apu3073o APEC, apu3073o Datasheet - Page 4

• Manufacturer Part Number: apu3073o
• Description: Synchronous Pwm Controller With Over-current Protection / Ldo Controller
• Manufacturer: APEC

APU3073
PIN#
BLOCK DIAGRAM
12
13
14
15
16
POR
OCSet
SS/SD
Comp
3V
Fb1
Fb2
Vcc
V
P1
PIN SYMBOL
16
9
1
4
5
7
6
OCSet
PGnd
20uA
HDrv
Gnd
VcH
20uA
25K
25K
CS Comp
64uA
Max
This pin serves as the separate ground for MOSFET's driver and should be connected to
system's ground plane.
This pin serves as analog ground for internal reference and control circuitry. A high fre-
quency capacitor must be connected from Vcc pin to this pin for noise free operation.
Output driver for the high side power MOSFET. This pin should not go negative (below
ground), this may cause problem for the gate drive circuit. It can happen when the inductor
current goes negative (Source/Sink), soft-start at no load and for the fast load transient
from full load to no load. To prevent negative voltage at gate drive, a low forward voltage
drop diode might be connected between this pin and ground.
This pin is connected to a voltage that must be at least 4V higher than the bus voltage of
the switcher (assuming 5V threshold MOSFET) and powers the high side output driver. A
minimum of 1mF, high frequency capacitor must be connected from this pin to ground to
provide peak drive current capability.
This pin is connected to the Drain of the lower MOSFET via an external resister and it
provides the positive sensing for the internal current sensing circuitry. The external resis-
tor programs the current limit threshold depending on the R
An external capacitor can be placed in parallel with the programming resistor to provide
high frequency noise filtering.
3V
VcH
Vcc
PIN DESCRIPTION
Figure 2 - Simplified block diagram of the APU3073.
4.2V / 4.0V
3.5V / 3.3V
Error Amp
UVLO
Generator
Bias
0.8V
0.4V
Ct
Rt
FbLo Comp
Error Comp
POR
Oscillator
Vcc
1.25V
3V
En
TSD
Reset Dom
S
R
POR
Q
DS(ON)
1.25V
of the power MOSFET.
0.8V
14
11
12
13 Gnd
15
10
8
3
2
V
Rt
LDrv
PGnd
VcH
HDrv
VcL
Drv2
REF
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