Instable
Stable
Instable
P
OUT
is not multiplied by
to GND to provide
0.8
best
1