Manual

ManualsBrandsDiodes ManualsHardwareZLDO485

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 11µA.

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.

FEATURES

•

Very low dropout voltage

•

6mV dropout at 10mA output

•

30mV dropout at 100mA output

•

100mV dropout at 300mA output

•

4.85 volt fixed output

•

Other voltages available

•

Low quiescent current

•

1mA quiescent (typ) at 300mA output

•

Low battery flag

•

Shutdown control

•

Surface mount package

APPLICATIONS

•

Battery powered devices

•

Portable instruments

•

Portable communications

•

Laptop/Palmtop computers

•

Electronic organisers

4.85 VOLT ULTRA LOW DROPOUT

REGULATOR

ISSUE 2 - MAY 1997

LOW BATTERY

COMPARATOR

Low Battery Flag

Vin

OUTPUT

DRIVE

BIAS

CIRCUIT

SHUTDOWN

THERMAL

SHUTDOWN

Shutdown

Control

BANDGAP

REFERENCE

Shaping

Gnd

ZLDO485

4-71

Summary of content (9 pages)

PAGE 1
4.85 VOLT ULTRA LOW DROPOUT REGULATOR ZLDO485 ISSUE 2 - MAY 1997 DEVICE DESCRIPTION FEATURES • • • • • • • • • • • 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.
PAGE 2
ZLDO485 ABSOLUTE MAXIMUM RATING Input Supply Voltage Range Shutdown Input Voltage Range Low Battery Output Voltage Range Output Current Operating Temperature Storage Temperature Power Dissipation (Tamb=25°C) -0.3 to 20V -0.3 to Vin -0.3 to 20V 300mA -40 to 85°C -55 to 150°C 2W (Note 1) ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated) Tamb =25°C,IL=10mA,Cs=10pF,Cout =1µF Parameter SYMBOL CONDITIONS MIN. Output voltage Vo Vin=5.85V 4.
PAGE 3
ZLDO485 NOTES. 1. Maximum power dissipation of the device is calculated assuming the package is mounted on a PCB measuring 2 inches square. 2 Output voltage temperature coefficient is calculated as:- VO change x 1000000 VO x temperature change 3. Dropout voltage is defined as the input to output voltage differential at which the circuit ceases to regulate. The value is measured when the output voltage has dropped by 100mV from V out measured at the nominal input Vin = Vout + 1V 4. Guaranteed by design.
PAGE 4
ZLDO485 TYPICAL CHARACTERISTICS 1800 45 C(out)= 1µF C(out)= 1µF 40 Ripple Rejection (dB) Output Impedance (mΩ ) 1600 1400 1200 10pF 4.7pF 2.2pF 1000 800 600 400 35 10pF 4.7pF 2.2pF 30 25 20 15 10 200 5 0 100 1K 10K 100 100K 1K Output Impedance vs. Frequency 4.89 720 Io= 10mA V(in)= 7V V(in)= 7V 700 Quiescent Current (µA) Output Voltage (V) 100K Ripple Rejection vs. Frequency 4.88 4.87 4.86 4.85 4.84 4.83 680 660 640 620 600 580 560 540 -40 4.
PAGE 5
ZLDO485 TYPICAL CHARACTERISTICS 220 Output Voltage Deviation (V) V(in)=7V Dropout Voltage (mV) 200 180 160 140 120 85 °C 25 °C -40 °C 100 80 60 40 20 Io=100mA V(in)=12V V(in)=7V 1 Output Voltage Deviation 0 -1 0 0.1 1.0 10 1000 100 0 200 400 600 800 1000 Time (µs) Load Current (mA) Dropout Voltage vs. Load Current Line Transient Response SINGLE PULSE TEST Tamb =25 °C DC 1s 0.1s 10ms Io=100mA Load Current (A) Output Voltage Deviation (V) 1.0 V(in)=7V Io=0mA 0.
PAGE 6
ZLDO485 APPLICATIONS 1). Operation From A Low Voltage Battery Pack Fig.1 shows the ZLDO485 regulator being used to stabilise the output of a 6V 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 pack and also maximises the energy that can be removed from the battery before the output of the regulator starts to fail. ZLDO485 LBF Spg SC Gnd Vin D/C C1 10pF + 4.
PAGE 7
ZLDO485 APPLICATIONS output impedance of the switching power supply but no higher. The low dropout voltage of the ZLDO485 allows this circuit technique to be implemented very effectively, giving a highly stable and accurate low noise supply. 3). Logic Controlled Power Supply Fig.3 shows all that is necessary to allow a microprocessor to control a power supply based on the ZLDO485 The Shutdown Control pin (pin 2), is a logic compatible input that disables the regulator when a voltage in excess of 1.
PAGE 8
ZLDO485 APPLICATIONS 5). Low Battery Flag 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. This improved warning gives both more time for the system suppl ied to shutdown gracefully and maintains regulation while this happens.
PAGE 9
ZLDO485 CONNECTION DIAGRAM SM8 Package Suffix – T8 Top View – Pin 6 must be left floating SEE PIN DEFINITIONS ORDERING INFORMATION Part Number Package Part Mark ZLDO485T8 SM8 ZLDO485 4-79