RT9828 RICHTEK [Richtek Technology Corporation], RT9828 Datasheet - Page 6

• Manufacturer Part Number: RT9828
• Description: Dual Micro-Power Voltage Detectors
• Manufacturer: RICHTEK [Richtek Technology Corporation]

RT9828
Application Information
The RT9828 voltage detector monitors the input voltage fo
generate a reset signal while the input voltage is lower
then the detecting threshold voltage level.
The RESET pin is an open drain output. It is recommended
to connect a pull-up resister between RESET pin and V
Figure 1 shows the timming diagram of VDD and RESET
signals. When VDD is lower than V
low after a short delay time t
V
after the delay time t
t
Thermal Considerations
For continuous operation, do not exceed absolute
maximum operation junction temperature. The maximum
power dissipation depends on the thermal resistance of IC
package, PCB layout, the rate of surroundings airflow and
temperature difference between junction to ambient. The
maximum power dissipation can be calculated by following
formula :
P
Where T
temperature 125°C, T
θ
For recommended operating conditions specification of
RT9828, where T
temperature of the die (125°C) and T
ambient temperature. The junction to ambient thermal
resistance θ
www.richtek.com
6
RD
JA
TH
D(MAX)
and t
RESET
is the junction to ambient thermal resistance.
VDD
with a hystersis (V
= ( T
RP
J(MAX)
are showed in specification.
J(MAX)
t
RD
JA
Figure 1. Timming Diagram
is layout dependent. For SOT-23-6
is the maximum operation junction
− T
RP
J(MAX)
A
A
. The typical value of the delay time
is the ambient temperature and the
HYS
) / θ
), the RESET will be pulled up
JA
t
RP
is the maximum junction
RD
. When VDD is higher than
V
V
Minimum operation voltage
TH
TH
+ V
TH
, the RESET goes
HYS
A
is the maximum
IN
.
packages, the thermal resistance θ
standard JEDEC 51-3 single layer thermal test board. The
maximum power dissipation at T
by following formula :
P
SOT-23-6 packages
The maximum power dissipation depends on operating
ambient temperature for fixed T
θ
allows the designer to see the effect of rising ambient
temperature on the maximum power allowed.
JA
D(MAX)
. For RT9828 packages, the Figure 2 of derating curves
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Figure 2. Derating Curves for RT9828 Packages
0
= (125°C − 25°C) / (250°C/W) = 0.400W for
25
Ambient Temperature (°C)
50
SOT-23-6
J(MAX)
A
= 25°C can be calculated
DS9828-02 April 2011
75
and thermal resistance
JA
is 250°C/W on the
Single Layer PCB
100
125