Datasheet

Data Sheet 6 Rev. 1.01, 2009-10-19
IFX21401
Electrical Characteristics
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. 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 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 beyond the capability of 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. Please note that a junction temperature above
150 °C is outside the maximum ratings and reduces the IC lifetime.
The IFX21401 is protected from a reverse (i.e. negative polarity) input voltage. During reverse input voltage there
is a small of current flowing into the IC and thermal shutdown protection is not operating. For reverse current
details refer to the electrical characteristics table and typical performance graphs.
Table 1 Electrical Characteristics Tracking Regulator
V
I
= 13.5 V; V
ADJ/EN
≥ 2.5 V; -40 °C ≤ T
j
≤ 125 °C; all voltages with respect to ground (unless otherwise specified).
Pos. Parameter Symbol Limit Values Unit Conditions
Min. Typ. Max.
5.1.1 Output Voltage Tracking
Accuracy
Δ
V
Q
-5 – 5 mV 1 mA ≤ I
Q
≤ 10 mA;
6 V ≤
V
I
≤ 16 V
5.1.2 -25 – 25 mV 1 mA ≤
I
Q
≤ 50 mA;
6 V ≤
V
I
≤ 28 V
5.1.3 -25 – 25 mV 1 mA ≤
I
Q
≤ 10 mA;
6 V ≤
V
I
≤ 40V
5.1.4 Load Regulation
steady-state
|d
V
Q,load
|– – 15 mV I
Q
= 1 mA to 30 mA;
5.1.5 Line Regulation
steady-state
|d
V
Q,line
|– – 10 mV V
I
= 6 V to 40 V;
I
Q
= 10 mA
5.1.6 Power Supply Ripple
Rejection
PSRR
–48– dBf
ripple
= 100 Hz;
V
ripple
= 1 Vpp
1)
5.1.7 Dropout Voltage
V
dr
= V
I
- V
Q
V
dr
– 100 300 mV I
Q
= 10 mA
V
ADJ
≥ 4 V
2)
5.1.8 Output Current Limitation
I
Q,max
51 85 120 mA V
Q
= (V
ADJ
- 0.1 V)