TLE4267 Datasheet, PDF (2/22 Pages) Siemens Semiconductor Group – 5-V Low-Drop Voltage Regulator

TLE 4267
Application
The IC regulates an input voltage V_I in the range of 5.5 V < V_I < 40 V to a nominal output
voltage of V_Q = 5.0 V. A reset signal is generated for an output voltage of V_Q < V_RT (typ.
4.5 V). The reset delay can be set with an external capacitor. The device has two logic
inputs. A voltage of V_E2 > 4.0 V given to the E2-pin (e.g. by ignition) turns the device on.
Depending on the voltage on pin E6 the IC may be hold in active-state even if V_E2 goes
to low level. This makes it simple to implement a self-holding circuit without external
components. When the device is turned off, the output voltage drops to 0 V and current
consumption tends towards 0 µA.
Design Notes for External Components
The input capacitor C_I is necessary for compensation of line influences. The resonant
circuit consisting of lead inductance and input capacitance can be damped by a resistor
of approx. 1 Ω in series with C_I. The output capacitor is necessary for the stability of the
regulating circuit. Stability is guaranteed at values of ≥ 22 µF and an ESR of ≤ 3 Ω within
the operating temperature range.
Circuit Description
The control amplifier compares a reference voltage, which is kept highly accurate by
resistance adjustment, to a voltage that is proportional to the output voltage and drives
the base of the series transistor via a buffer. Saturation control as a function of the load
current prevents any over-saturating of the power element.
The reset output RO is in high-state if the voltage on the delay capacitor C_D is greater or
equal V_UD. The delay capacitance C_D is charged with the current I_D for output voltages
greater than the reset threshold V_RT. If the output voltage gets lower than V_RT a fast
discharge of the delay capacitor C_D sets in and as soon as V_CD gets lower than V_LD the
reset output RO is set to low-level (see Figure 6). The reset delay can be set within wide
range by dimensioning the capacitance of the external capacitor.
Data Sheet
2
Rev. 2.5, 2007-03-20