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FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
General Description
The FS8858 is a low-dropout linear regulator that operates in the input voltage range from +2.5V to +7.0V and delivers 800mA output current. The FS8858 is available in two types, fixed output voltage type or adjustable output voltage type. The fixed output voltage type is preset at an internally trimmed voltage 1.8V, 2.5V, or 3.3V. Other options 1.5V, 2.85V, 3.0V and 3.6V are available by special order only. The output voltage range of the adjustable type is from 1.25V to 5V. The FS8858 consists of a 1.25V bandgap reference, an error amplifier, and a P-channel pass transistor. Other features include short-circuit protection and thermal shutdown protection. The FS8858 devices are available in SOT-223 and TO-252 packages.
Ordering Information
FS8858-xx x x Package Pin Out
GSOT-223 1.IN 2.GND 3.OUT HSOT-223 1.GND 2.IN 3.OUT JSOT-223 1.GND 2.OUT 3.IN PTO-252 1.IN 2.GND 3.OUT RTO-252 1.GND 2.OUT 3.IN Note : For the adjustable voltage types, the GND pin is replaced with the ADJ pin Temperature Range CCommercial Standard Output Voltage (For fixed voltage types only. For adjustable voltage types, these two digits are eliminated.) 15 : 1.5V 18 : 1.8V 25 : 2.5V 29 : 2.85V 30 : 3.0V 33 : 3.3V 36 : 3.6V Default : Adjustable Output Note: The output voltages other than the preset values are available by order only.
Features
Low dropout voltage 600mV at 800mA typ. Adjustable output voltage (FS8858-Cx) or fixed output voltage (FS8858-xxCx) preset at 1.8V, 2.5V, or 3.3V High output voltage accuracy Fixed output voltage : 35mV Adjustable output voltage : 50mV Small output capacitor Output current limit Thermal overload shutdown protection SOT-223 and TO-252 Packages
Part No. FS8858 -xxCG Pin 1 IN
Pin Configurations
SOT-223
Pin 2 GND/ADJ (TAP) IN (TAP) OUT (TAP)
Pin 3 OUT OUT IN
1 2 TO-252 3 FS8858 xxCxxxxx
FS8858 GND/ADJ -xxCH FS8858 GND/ADJ -xxCJ
Applications
Active SCSI Terminators High Efficiency Linear Regulators Monitor Microprocessors Low Voltage Micro-Controllers Post Regulator for Switching Power
Part No. FS8858 -xxCP
Pin 1 IN
Pin 2 GND/ADJ (TAP) OUT (TAP)
Pin 3 OUT IN
FS8858 xxCxxxxx
FS8858 GND/ADJ -xxCR
2
1 Fortune Semiconductor Co.
3 Rev. 1.6
http://www.fsc.com.tw
TEL : +886-2-2809-4742 FAX: +886-2-2809-4874
1/11
TD-0403001
FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
Package Marking Information
EXFS8858-33CJ
FS8858 33CJxxxx xxxxDate Code
EXFS8858-CJADJ type
FS8858 CJxxxx xxxxDate Code
Pin Description
Part NO. FS8858-xxCG FS8858-xxCH FS8858-xxCJ FS8858-xxCP FS8858-xxCR IN Symbol GND/ADJ IN OUT Description Ground pin or adjust terminal pin. Regulator input pin. Regulator output pin.
is the regulator input pin. Supply voltage can range from 2.5V to 7.0V. Bypass with a 10F capacitor to GND.
OUT is the output voltage pin. Sources up to 800mA. Bypass with a 10F capacitor to GND. GND provides the reference for all voltages. ADJ provides VREF=1.25VTyp.for adjustable output voltage.
Fortune Semiconductor Co.
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TD-0403001
Rev. 1.6
FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
Typical Application Circuit
VIN
10F FS8858-Cx 10F
VOUT VREF IADJ
VOUT = VREF x (1 +
R2 ) + I ADJ x R2 R1
FS8858-xxCx
VIN
10F 10F
VOUT
Functional Block Diagrams
IN IN
Current Limit
Current Limit
Shutdown Logic
Thermal Protection
Shutdown Logic
Thermal Protection
OUT
1.25V Bandgap Reference
R1
OUT
1.25V Bandgap Reference
R2
GND Fixed Voltage Type Adjustable Voltage Type
ADJ
Absolute Maximum Ratings
Input voltage VIN to GND -------------------------------------------------------------------------------------------------- 9V Output current limit, I(LIMIT) --------------------------------------------------------------------------------------------- 1.1A Continuous power dissipation, PD SOT-223 ------------------------------------------------------------------------------------------------------------ 1.80W TO-252 ------------------------------------------------------------------------------------------------------------ 2.00W Storage temperature range, TSTG --------------------------------------------------------------------- -55 to +150 Operating junction temperature range ---------------------------------------------------------------- -40 to +125 Lead temperature (soldering, 10sec) ------------------------------------------------------------------------------- 260
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3/11
TD-0403001
Rev. 1.6
FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and function operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Electrical Characteristics
(CIN=10F, COUT=10F, TA=25, unless otherwise noted.) Symbol VIN VOUT Parameter Input Voltage CONDITIONS Min 2.5 VOUT0.035 Typ Max Unit V V V mV mV mA 1.1 VIN>VOUT+0.8V (Fixed Voltage Type) VOUT=0V VIN>VOUT+1.2V (Adjustable Voltage Type) ILOAD=0mA to 800mA, VIN=VOUT+0.8V ILOAD=0mA to 800mA, VIN=VOUT+1.2V IOUT=100mA IOUT=400mA IOUT=800mA VOUT+0.8V4/11
VOUT IMAX ILIMIT ISC IQ IADJ VDROP
Fixed Voltage Type VIN=VOUT+0.8V, IOUT=1mA Output Voltage Adjustable Voltage Type 1.20 VIN=VOUT+1.2V, IOUT=1mA VIN>VOUT+0.8V, VIN 7V (Fixed -35 Voltage Type) Output Voltage Accuracy VIN>VOUT+1.2V, VIN7V (Adjustable -50 Voltage Type) Maximum Output Current 800 Current Limit Short-Circuit Current Ground Pin Current ADJ Pin Current Dropout Voltage (Fixed Output Voltage Version)
7.0 VOUT+ VOUT 0.035 1.25 1.30 +35 +50
A mA A A mV mV mV %/V %/V %/mA %/mA VRMS dB C C
550 90 90 100 400 800 0.3 0.3 0.03 0.15
VLINE
Line Regulation
VLOAD
Load Regulation Output Noise PSRR Thermal Shutdown Temperature Thermal Shutdown Hysteresis Thermal Resistance
eN
PSRR TSD THYS
JA
80 70
TD-0403001
C/W C/W
Rev. 1.6
Fortune Semiconductor Co.
http://www.fsc.com.tw
TEL : +886-2-2809-4742 FAX: +886-2-2809-4874
FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
Typical Operating Characteristics
(CIN=10F, COUT=10F, TA=+25, unless otherwise noted.)
OUTPUT VOLTAGE vs. INPUT VOLTAGE
3.5
GROUND PIN CURRENT vs. AMBIENT TEMPERATURE
70.00
OUTPUT VOLTAGE (V)
GROUND PIN CURRENT (uA)
0mA
60.00 50.00 40.00 30.00 20.00 10.00 0.00
3 2.5 2 1.5 1 0.5 0 0 1 2 3 4 5 6 7 8 9
200mA 500mA
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
INPUT VOLTAGE (V)
*EXModel FS8858-33Cx ILOAD = 0mA
AMBIENT TEMPERATURE ()
DROPOUT VOLTAGE vs. LOAD CURRENT DROPOUT VOLTAGE (mV)
Ron vs. LOAD CURRENT
0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 100 200 300 400 500 600 700 800 900
900 800 700 600 500 400 300 200 100 0 0 100 200 300 400 500 600 700 800 900 1000
Ron ()
LOAD CURRENT (mA)
LOAD CURRENT (mA)
POWER SUPPLY REJECTION RATIO vs. FREQUENCY
-100 -90 -80
GROUND PIN CURRENT vs. LOAD CURRENT
60
GROUND PIN CURRENT (uA)
58 56 54 52 50 48 46 44 0 1 100 200 300 400 500 600 700 800 900
PSRR (db)
-70 -60 -50 -40 -30 -20 -10 0 0.01 0.1 1 10 100 1000
LOAD CURRENT (mA)
FREQUENCY (KHz)
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TD-0403001
Rev. 1.6
FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
OUTPUT VOLTAGE vs. AMBIENT TEMPERATURE
3.36
ADJ PIN CURRENT vs. INPUT VOLTAGE
80
ADJ PIN CURRENT (uA)
OUTPUT VOLTAGE (V)
3.34 3.32 3.3 3.28 3.26 3.24 3.22 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80
70 60 50 40 30 20 10 0 0 1 2 3 4 5 6 7 8 9
INPUT VOLTAGE (V)
AMBIENT TEMPERATURE ()
ADJ PIN CURRENT vs. LOAD CURRENT
52
54.00
ADJ PIN CURRENT vs. AMBIENT TEMPERATURE ADJ PIN CURRENT (uA)
53.00 52.00 51.00 50.00 49.00 48.00 47.00 46.00 45.00 44.00 43.00 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80
ADJ PIN CURRENT (uA)
50 48 46 44 42 40 38 36 0 1 100 200 300 400 500 600 700 800 900
LOAD CURRENT (mA)
AMBIENT TEMPERATURE ()
Vref vs. AMBIENT TEMPERATURE
1.265
1.26
1.255
Vref (V)
1.25
1.245
1.24
ILoad=0
1.235 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80
AMBIENT TEMPERATURE ()
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TD-0403001
Rev. 1.6
FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
Line Transient (IOUT=250mA)
5.0V VIN 4.0V VIN
Line Transient (IOUT=50mA)
5.0V 4.0V
VOUT
CIN 1F COUT 10F 50mV/div
VOUT
CIN 1F COUT 10F 50mV/div
Line Transient (IOUT=100mA)
5.0V 4.0V
Line Transient (IOUT=0mA)
5.0V 4.0V
VIN
VIN
VOUT
CIN 1F COUT 10F 50mV/div
VOUT
CIN 1F COUT 10F 10mV/div
Load Transient
500mA IOUT 0mA IOUT
Load Transient
800mA 0mA
VOUT
CIN 10F COUT 10F 100mV/div
VOUT
CIN 10F COUT 10F 100mV/div
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7/11
TD-0403001
Rev. 1.6
FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
Detail Description
The FS8858 is a low-dropout linear regulator. The device provides preset 1.8V, 2.5V and 3.3V output voltages for output current up to 800mA. Adjustable output voltage and other mask options for special output voltages are also available. As illustrated in function block diagram, it consists of a 1.25V bandgap reference, an error amplifier, a P-channel pass transistor and an internal feedback voltage divider (fixed voltage types). The 1.25V bandgap reference is connected to the error amplifier, which compares this reference with the feedback voltage and amplifies the voltage difference. If the feedback voltage is lower than the reference voltage, the pass-transistor gate is pulled lower, which allows more current to pass to the output pin and increases the output voltage. If the feedback voltage is too high, the pass-transistor gate is pulled up to decrease the output voltage. The output voltage is feed back through an internal resistive divider (or external resistive divider for adjustable output voltage type) connected to OUT pin. Additional blocks include an output current limiter, thermal sensor, and shutdown logic. Internal P-channel Pass Transistor The FS8858 features a P-channel MOSFET pass transistor. Unlike similar designs using PNP pass transistors, P-channel MOSFETs require no base drive, which reduces ground pin current. PNP-based regulators also waste considerable current in dropout when the pass transistor saturates, and use high base-drive currents under large loads. The FS8858 does not suffer from these problems and consumes only 65A (Typ.) of ground pin current under heavy loads as well as in dropout conditions. Output Voltage Selection For fixed voltage type of FS8858, the output voltage is preset at an internally trimmed voltage. The first two digits of part number suffix identify the output voltage (see Ordering Information). For example, the FS8858-33CJ has a preset 3.3V output voltage.
Fortune Semiconductor Co. TEL : +886-2-2809-4742 FAX: +886-2-2809-4874
For adjustable voltage type of FS8858, the output voltage is set by comparing the feedback voltage at adjust terminal to the internal bandgap reference voltage. The reference voltage VREF is 1.25V. The output voltage is given by the equation: VOUT=VREF*(1+R2/R1)+IADJ*R2 (see Typical Application Schematic) Current Limit The FS8858 also includes a fold back current limiter. It monitors and controls the pass transistor's gate voltage, estimates the output current, and limits the output current within 1.1A. Thermal Overload Protection Thermal overload protection limits total power dissipation in the FS8858. When the junction temperature exceeds TJ = +170C, a thermal sensor turns off the pass transistor, allowing the IC to cool down. The thermal sensor turns the pass transistor on again after the junction temperature cools down by 20C, resulting in a pulsed output during continuous thermal overload conditions. Thermal overload protection is designed to protect the FS8858 in the event of fault conditions. For continuous operation, the absolute maximum junction temperature rating of TJ = +170C should not be exceeded. Operating Region and Power Dissipation Maximum power dissipation of the FS8858 depends on the thermal resistance of the case and circuit board, the temperature difference between the die junction and ambient air, and the rate of airflow. The power dissipation across the devices is P = IOUT x (VIN-VOUT). The resulting maximum power dissipation is:
PMAX =
(TJ
JC
- T A ) (TJ - T A ) = JA + CA
Where (TJ-TA) is the temperature difference between the FS8858 die junction and the surrounding air, JC is the thermal resistance of the
8/11 TD-0403001 Rev. 1.6
http://www.fsc.com.tw
FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
package chosen, and CA is the thermal resistance through the printed circuit board, copper traces and other materials to the surrounding air. For better heat-sinking, the copper area should be equally shared between the IN, OUT, and GND pins. If the FS8858 uses a SOT-223 package and this package is mounted on a double sided printed circuit board with two square inches of copper allocated for "heat spreading", the resulting JA is 80 C/W. Based on a maximum junction temperature 170 C with an ambient of 25C, the maximum power dissipation will be: Thermal characteristics were measured using a double-sided board with 1" x 2" square inches of copper area connected to the GND pins for "heat spreading". Input-Output Voltage A regulator's minimum input-output voltage differential, or dropout voltage, determines the lowest usable supply voltage. In battery-powered systems, this will determine the useful end-of-life battery voltage. The FS8858 uses a P-channel MOSFET pass transistor, its dropout voltage is a function of drain-to-source on-resistance (RDS(ON)) multiplied by the output current. VDROPOUT = VIN-VOUT = RDS(ON) x IOUT
PMAX =
(TJ
JC
- T A ) (170 - 25) = = 1.8125W + CA 80
Fortune Semiconductor Co.
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TEL : +886-2-2809-4742 FAX: +886-2-2809-4874
9/11
TD-0403001
Rev. 1.6
FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
Package Outline SOT-223
Fortune Semiconductor Co.
http://www.fsc.com.tw
TEL : +886-2-2809-4742 FAX: +886-2-2809-4874
10/11
TD-0403001
Rev. 1.6
FS8858
800mA Adjustable & Fixed Voltage LDO Linear Regulator
TO-252
Fortune Semiconductor Co.
http://www.fsc.com.tw
TEL : +886-2-2809-4742 FAX: +886-2-2809-4874
11/11
TD-0403001
Rev. 1.6

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