HPL1117V Ver la hoja de datos (PDF) - Unspecified
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HPL1117V Datasheet PDF : 19 Pages
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HPL1117
Application Information
Output Voltage
The HPL1117 develops a 1.25V reference voltage be-
tween the output and the adjust terminal. By placing
a resistor between these two terminals, a constant
Current is caused to flow through R1 and down through
R2 to set the overall output voltage. Normally this
current is chosen to be the specified minimum load
current of 10mA. For fixed voltage devices R1 and R2
are included in the device.
HPL1117
VIN
IN OUT
ADJ
VREF
IADJ
60µA
VOUT = VREF(1+ RR21)+IADJR2
VOUT
R1
R2
Figure 1. Basic Adjustable Regulator
Load Regulation
Rp
PARASITIC
HPL1117
LINE RESISTANCE
VIN
IN
OUT
ADJ
R1
RL
CONNECT
R1 TO CASE
R2
CONNECT
R2 TO LOAD
Figure 2. Connections for Best Load Regulation
Input Capacitor
An input capacitor of 10µF or greater is
recommended. Tantalum, or aluminum electrolytic
capacitors can be used for bypassing. Larger Val-
ues will improve ripple rejection by bypassing the in-
put to the regulator.
When the adjustable regulator is used. Load regula-
tion will be limited by the resistance of the wire con-
necting the regulator to the load. The data sheet speci-
fication for load regulation is measured at the output
pin of the device. Best load regulation is obtained
when the top of the resistor divider (R1) is tied di-
rectly to the output pin of the device, not to the load.
For fixed voltage devices the top of R1 is internally
connected to the output, and the ground pin can be
connected to low side of the load. If R1 were con-
nected to the load, RP is multiplied by the divider
ratio, the effective resistance between the regulator
and the load would be:
Rp X (1+ RR21), Rp = Parasitic Line Resistance
Output Capacitor
The HPL1117 requires an output capacitor to maintain
stability and improve transient response. Proper ca-
pacitor selection is important to ensure proper
operation. The HPL1117 output capacitor selection is
dependent upon the ESR (equivalent series resistance)
of the output capacitor to maintain stability. When the
output capacitor is 10uF or greater, the output capaci-
tor should have an ESR less than 1Ω.This will improve
transient response as well as promote stability. A low-
ESR solid tantalum capacitor works extremely well
and provides good transient response and stability over
temperature.
Copyright HIPAC Semiconductor, Inc.
10
Rev. B.13 - Mar., 2004
www.hipacsemi.com
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