L4952D View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L4952D' PDF : 8 Pages View PDF
L4952
is High the device is switched on. The diagnostic
circuitry detect the low drop voltage.
In this case the DIAG output is going low and can
mute the power output stage to avoid noise on
the loudspeaker.The two internal switches can
switch the stabilized output voltage with P-MOS
Transistors to one of the outputs 2 and 3 with low
drop. This is useful to switch the AM and FM cir-
Function of the external High side switch
driver
Fig 2 shows the principle circuitry of the external
High side switch. Fig. 3 shows the switch on/off
phase of the external High side switch. At the
time t0 the microcontroller switches on (curve 1 =
output signal of the microcontroller).
cuitry on or off.
The signal on the HSON pin of the L4952 is shown
To control it there are two digital inputs En2 and En3 on curve 2. At t1 the external Power pnp is
one for each switch. EN2 is High active and EN3 is switched on. At t2 (VHSON = VSON2) the internal
Low active. It’s possible to drive the AM/FM switch comparator compares the drop of the external pnp.
with one digital line (EN2 and EN3 together).
In case of normal operation the drop is smaller than
The driver for the external High side switch can VDth and no failure will be detected (curve 3).
switch on and off the external pnp transistor. The
drop detection circuitry avoid the damage of the
) external power pnp transistor.
t(s To supply the varicaps and the PLL-opamp of the
car radio a second very low drop 10 V regulator is
c available. This regulator in dropout has a typical
du resistance of 50Ω.
ro Typical Characteristics (Note 4)
P Figure 3: Stand by consumption versus
te temperature
In case of failure (that mean a higher drop than
VDth ) the external power pnp will be switched off
(curve 4). If an error is detected it will be stored in
the internal error flip-flop. The external pnp can
only be switched on again after having turned
HSON off (VHSON < VSON1) again.
Figure 4: Logic input currents versus input
voltage
lete Product(s) - Obsole Supply voltage rejection (C = 10µF, ESR = 4.7Ω,
Load at OUT4 = 10kΩ)
Obso Figure 5: Supply rejection versus Frequency.
OUT2 propagation delay (Load = 100Ω)
Figure 6: OUT2 propagation delay (Load = 100Ω)
5/8
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