NCP1573D ONSEMI [ON Semiconductor], NCP1573D Datasheet - Page 15

• Manufacturer Part Number: NCP1573D
• Description: Low Voltage Synchronous Buck Controller
• Manufacturer: ONSEMI [ON Semiconductor]

is very important in minimizing glitching because there is no
undervoltage lockout circuitry. For example, if the switcher
were powered up and regulating, and the supply began to
decrease slowly, the GATE outputs of the IC would continue
to switch until the driver circuitry ran out of headroom
(when V
collapse, an on−chip resistor from the GATE pins to ground
will bottom the external n−channel FETs and the switch
12 V V
Providing fast turn−on and turn−off edges to the IC power
COMP
V
OUT
CC
Figure 24. Output Transient with COMP Voltage
CC
reaches approximately 5 V). When the drivers
Positioned 100 mV Too High
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15
12 V V
node becomes disconnected from the DC−DC converter.
Until this happens, it is entirely possible that the bottom FET
may have a large duty cycle and be trying to discharge the
V
IC collapses, the reference voltage to the error amplifier may
change and result in false regulation. The circuit in Figure 23
will operate properly with turn−on and turn−off times on the
order of 500 μs or faster.
COMP
OUT
V
OUT
CC
Figure 25. Output Transient with COMP Voltage
capacitance. Additionally, as the bias circuitry in the
Positioned 100 mV Too Low