XC9515AA01ZL TOREX [Torex Semiconductor], XC9515AA01ZL Datasheet - Page 11

• Manufacturer Part Number: XC9515AA01ZL
• Description: 2 channel Synchronous Step-Down DC/DC Converter with Manual Reset
• Manufacturer: TOREX [Torex Semiconductor]

■OPERATIONAL EXPLANATION (Continued)
<Thermal Shutdown>
For protecting the IC from heat damage, the thermal shutdown circuit monitors the chip temperature. When the chip
temperature reaches 150℃, the thermal shutdown circuit operates and the driver transistor will be set to OFF. As the chip
temperature drops to 130℃ by stopping current flow, the soft-start function operates to turn the output on.
<Short-Circuit Protection>
The short-circuit protection circuit monitors the FB voltage.
short-circuit protection circuit operates and turns the driver transistor off to latch when the FB voltage becomes less than half
of the setting voltage. Both two DC/DC blocks stop operations when either CH1 or CH2 of protection circuit is activated. At
this time, both Lx1 and Lx2 become high impedance. Once the IC is in latch mode, operations can be resumed by either
turning the IC off after letting both ends of EN1 and EN2 pins down to low level, or by restoring power. (The P_V
P_V
<Soft Start Function>
The soft-start circuit protects against inrush current, when the power is switched on, and also to protect against voltage
overshoot. It should be noted, however, that this circuit does not protect the load capacitor (C
the Vref voltage limited and depending upon the input to the error amps, the operation maintains a balance between the two
inputs of the error amps and controls the EXT1 pin's ON time so that it doesn't increase more than is necessary.
<UVLO Circuit>
When the V
forced OFF to prevent false pulse output caused by unstable operation of the internal circuitry. When the V
becomes 1.9V (TYP.) or higher (for XC9515A, 3.0V or lower), switching operation takes place. By releasing the UVLO
function, the IC performs the soft-start function to initiate output startup operation.
<Voltage Detector Block>
The series' detector function monitors the voltage divided by resistors connected to the P_V
voltage of the internal reference voltage source via the comparator. Because of hysteresis at the detector function, output at
the V
of the detect voltage). The output configuration of the V
required. The voltage detector block has a manual reset (MR) pin. By setting the MR pin at low level, the V
to be at low level.
By connecting a capacitor (Cd) to the Cd pin, the XC9515 series can set a delay time to V
releasing voltage. The delay time can be calculated from the internal resistance, Rdelay (2.5MΩ fixed TYP.) and the
value of Cd as per the following equation. As selecting the capacitor (Cd), the delay time can be set freely.
●Release Delay
DD2
D
OUT
voltages should be less than the low level of the EN1 and EN2 pins when restoring power.)
Delay Capacity Cd [μF]
pin will invert when the sense pin voltage of the detector block (P_V
IN
t
pin voltage becomes1.8V (TYP.) or lower (for XC9515A, 2.7V or lower), the P-channel output driver transistor is
DR
(Delay time) ＝Cd x Rdelay x 0.69
0.022
0.047
0.01
0.22
0.47
0.1
1
Release Delay t
1725
173
380
811
17
38
81
DR
D
OUT
(TYP.) [ms]
pin is N-channel open drain, therefore, a pull-up resistor is
If the output is shorted incorrectly with the ground, the
DD1
Release Delay t
) increases above the release voltage (105%
1035∼2415
487∼1135
DD1
103∼242
228∼532
DOUT
49∼113
10∼24
23∼53
DR
pin, as well as monitoring the
L
) from inrush current. With
(MIN.∼MAX.) [ms]
pin’s output signal when
Ta=25
D
OUT
IN
XC9515
pin is forced
pin voltage
o
C
11/21
Series
DD1
and