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H1117-3.3J View Datasheet(PDF) - Hi-Sincerity Mocroelectronics

Part Name
Description
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H1117-3.3J
HSMC
Hi-Sincerity Mocroelectronics HSMC
H1117-3.3J Datasheet PDF : 6 Pages
1 2 3 4 5 6
HI-SINCERITY
MICROELECTRONICS CORP.
Spec. No. : Preliminary Data
Issued Date : 1998.06.01
Revised Date : 2000.10.01
Page No. : 4/6
Applications Description
Output Voltage Adjustment
Like most regulators, the H1117J regulates the output by
comparing the output voltage to an internally generated
reference voltage. On the adjustable version, the VREF is
V IN
available externally as 1.25V between VOUT and ADJ. The
voltage ratio formed by R1 and R2 should be set to conduct
10mA (minimum output load). The output voltage is given
by the following equation : VOUT =VREF (1+R2/R1) + IADJ R2
On fixed versions of H1117J, the voltage divider is
provided internally.
In
Out
ADJ
I ADJ
10uA
V REF
V OUT
R1
R2
Thermal Protection
H1117J has thermal protection which limits junction
temperature to 150°C. However, device functionality is
only guaranteed to a maximum junction temperature of
VOUT =VREF (1+R2/R1) + IADJ R2
+125°C.
The power dissipation and junction temperature for H1117J in TO-252 package given by
PD=(VIN - VOUT) IOUT, TJUNCTION=TAMBIENT+(PDxθJA), Note : TJUNCTION must not exceed 125°C
Current Limit Protection
H1117J is protected against overload conditions. Current protection is triggered at typically 1.5A.
Stability And Load Regulation
H1117J requires a capacitor from VOUT to GND to provide
compensation feedback to the internal gain stage. This is
to ensure stability at the output terminal. Typically, a 10uF
tantalum or 50uF aluminum electrolytic is sufficient.
Note : It is important that the ESR for this capacitor does
RP
Parasitic
Line Resistance
In
Out
V IN
Adj
not exceed 0.5.
The output capacitor does not have a theoretical upper
R1
Connect
R1 to Case
RL
limit and increasing its value will increase stability. COUT =
R2
100 uF or more is typical for high current regulator design.
H1117J load regulation is limited by the resistance of the
wire connecting it to the load(RP). For the adjustable
version, the best load regulation is accomplished when the
top of the resistor divider(R1) is connected directly to the
Connect
R2 to Load
output pin of the H1117J. When so connected, RP is not
multiplied by the divider ratio. For fixed output versions,
the top of R1 is internally connected to the output and ground pin can be connected to low side of the load as a
negative side sense if, so desired.
Thermal Consideration
The H1117J series contain thermal limiting circuitry designed to protect itself for over-temperature conditions.
Even for normal load conditions, maximum junction temperature ratings must not be exceeded. As mention in
thermal protection section, we need to consider all sources of thermal resistance between junction and ambient.
It contains junction-to-case, case-to-heat-sink interface and heat sink resistance itself. An additional heat sink is
applied externally sometimes. It can increase the maximum power dissipation. For example, the equivalent
junction temperature of 300mA output current is 115°C without external heat sink. Under the same junction
temperature IC can operates 500mA with an adequate heat sink. Therefore, to attach an extra heat sink is
recommended.
Junction-to-case thermal resistance is specified from the IC junction to the bottom of the case directly below the
die. The bonding wires are appending paths. The former is the lowest resistance path. Proper mounting is
required to ensure the best possible thermal flow this area of the package to the heat sink. Thermal compound at
the case-to-heat-sink interface is strongly recommended. The case of all devices in this series is electrically
connected to the output. Therefore, if the case of the device must be electrically isolated, a thermally conductive
spacer can be used, as long its thermal resistance is considered.
HSMC Product Specification
 

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