
LV5044V
No.A0534-6/7
Pin Functions
Pin No.
Pin
Function
1
VDD
Gate drive power supply for the external low side MOSFETs. Connect this pin to VLIN5 through a filter.
2
LDRV1
Channel 1 external low side MOSFET gate drive.
This pin is also used as the signal input for short through prevention for the high and low side MOSFETs.
HDRV cannot be turned on unless this pin's voltage goes below 1V.
3
HDRV1
Channel 1 external high side MOSFET gate drive.
4
SW1
This pin is connected to the channel 1 switching node.
The external high side MOSFET source and the low side MOSFET drain are connected to this pin.This pin becomes the
return current route of pin HDRV. The drain of the discharging MOSFET used for the soft stop function is connected
internal in the IC (typ.15
). This pin is also used as the signal input for short through prevention for the high and low side
MOSFETs. LDRV cannot be turned on unless this pin's voltage goes below 1V referenced to PGND.
5
CBOOT1
Channel 1 bootstrap capacitor connection.
The high side MOSFET gate drive power is supplied from this pin. This pin is connected to VDD through a diode and to
SW1 through the bootstrap capacitor.
6
VLIN5
Internal 5V regulator output.
The current is supplied from VIN. The power supply for the IC internal control circuits is also supplied from this pin. A
bypass capacitor (6.8
F) is required between this pin and SGND. This pin is monitored by the UVLO function and the IC
starts operating when it first rises above 4.0V. (After starting, the IC will only stop if this voltage falls below 3.8V.)
7
COMP1
Channel 1 phase compensation.
The output of the internal transconductance amplifier is connected to this pin. The external phase compensation circuit
between this pin and SGND.
8
FB1
Channel 1 feedback input.
The transconductance amplifier inverting (
) input is connected to this pin. Provide the feedback potential to this pin by
voltage dividing the output voltage. The converter operates so that this pin goes to the internal reference voltage VREF,
0.8V. This pin is also monitored by both the UVP comparator and the OVP comparator. If this pin voltage falls to under
87% of the set voltage, the PGOOD1 pin will go low and the UV_TIMER will operate. If this pin voltage rises to over 117%
of the set voltage, the IC will latch in the off state.
9
RSNS1
Input for the channel 1 side overcurrent detection comparator and current detection amplifier. When resistor detection is
used, connect the low side of the current detection resistor inserted between VIN and the drain of the external high side
MOSFET to this pin. These connections must be wired independently so that the shared impedance with the main current
with respect to the detected voltage does not affect this circuit.
10
ILIM1
Connection to the channel 1 overcurrent detection trip point.
A 8.3
A (ILIM) sink constant-current supply is connected internal in the IC, and the overcurrent detection voltage ILIM ×
RLIM is generated by connecting the resistor RLIM between this pin and VIN. The voltage between VIN and ILIM is
compared to the voltage across the terminals of either the current detection resistor RSNS or the high side MOSFET to
detect the overcurrent state.
11
TD1
Channel 1 startup delay connection.
The time until the IC starts up after the power-on reset (POR) is cleared is set by the capacitor connected between this pin
and SGND. After the POR state is cleared, the external capacitor is charged by a 3.5
A constant current supplied
internally by the IC. The IC starts operation when the voltage on this pin exceeds 2.4V. The IC goes to the standby state
when the voltage on this pin is under 2.4V. If no external capacitor is connected to this pin, the IC will start as soon as the
power-on reset is cleared.
12
SS1
Channel 1 soft start capacitor connection.
After the power-on reset (POR) is cleared and the TD pin voltage exceeds 2.4V, this capacitor is charged by a 3.5
A
internal constant current supply from the SS1 pin. This pin is connected to the transconductance amplifier's noninverting
(
+) input, and the ramp waveform of the SS1 pin is reflected in the ramped-up output waveform. After the UV_DELAY time
out and the POR operates, this capacitor is discharged by the SS pin.
13
PGOOD1
Channel 1 power good pin.
An IC internal 28V MOSFET open drain is connected to this pin. This pin outputs a low level if the channel 1 output voltage
falls more than -13% relative to the set voltage. There is a hysteresis of about VREF × 1.5%.
14
UV_DELAY
Channel 1 and channel 2 common UVP delay connection.
The time until the IC switches off after the UVP state is detected is set by the capacitor connected between this pin and
SGND. If either the channel 1 or channel 2 output voltage falls under -80% of the set voltage, an IC internal 8.6
A
constant current source charges the external capacitor connected to this pin. When the voltage on this pin exceeds 2.4V,
the IC switches off. If no external capacitor is connected, the IC turns off immediately upon detection of the UVP state.
15
VIN
IC power supply.
16
CLKO
Clock output.
This pin outputs a clock signal synchronized with the CT pin oscillator waveform. When two or more LV5044V chips are
operated in synchronization, connect the CT pin of the slave device to the SLKO pin of the master device. If two or more
devices are operated in synchronization and the Td pin is used to change the startup timing between the devices, the
device that starts the soonest will be the master.
Continued on next page.