zldo485 Zetex Semiconductors plc., zldo485 Datasheet

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zldo485

Manufacturer Part Number
zldo485
Description
Zldo485 - 4.85 Volt Ultra Low Dropout Regulator
Manufacturer
Zetex Semiconductors plc.
Datasheet

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Part Number:
ZLDO485
Manufacturer:
ZETEX
Quantity:
20 000
4.85 VOLT ULTRA LOW DROPOUT
REGULATOR
ISSUE 2 - MAY 1997
DEVICE DESCRIPTION
The ZLDO Series low dropout linear
regulators operate with an exceptionally
low dropout voltage, typically only 30mV
with a load current of 100mA. The regulator
series features output voltages in the range
2.7 to 18 volts, this device provides an output
voltage of 4.85 volts.
The ZLDO485 consumes a typical quiescent
current of only 1mA and is rated to supply
load currents up to 300mA. A battery low flag
is available to indicate potential power fail
situations. If the input voltage falls to within
200mV of the regulated output voltage then
the error output pulls low. The device also
features an active high disable control. Once
disabled the ZLDO quiescent current falls to
typically 11 A.
The ZLDO devices are packaged in Zetex
SM8 8 pin small outline surface mount
package, ideal for applications where space
saving is important. The device low dropout
voltage, low quiescent current and small size
make it ideal for low power and battery
powered applications. Battery powered
circuits can make particular use of the low
battery flag and shutdown features.
Shutdown
Control
THERMAL
SHUTDOWN
SHUTDOWN
Low Battery Flag
LOW BATTERY
COMPARATOR
CIRCUIT
BIAS
4-71
Gnd
FEATURES
APPLICATIONS
Very low dropout voltage
6mV dropout at 10mA output
30mV dropout at 100mA output
100mV dropout at 300mA output
Other voltages available
1mA quiescent (typ) at 300mA output
4.85 volt fixed output
Low quiescent current
Low battery flag
Shutdown control
Surface mount package
Battery powered devices
Portable instruments
Portable communications
Laptop/Palmtop computers
Electronic organisers
BANDGAP
REFERENCE
OUTPUT
DRIVE
ZLDO485
Shaping
Vo
Vin
Cs

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zldo485 Summary of contents

Page 1

... The regulator series features output voltages in the range 2 volts, this device provides an output voltage of 4.85 volts. The ZLDO485 consumes a typical quiescent current of only 1mA and is rated to supply load currents up to 300mA. A battery low flag is available to indicate potential power fail situations ...

Page 2

... ZLDO485 ABSOLUTE MAXIMUM RATING Input Supply Voltage Range Shutdown Input Voltage Range Low Battery Output Voltage Range ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated) T Parameter SYMBOL Output voltage Output voltage o temperature coefficient T Line regulation V Load regulation V Dropout voltage V in (Note3) ...

Page 3

... A capacitor of 10pF wired from this pin to the output pin (pin 5) gives optimum stability. Improved AC can be achieved by reducing the value of this capacitor but stability may be impaired for some load conditions. 4-73 ZLDO485 change x 1000000 temperature change O measured out 2 ...

Page 4

... ZLDO485 TYPICAL CHARACTERISTICS 1800 (out) 1600 1400 1200 1000 800 600 400 200 0 100 1K Frequency (Hz) Output Impedance vs. Frequency 4.89 Io= 10mA (in) 4.88 4.87 4.86 4.85 4.84 4.83 4.82 -40 - Temperature ( ° C) Output Voltage Temperature Coefficient -40 - Temperature ( ° C) Shutdown Current vs. Temperature ...

Page 5

... Io=100mA 1000 0 200 Line Transient Response SINGLE PULSE TEST T 1.0 Io=100mA 0.1 0.01 1000 1 2 Input-Output Differential Voltage (V) Operation in shaded area is not guaranteed 4-75 ZLDO485 V(in)=12V V(in)=7V Output Voltage Deviation 400 600 800 1000 Time ( s) =25 °C amb 0.1s 10ms Safe Operating Area ...

Page 6

... ZLDO485 APPLICATIONS 1). Operation From A Low Voltage Battery Pack Fig.1 shows the ZLDO485 regulator being used to stabilise the output battery pack. The ultra low dropout voltage of only 100mV at full load (300mA) given by the regulator allows the minimum number of cells to be used in the ...

Page 7

... ZSR500 Supply Input 0V Figure 3 is shutdown in this way, the quiescent current of the ZLDO485 falls to around 11 A. This makes the regulator suitable for a wide range of battery powered applications where intermittent operation occurs. The shutdown control pin should not be taken to a voltage higher than Vin if low quiescent supply current is important ...

Page 8

... The ZLDO485 provides an output called Low Battery Flag (LBF). Unlike many regulators that only signal that they are falling out of regulation, the LBF output of the ZLDO485 series indicates that the voltage drop across the regulator has fallen to less than typically 300mV and so supply failure is imminent. ...

Page 9

... CONNECTION DIAGRAM SM8 Package Suffix – T8 Top View – Pin 6 must be left floating SEE PIN DEFINITIONS ORDERING INFORMATION Part Number Package ZLDO485T8 SM8 Part Mark ZLDO485 4-79 ZLDO485 ...

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