L9925 Просмотр технического описания (PDF) - STMicroelectronics
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L9925 Datasheet PDF : 9 Pages
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Figure 4. Application Diagram
L9925
CEN
100nF
D0
+5V
D0
D1
D2
40V
R0
10KΩ
I/O
I/O
I/O IN1
7V
CB
100nF
CB 40V
100µF
O EN1
7V
EN1
µP
1st FULL BRIDGE
T1 T2
O GND
O EN2
O IN3
O IN4
2nd FULL BRIDGE
T1 T2
CEN
100nF
R0
10KΩ
A
STEPPER MOTOR
B
OUT1
VS1 OUT2
CHARGE
PUMP
TEMP
T1
T2
EN1
5V
REGULATOR
EN2
CHARGE
PUMP
7V
EN1
40V
D99AT423
IN2
PGND1
VS2
OUT3
CEX
100nF
OUT4
PGND2 CEX
100nF
Figure 4 shows a typical application diagram for
DC motor driving. To assure the safety of the cir-
cuit in the reverse battery condition a reverse pro-
tetion diode D1 is necessary. The transient pro-
tection diode D2 must assure that themaximum
supply voltage VS during the transients at the
VBAT line will be limited to a value lower than the
absolute maximu ratings for VVSP. The capacities
CB are used to lower VS-EMR and its values de-
pend on the driving load.
The resistance feedback loop realized by Ro lim-
ited to the µP power supply line by the diode Do
allows open load detection. To protect the device
at the outputs against EMI or ESD > 2KV external
capacitors Cex may be used.
CIRCUIT DESCRIPTION
L9925 is a dual full bridge IC designed to drive
DC motors, stepper motors and other inductive
loads. Eah bridge has 4 power DMOS transistor
with RDSon = 0.75Ω and the relative protection
and control circuitry (see fig. 5). Tthe 4 half
bridges can be controlled independently by
means of the 4 inputs IN1, IN3, IN4 and 2 enable
inputs ENABLE1 and ENABLE2.
LOGIC DRIVE (true table for the two full bridges)
INPUTS
IN1 IN2
IN3 IN4
OUTPUT
MOSFETS
EN1 = EN2 = H L
L
H
H
@Tj > 150°C X
EN1 = EN2 = L X
L Sink 1, Sink2
H Sink1, Source2
L Source1, Sink2
H Source1, Source2
X All transistors turned OFF
X All transistors turned OFF
L = Low; H = High; X = Don’t care
CROSS CONDUCTION
The device guarantees the absence of cross-con-
duction by watching internal gate-source voltage
of the driving power DMOS.
TRANSISTOR OPERATION
ON STATE
When one of POWER DMOS transistors is ON it
can be considered as a resistor RDS(ON) = 0.75Ω
at a junction temperature of 25°C
5/9
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