SA57003 Datasheet, PDF (12/16 Pages) NXP Semiconductors – Five-output composite voltage regulator

Philips Semiconductors
Five-output composite voltage regulator
Product data
SA57003
APPLICATION INFORMATION
ON/OFF₄
ON/OFF₅
ON/OFF₁
ON/OFF₃
ON/OFF₂
V_IN
C_IN
10 µF
1
16
2
15
3
14
4
13
SA57003
5
12
6
11
7
10
8
9
V_OUT1
V_OUT3
V_OUT5
V_OUT4
V_OUT2
C_NS1,2,3 (optional)
0.01 µF CERAMIC
C_OUT1,2,3,4,5
1.0 µF CERAMIC OR TANTALUM
SL01421
Figure 12. Typical application circuit.
Stability Factors: Capacitance and ESR
The operating stability of linear regulators is determined by start-up
delay, transient response to load currents, and stability of the
feedback loop. The SA57003 has a fast transient loop response,
with no built-in delay.
Keep in mind that the output capacitor tries to supply any
instantaneous increase in load current from its stored energy. Using
higher values of capacitance will enhance transient load
performance as well as stability. Lowering the ESR of the capacitors
will also improve the transient response to load current changes, but
it will decrease stability.
Power dissipation factors
The thermal performance of linear regulators depends on the
following parameters:
Maximum junction temperature (T_j) in °C
Maximum ambient temperature (T_amb) in °C
Power dissipation capability of the package in Watts (P_D)
Junction-to-ambient thermal resistance in °C/W
The Maximum Junction Temperature and Maximum Power
Dissipation are both determined by the manufacturer’s process and
device’s design. For the most part the ambient temperature is under
the control of the user. The Maximum Ambient Temperature
depends on the process used by the manufacturer. The package
type and manufacturer’s process determines Junction-to-Ambient
Thermal Resistance.
These parameters are related to each other as shown in the
following equation:
T_j = T_amb + ( P_D × R_th(j-a) )
The term ( P_D × R_th(j-a) ) represents the temperature rise from the
ambient to the internal junction of the device.
Power dissipation calculations
A regulator’s maximum power dissipation can be determined by
using the following equation:
P_D(max) = V_IN(max)I_G + [V_IN(max) – V_OUT(min)] I_OUT(max)
where:
V_IN(max) is the maximum input voltage
I_G is the maximum Ground Current at maximum output current
V_OUT(min) is the minimum output voltage
I_OUT(max) is the maximum output current
(V_IN(max)I_G) represents heat generated in the device due to internal
circuit biasing, leakage, etc. [V_IN(max) – V_OUT(min)] is the
input-to-output voltage drop across the device due to the I_OUT(max)
current. When multiplied by I_OUT(max), this represents heat
generated in the device due to the output load current.
Heat dissipation factors
The SA57003 device should not be operated under conditions that
would cause a junction temperature of 150 °C to be generated
because the thermal shutdown protection circuit will shut down the
device at or near this temperature.
Heat generated within the device is removed to the surrounding
environment by radiation or conduction along several paths. In
general, radiated heat is dissipated directly into the surrounding
ambient from the chip package and leads. Conducted heat flows
through an intermediate material, such as the leads or thermal
grease, to circuit board traces and heat sinks in direct contact with
the device’s package or leads. The circuit board then radiates this
heat to the ambient. For this reason, adequate airflow over the
device and the circuit board is important.
The TSSOP16 package is too small to easily use external heat sinks
to increase the surface area and enhance the dissipation of
2003 Oct 13
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