LM26003MH/NOPB National Semiconductor, LM26003MH/NOPB Datasheet - Page 12

• Manufacturer Part Number: LM26003MH/NOPB
• Description: IC REG BUCK LOW IQ 3A 20TSSOP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: Step-Down (Buck)r

Specifications of LM26003MH/NOPB

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.25 ~ 35 V
• Current - Output: 3A
• Frequency - Switching: 150kHz ~ 500kHz
• Voltage - Input: 4 ~ 38 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP Exposed Pad, 20-eTSSOP, 20-HTSSOP
• Power - Output: 3.1W
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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UVLO is sensed at both VIN and VDD, and is activated when
either voltage falls below 2.96V (typical). Although VDD is
typically less than 200 mV below VIN, it will not discharge
through VIN. Therefore when the VIN voltage drops rapidly,
VDD may remain high, especially in sleep mode. For fast line
FIGURE 6. Off-Pulse Skipping Waveforms
Vin = 3.5V, Vnom = 3.3V, fnom = 305 kHz
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voltage transients, using a larger capacitor at the VDD pin can
help to hold off a UVLO shutdown by extending the VDD dis-
charge time. By holding up VDD, a larger cap can also reduce
the R
ternately, under heavy loading the VDD voltage can fall sev-
eral hundred mV below VIN. In this case, UVLO may be
triggered by VDD even though the VIN voltage is above the
UVLO threshold.
When UVLO is activated the LM26003 enters a standby state
in which VDD remains charged. As input voltage and VDD
voltage rise above 3.99V (typical) the device will restart from
soft-start mode.
PGOOD
A power good pin, PGOOD, is available to monitor the output
voltage status. The pin is internally connected to an open
drain MOSFET, which remains open while the output voltage
is within operating range. PGOOD goes low (low impedance
to ground) when the output falls below 89% of nominal or EN
is pulled low. When the output voltage returns to within 95%
of nominal, as measured at the FB pin, PGOOD returns to a
high state. For improved noise immunity, there is a 5 µs delay
between the PGOOD threshold and the PGOOD pin going
low.
DS(ON)
(and dropout voltage) in low VIN conditions. Al-