Datasheet

L6235
8/25
CIRCUIT DESCRIPTION
POWER STAGES and CHARGE PUMP
The L6235 integrates a Three-Phase Bridge, which
consists of 6 Power MOSFETs connected as shown
on the Block Diagram. Each Power MOS has an
R
DS(ON)
= 0.3 Ω (typical value @25°C) with intrinsic
fast freewheeling diode. Switching patterns are gen-
erated by the PWM Current Controller and the Hall
Effect Sensor Decoding Logic (see relative para-
graphs). Cross conduction protection is implemented
by using a dead time (t
DT
= 1µs typical value) set by
internal timing circuit between the turn off and turn on
of two Power MOSFETs in one leg of a bridge.
Pins VS
A
and VS
B
MUST be connected together to
the supply voltage (V
S
).
Using N-Channel Power MOS for the upper transis-
tors in the bridge requires a gate drive voltage above
the power supply voltage. The Bootstrapped Supply
(V
BOOT
) is obtained through an internal oscillator and
few external components to realize a charge pump
circuit as shown in Figure 3. The oscillator output (pin
VCP) is a square wave at 600KHz (typically) with 10V
amplitude. Recommended values/part numbers for
the charge pump circuit are shown in Table1.
Table 1. Charge Pump External Component
Values.
Figure 3. Charge Pump Circuit
LOGIC INPUTS
Pins FWD/REV, BRAKE, EN, H
1
, H
2
and H
3
are TTL/
CMOS and µC compatible logic inputs. The internal
structure is shown in Figure 4. Typical value for turn-
ON and turn-OFF thresholds are respectively V
th(ON)
= 1.8V and V
th(OFF)
= 1.3V.
Pin EN (enable) may be used to implement Overcurrent
and Thermal protection by connecting it to the open col-
lector DIAG output If the protection and an external dis-
able function are both desired, the appropriate
connection must be implemented. When the external
signal is from an open collector output, the circuit in Fig-
ure 5 can be used . For external circuits that are push
pull outputs the circuit in Figure 6 could be used. The re-
sistor R
EN
should be chosen in the range from 2.2K Ω to
180K
Ω . Recommended values for R
EN
and C
EN
are re-
spectively 100K
Ω and 5.6nF. More information for se-
lecting the values can be found in the Overcurrent
Protection section.
Figure 4. Logic Input Internal Structure
Figure 5. Pin EN Open Collector Driving
Figure 6. Pin EN Push-Pull Driving
C
BOOT
220nF
C
P
10nF
R
P
100Ω
D
1
1N4148
D
2
1N4148
D2
C
BOOT
D1
R
P
C
P
V
S
VS
A
VCP VBOOT VS
B
D01IN1328
5V
D01IN1329
ESD
PROTECTION
5V
5V
OPEN
COLLECTOR
OUTPUT
R
EN
C
EN
EN
DIAG
D02IN137
8
ESD
PROTECTION
5V
PUSH-PULL
OUTPUT
R
EN
C
EN
EN
D02IN1379
DIAG
ESD
PROTECTION