L4989MD STMicroelectronics, L4989MD Datasheet - Page 11

• Manufacturer Part Number: L4989MD
• Description: IC REG LDO 5V 150MA 20SOIC
• Manufacturer: STMicroelectronics

Specifications of L4989MD

• Regulator Topology: Positive Fixed
• Voltage - Output: 5V
• Voltage - Input: 5.6 ~ 31 V
• Voltage - Dropout (typical): 0.18V @ 150mA
• Number Of Regulators: 1
• Current - Output: 150mA
• Current - Limit (min): 170mA
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC
• Number Of Outputs: 1
• Polarity: Positive
• Input Voltage Max: 31 V
• Output Voltage: 5 V
• Output Type: Fixed
• Dropout Voltage (max): 0.4 V at 150 mA
• Output Current: 250 mA
• Line Regulation: 25 mV
• Load Regulation: 25 mV
• Voltage Regulation Accuracy: 3 %
• Maximum Operating Temperature: + 150 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

L4989
3
3.1
3.2
Voltage regulator
Reset
Application information
The voltage regulator uses a p-channel MOS transistor as a regulating element. With this
structure a very low dropout voltage at current up to 150mA is obtained. The output voltage
is regulated up to transient input supply voltage of 40V. No functional interruption due to
over-voltage pulses is generated.The voltage Regulator is always active and not depending
on the state of WEn input pin. A short circuit protection to GND is provided.
Figure 3.
The reset circuit supervises the output voltage Vo. The Vo_th reset threshold is defined with
the in-ternal reference voltage and a resistor output divider. If the output voltage becomes
lower than Vo_th then Res goes low with a reaction time trr. The reset low signal is
guaranteed for an output voltage Vo greater than 1V.
When the output voltage becomes higher than Vo_th then Res goes high with a delay trd.
This delay is obtained by an internal oscillator.
The oscillator period is given by:
where:
trd is given by:
The Reset is always active and not depending on the state of WEn input pin.
Tosc = [(Vrhth-Vrlth) x Ctr] / Icr + [(Vrhth-Vrlth) x Ctr] / Idr
Icr:
Idr:
Vrhth, Vrlth:
Ctr:
trd = 512 x Tosc
Behavior of output current versus regulated voltage Vo
is an internally generated charge current
divider
is an internally generated discharge current
are two voltages defined with the output voltage and a resistor output
is an external capacitance.
Vo_ref
Vo
Ishort Ilim
Iout
Application information
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