TLE4254
Electrical Characteristics
Data Sheet 8 Rev. 1.2, 2009-11-18
5 Electrical Characteristics
5.1 Tracking Regulator
The output voltage V
Q
is controlled by comparing it to the voltage applied at pin ADJ/EN and driving a PNP pass
transistor accordingly. The control loop stability depends on the output capacitor
C
Q
, the load current, the chip
temperature and the poles/zeros introduced by the integrated circuit and the load. To ensure stable operation, the
output capacitor’s capacitance and its equivalent series resistor ESR requirements given in the table “Functional
Range” have to be maintained. For details see also the typical performance graph “Output Capacitor Series
Resistor
ESR
CQ
vs. Output Current I
Q
”. Also, the output capacitor shall be sized to buffer load transients.
An input capacitor
C
I
is strongly recommended to buffer line influences. Connect the capacitors close to the IC
terminals.
Protection circuitry prevent the IC as well as the application from destruction in case of catastrophic events. These
safeguards contain output current limitation, reverse polarity protection as well as thermal shutdown in case of
overtemperature.
In order to avoid excessive power dissipation that could never be handled by the pass element and the package,
the maximum output current is decreased at high input voltages.
The overtemperature protection circuit prevents the IC from immediate destruction under fault conditions (e. g.
output continuously short-circuited) by reducing the output current. A thermal balance below 200 °C junction
temperature is established. Please note that a junction temperature above 150 °C is outside the maximum ratings
and reduces the IC lifetime.
The TLE4254 allows a negative supply voltage. However, several small currents are flowing into the IC increasing
its junction temperature. This has to be considered for the thermal design, respecting that the thermal protection
circuit is not operating during reverse polarity condition.
Table 1 Electrical Characteristics Tracking Regulator
V
I
= 13.5 V; V
ADJ/EN
≥ 2.0 V; V
FB
= V
Q
(version GA / EJ A); -40 °C ≤ T
j
≤ 150 °C; C
Q
= 1 µF;
all voltages with respect to ground (unless otherwise specified).
Pos. Parameter Symbol Limit Values Unit Test Condition
Min. Typ. Max.
5.1.1 Output Voltage Tracking
Accuracy
∆
V
Q
= V
EN/ADJ
- V
Q
∆V
Q
-5 – 5 mV
8 V ≤
V
I
≤ 18 V;
0.1 mA ≤
I
Q
≤ 60 mA;
V
ADJ/EN
= 5 V
5.1.2 -10 – 10 mV 5.5 V ≤
V
I
≤ 26 V;
0.1 mA ≤
I
Q
≤ 60 mA;
V
ADJ/EN
= 5 V
5.1.3 -10 – 10 mV 5.5 V ≤
V
I
≤ 32 V;
0.1 mA ≤
I
Q
≤ 30 mA;
V
ADJ/EN
= 5 V
5.1.4 Load Regulation
steady-state
|d
V
Q,load
|– 1 10 mV I
Q
= 0.1 mA to 70 mA;
V
ADJ/EN
= 5 V
5.1.5 Line Regulation
steady-state
|d
V
Q,line
|– 1 10 mV V
I
= 5.5 V to 32 V;
I
Q
= 5 mA
V
ADJ/EN
= 5 V
