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PT5108X
High-PSRR 500mA LDO
GENERAL DESCRIPTION
The PT5108 is a low-dropout voltage regulator designed for portable applications that require both low noise performance
and board space. Its PSRR at 1kHz is better than 70dB. The PT5108’s performance is ideal for battery powered systems for
delivering low dropout voltage and low quiescent current. An optional external bypass capacitor reduces the output noise and
increases PSRR.
The device can be used for mobile phone and similar battery powered wireless applications. It provides up to 500mA, from a
2.5V to 5.5V input. The PT5108 consumes less than 0.1µA in shutdown mode and has fast turn-on time less than 150µs. The
PT5108 is available in 5 pin SOT-23 package (Pd free). Selected performances are specified for 40°C to +85°C temperature
range. The output voltage is available in the range of 1.5V to 5.0V.
FEATURES
APPLICATIONS
„ 2.5V to 5.5V input range
„ CDMA/GSM mobile phone
„ 72dB PSRR @1kHz, Vin = Vout + 1V
„ Handless telephone
„ < 1uA quiescent current at shutdown mode
„ WLAN and Bluetooth appliances
„ Fast turn on time: 150us (typical)
„ PDAS/MP3 handsets
„ 290mV maximum dropout voltage with 400mA load
„ Battery powered portable devices
„ Thermal shutdown and short-circuit current limit
„ 1.5, 1.8, 2.0, 2.5V, 2.6V, 2.7V, 2.8V, 2.85V, 2.9V, 3.0V, 3.1V, 3.2V,
3.3V, 4.7V, 4.8V, 4.9V and 5.0V output standard
„ Miniature SOT-23-5 package (Pd free)
TYPICAL APPLICATIONS
VIN
VIN VOUT
CIN
1uF
VEN
BYPASS
CBP *
10nF
GND
VOUT
COUT
1uF
COUT: Recommended ceramic capacitor
CBP: The optional bypass capacitor for noise reduction
-30
-35
-40
-45
-50
-55
-60
-65
-70
-75
100
Ripple Rejection vs Frequency
VIN(DC) = 3.0V
VIN(AC) = 400mV
VOUT = 2.5V
COUT = 1uF
CBP = 10nF
IOUT=50mA
IOUT=100mA,150mA
1k 10k
Frequency (Hz)
100k
micro-bridge
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ORDERING INFORMATION*
Package Temperature Range Output Voltage (V)
1.5
1.8
2.0
2.5
SOT-23-5 -4
2.6
2.7
2.8
2.85
2.9
3.0
3.1
3.2
3.3
4.7
4.8
4.9
5.0
Part Number
PT5108X23E-15
PT5108X23E-18
PT5108X23E-20
PT5108X23E-25
PT5108X23E-26
PT5108X23E-27
PT5108X23E-28
PT5108X23E-285
PT5108X23E-29
PT5108X23E-30
PT5108X23E-31
PT5108X23E-32
PT5108X23E-33
PT5108X23E-47
PT5108X23E-48
PT5108X23E-49
PT5108X23E-50
* All parts are supplied as 3000 units, tape and reel.
PACKAGES
VEN GND
32
VIN
1
PT5108
4
BYPASS
SOT23-5
5
VOUT
PT5108X
High-PSRR 500mA LDO
PIN DESCRIPTIONS
Name
VIN
GND
VEN
BYPASS
SOT-23
1
2
3
4
VOUT
5
Description
Input of LDO
Ground
Enable Input Logic, Enable High
Optional bypass capacitor for noise reduction
Output of LDO
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PT5108X
High-PSRR 500mA LDO
SIMPLIFIED BLOCK DIAGRAM
VIN
VEN
BYPASS
Bandgap
Reference
1.25V
Quick Start
Cirucut
Current
Sense &
Current Limit
Thermal
Shutdown
VOUT
R1
Figure 1. Graph the PT5108
major functional blocks
R2
GND
In Figure 1, the block of Bandgap Reference provides the reference voltage of the LDO.
The resistor and bypass capacitor connected to the BYPASS pin together form a low pass filter to attenuate the
noise generated at the reference block.
The Quick Start Circuit block injects a short-time current to charge the bypass capacitor very fast during the
turn-on period for the purpose of speed up the output voltage settlement. The fast charging stops when the bypass
capacitor voltage reaches 95% of 1.23V (typical).
The op amp block is used as the error amplifier of the LDO by compare the reference with the output feedback
voltages. Its output controls the gate of a large PMOS driver and hereby adjusts the output voltage.
The resistor R1 and R2 form a voltage divider to provide the feedback voltage.
The Current Sense & Limit block senses the LDO output current and limits the output current from being too
high. This is mostly a short circuit protection feature.
ABSOLUTE MAXIMUM RATINGS
PARAMETER
VIN Range
VALUE
-0.3~6.0V
VOUT Range
-0.3~(VIN+0.3)< 6.0V
VEN Range
Maximum Power
Dissipation (Note1)
SOT23-5
-0.3~6.0V
364
Junction Temp.
150
Storage Temp.
-65~150
Lead Temp. (Note2)
235
ESD Rating, HBM
2
UNIT
V
V
V
mW
°C
°C
°C
KV
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