L4988MDTR STMicroelectronics, L4988MDTR Datasheet - Page 16

• Manufacturer Part Number: L4988MDTR
• Description: IC REG LDO 5V 200MA 20SOIC
• Manufacturer: STMicroelectronics
• Series: -r

Specifications of L4988MDTR

• Regulator Topology: Positive Fixed
• Voltage - Output: 5V
• Voltage - Input: 5.6 ~ 31 V
• Voltage - Dropout (typical): 0.27V @ 200mA
• Number Of Regulators: 1
• Current - Output: 200mA
• Current - Limit (min): 200mA
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC
• Number Of Outputs: 1
• Polarity: Negative, Positive
• Output Voltage: - 0.3 V to + 6 V
• Output Type: Adjustable
• Dropout Voltage (max): 0.5 V at 200 mA
• Output Current: 200 mA
• Line Regulation: 25 mV
• Load Regulation: 25 mV
• Voltage Regulation Accuracy: 2 %
• Maximum Operating Temperature: + 150 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Reference Voltage: 5.1 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application information
3.2
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Reset
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:
Reset is active when En is high.
Figure 26. Reset timing diagram
Wi
Vo
Vcr
Res
Tosc = [(Vrhth-Vrlth) x Ctr] / Icr + [(Vrhth-Vrlth) x Ctr] / Idr
Icr:
Idr:
Vrhth, Vrlth:
Ctr:
trd = 512 x Tosc
<
trr
is an internally generated charge current
is an internally generated discharge current
are two voltages defined with the output voltage and a resistor output
divider
is an external capacitance.
trr
trd = 512 Tosc
Tosc
Vrhth
Vrlth
Vout_th
L4988