STMICROELECTRONICS L9925

L9925

DMOS DUAL FULL BRIDGE DRIVER
2 INDEPENDENTLY CONTROLLED
H-BRIDGES
RDS,ON <0.9Ω @ Tamb = 25°C, VS = 14V
0.8A DC CURRENT WITHOUT HEAT SINK
LOW QUIESCENT MODE Iq <200µA
THEMAL PROTECTION
CROSS CONDUCTION PROTECTION
SUPPLY VOLTAGE UP TO 40V
CMOS COMPATIBLE INPUTS
OUTPUT SHORT-CIRCUIT PROTECTION
SO28
ORDERING NUMBER: L9925
DESCRIPTION
The L9925 is a dual full bridge driver for stepper
motor applications. Realized in BCD (Bipolar,
CMOS & DOS) techology, logic circuits, precise
linear blocks and power transistors are combined
to optimize circuit performance and minimize off
chip components. Schmitt triggers are used for all
input stages and are fully compatible with 5V
CMOS logic levels. When both enable signals are
low, the IC is commanded to a low quiescent current state and will draw less than 200µA from the
battery.
BLOCK DIAGRAM
OUT1
The charge pump is integrated on chip; no external components are required. Full performance is
maintaned for 9V <VS <16V. Extended ranges of
6V <<VS <9V and 16V <VS <40V yields full functionally but with relaxed performance. Over temperature protection and ESD protection to all pins
ensures relability and reduces system integration
failures.
VS1
OUT2
CHARGE
PUMP
CHARGE
PUMP
IN1
IN2
7V
7V
TEMP
EN1
EN1
7V
1st FULL BRIDGE
T1
EN1
T2
T1 T2
PGND1
EN1
5V
REGULATOR
GND
VS2
40V
T1 T2
EN2
EN2
OUT3
IN3
IN4
OUT4
2nd FULL BRIDGE
D99AT423
March 1999
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1/9
L9925
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are those values beyond whih damage to the device may occur. Functional
operation under these condition isn’t implied.
For voltages and currents applied externally to the device:
Symbol
Parameter
Value
Unit
-0.3 to 26
V
40
V
V VSDC
Dc Supply Voltage
VVSP
Supply Voltage Pulse (T ≤400ms)
IOUT
DC Output Load Current
±1.2
A
DC Output Current: for VOUT > VVS +0.3V or VOUT < -0.3V
the internal DMOS reverse and/or substrate diode become
conductive and the applied current should not exceed the
specified limit.
±1.8
A
DC Input Voltage
-0.3 to 7
V
Enable Input Voltage
-0.3 to 7
V
-40 to 150
°C
5
1.23
2
W
W
W
IOUT MAX
VIN1,2
V EN
Tstg, Tj
Ptot
(1)
Storage and Junction Temperature
Total Power Dissipation (Tpins = 80°C)
(T amb = 70°C no copper area on PCB)
2
(Tamb =70°C 8cm copper area on PCB)
(1) Device may be overstressed if pulsed simultaneous with short circuit at one or more of the outputs will be present.
PIN CONNECTION
PGND
1
28
N.C.
IN1
2
27
IN2
EN1
3
26
OUT2
N.C.
4
25
N.C.
N.C.
5
24
N.C.
OUT1
6
23
VS1
GND
7
22
GND
GND
8
21
GND
OUT3
9
20
VS2
N.C.
10
19
N.C.
N.C.
11
18
N.C.
EN2
12
17
OUT4
IN3
13
16
IN4
PGND
14
15
N.C.
D88AT424
THERMAL DATA
Symbol
(2)
Parameter
Unit
TjTS
Thermal Shut-down junction temperature min.
150
°C
TjTSH
Thermal Shut-down thereshold hysteresis typ.
25
°C
Rth j-amb
Thermal Resistance Junction-ambient
Rth j-pins
Thermal Resistance Junction-pins
With 6cm2 on board heat sink area
2/9
Value
(2)
50
°C/W
15
°C/W
L9925
PIN FUNCTIONS
N.
Name
1
PGND1
2
IN1
Function
Ground for DMOS sources in bridge 1
Digital Input from motor controller for bridge 1
3
EN1
Logic enable/disable for bridge 1 (active high)
4, 5
NC
No connect
6
OUT1
Output of one half of bridge 1
7, 8
GND
Ground
9
OUT3
Output of one half of bridge 2
10, 11
NC
No connect
12
EN2
Logic enable/disable for bridge 2 (active high)
13
IN3
Digital Input from motor controller for bridge 2
14
PGND2
15
NC
No connect
16
IN4
Digital Input from motor controller for bridge 2
17
OUT4
18, 19
NC
No connect
Ground for DMOS sources in bridge 2
Output of one half of bridge 2
20
VS2
Supply Voltage for bridge 2
21, 22
GND
Ground
23
VS1
Supply Voltage for bridge 1
24, 25
NC
No connect
26
OUT2
27
IN2
Digital Input from motor controller for bridge 1
28
NC
No connect
Output of one half of bridge 1
ELECTRICAL CHARACTERISTICS (VS = 9 to 16V; T j = -40 to 150°C (3) , unless otherwise specified.)
Symbol
IS
Parameter
Test Condition
Min.
Max.
Unit
200
µA
5
12
mA
0.75
0.8
Ω
1.9
Ω
EN1 = EN2 =0V; Tj = 85°C
Switch on Resistance
Tj = 25°C; VS = 14V; Io =300mA
Tj = 125°C; VS = 6V; Io =300mA
1.5
EN1 = EN2 =5V; Iload = 0A
R ds
Typ.
Quiescent Current
Td-on
Turn-on delay
See Fig 1
10
50
µs
Td-SB
Standby setting time
See Fig 1
50
200
µs
Td-off
Turn-off delay
See Fig 1
10
50
µs
trise
Output rise time (10 to 90%)
See Fig 1
0.5
5
20
µs
tfall
Output fall time (90 to 10%)
See Fig 1
0.5
5
20
µs
ILo
Output leakage current
EN = 0V; V o =VS or GND
-10
10
mA
INx, ENx
Logic Input Low voltage
-0.3
1.5
V
Ibias
Logic Input High voltage
3.5
Hysteresis
0.5
Input bias current
-50
1.0
6
V
2.0
V
300
µA
The voltage refered to GND and currents are assumed positive, when the current flows into the pin.
(3) Tested up to 125°C, parameter guaranted by correlation up to 150°C
3/9
L9925
Logic Levels
All inputs are positive, non inverting logic
Logic State
Voltage Range
0
-0.3 to 1.5V
1
3.5 to 6.0V
General Operation
With the bridge enabled, each input INx, maps directly to the corresponding output OUTx.
The output voltage will be equal to the difference
between the supply rail and the product of the
load current ad the on resistance of the output
switch.Vout = Vsupply - (RDS,ON ⋅ ILOAD).
Sourced load currents are positive.
Truth Table
Enable/ Disable
EN1
EN0
Bridge 1
Bridge 2
Iq
IN1
OUT1
IN2
OUT2
IN3
OUT3
IN4
OUT4
0
0
Disabled
Disabled
<200µA
0
0
0
0
0
0
0
0
0
1
Disabled
Enabled
<12mA
1
VS
1
VS
1
VS
1
VS
1
0
Enabled
Disabled
<12mA
1
1
Enabled
Enabled
<12mA
Figure 1. Timing Diagram
STANDBY MODE
OPERATING MODE
OVERTEMPERATURE
STANDBY MODE
EN2
EN1
IN1
IN2
tdON
t dSB
OUT1
t dOFF
t dSB
90%
Tristate
50%
Tristate
Tristate
Tristate
Tristate
10%
tr
t dSB
OUT2
tf
tdOFF
t dON
Tristate
tr
D99AT425
tf
Figure 2. Typical RON - Characteristics of Source
and Sink Stage
RON
(Ω)
t dSB
Figure 3. ON - Resistance vs Supply Voltage
RON
(Ω)
IOUT1/2=±0.3A
2
VVS=6V
VVS=12V
1.9
1.5
max for TJ ≤125°C
0.9
0.75
typ. for TJ =25°C
1
-40 -20
0
20
40
60
80 100 120 140 160 T(°C)
D99AT426
4/9
6
12
16.5
VVS(V)
D99AT427
L9925
Figure 4. Application Diagram
CEN
100nF
CEN
100nF
D0
D1
D2
40V
CB
100nF
STEPPER MOTOR
A
B
R0
10KΩ
CB 40V
100µF
+5V
OUT1
D0
VS1
OUT2
R0
10KΩ
I/O
CHARGE
PUMP
CHARGE
PUMP
I/O
I/O
IN1
IN2
7V
O
TEMP
7V
EN1
EN1
7V
T1
EN1
T2
µP
PGND1
1st FULL BRIDGE
O
T1 T2
GND
EN1
VS2
5V
REGULATOR
40V
O
EN2
O
IN3
O
IN4
T1 T2
OUT3
EN2
OUT4
CEX
100nF
PGND2
2nd FULL BRIDGE
CEX
100nF
D99AT423
Figure 4 shows a typical application diagram for
DC motor driving. To assure the safety of the circuit in the reverse battery condition a reverse protetion diode D1 is necessary. The transient protection 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 depend on the driving load.
The resistance feedback loop realized by Ro limited 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
OUTPUT
MOSFETS
IN1
IN3
IN2
IN4
EN1 = EN2 = H
L
L
H
H
L
H
L
H
Sink 1, Sink2
Sink1, Source2
Source1, Sink2
Source1, Source2
@Tj > 150°C
X
X
All transistors turned OFF
EN1 = EN2 = L
X
X
All transistors turned OFF
L = Low; H = High; X = Don’t care
CROSS CONDUCTION
The device guarantees the absence of cross-conduction 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
L9925
In this condition the dissipated power is ginen by:
PON = RDS(ON) ⋅ IDS2
The low RDS(ON) of the Multipower BCD process
can provide high currents with low power dissipation.
OFF STATE
When one of the POWER DMOS transistor is
OFF the VDS voltage is equal to the supply voltage and only the leakage current IDSS flows.
The power dissipation during this period is given
by:
POFF = VS ⋅ IDSS
Figure 5a. Two phase chopping
EN
TRANSITIONS
Like all MOS power transistors the DMOS
POWER transistors have an intrinsic diode between their source and drain that can operate as
a fast freewheeling diode in switched mode applications. During recirculation with the ENABLE input is low, the POWER MOS is OFF and the diode voltage it is clamped to its characteristics.
When the ENABLE input is low, the POWER
MOS is OFF and the diode carries all of the recirculation current. The power dissipated in the transitional times in the cycle depends upon the voltage and current waveforms in the application.
Ptrans = IDS(t) ⋅ VDS(t)
EN
IN2
IN1
IN1 = H
IN2 = L
EN1 = H
IN2
IN1
IN1 = L
IN2 = H
EN1 = H
D99AT429
D99AT430
Figure 5b. One phase chopping
EN
EN
IN2
IN1
IN1 = H
IN2 = L
EN1 = H
IN2
IN1
D99AT431
IN1 = H
IN2 = H
EN1 = H
D99AT432
Figure 5c. Enable chopping
EN
EN
IN2
IN1
IN1 = H
IN2 = L
EN1 = H
6/9
IN2
IN1
D99AT433
IN1 = X
IN2 = X
EN1 = L
D99AT434
L9925
THERMAL PROTECTION
A thermalprotection circuit has been included that
will disable the device if the junction temperature
reaches 150°C. When the temperature has fallen
to a safe level the device restarts under the control of the input and enable signals.
APPLICATION INFORMATION
RECIRCULATION
During recirculationwith the ENALBE input high,
the voltage drop across the transistor is RDS(ON).
for voltages less than 0.6V and is clamped at a
voltages depending on the characteristics of the
source-drain diode for greater voltages. Although
the device is protected against cross conduction.
POWER DISSIPATION each bridge
In order to achieve the high performance provided
by the L9925 some attention must be paid t ensure that it has an adequate PCB area to dissipate the heat. The forst stage of any thermal design is to calculate the dissipated power in the
application, for this example the half step operation shown in Fig. 6 is considered.
RISE TIME T R
When an arm of the half bridge is turned on current begins to flow in the inductive load until the
maximum current IL is reached after a time T R,
The dissipated energy EOFF/ ON.
EOFF/ON = [RDS(ON) ⋅ IL2 ⋅ TR] ⋅
2
3
Figure 6.
Tswitch
commutation ECOM. As two of the POWER DMOS
transistors are ON EON is given by:
EON = IL2 ⋅ RDS(ON) ⋅ 2 ⋅ TON
In the commutation the energy dissipated is:
ECON = VS ⋅ IL ⋅ TCOM ⋅ fSWITCH ⋅ TON
Where:
TCOM = Communication Time and it is assumed that:;
TCOM = trise = tfall ≤ 20µs
TSWITCH = Chopper frequency
FALL TIME TF
For this example it is assumed that the energy
dissipated in this part of the cycle takes the same
form as that shown for the rise time:
EOFF/ON = [RDS(ON) ⋅ IL2 ⋅ TF] ⋅
2
3
QUIESCENT ENERGY
The last contribution of the energy dissipation is
due to the quiescrent supply current and is given
by:
EQUIESCENT = IQUIESCENT ⋅ VS ⋅ T
TOTAL ENERGY PER CYCLE
ETOT = (2 ⋅ EOFF/ON + EON + ECOM) bridge1+
+ (2 ⋅ EOFF/ON + EON + ECOM) bridg2 + EQUIESCENT
The total power dissipation PDIS is simply:
IL
PDIS =
TR
TON
TF
TOFF
D99AT435
ON TIME TON
During this time the energy dissipated is due to
the ON resistance of the transistors EON and the
TR = Rise time
TON = ON time
TF = Fall time
TOFF = OFF time
T = Period
Etot
T
T = TR + TON + TF + TOFF
7/9
L9925
mm
DIM.
MIN.
TYP.
A
MAX.
MIN.
TYP.
2.65
MAX.
0.1
0.3
0.004
0.012
b
0.35
0.49
0.014
0.019
b1
0.23
0.32
0.009
0.013
0.5
c1
0.020
45° (typ.)
D
17.7
18.1
0.697
0.713
E
10
10.65
0.394
0.419
e
1.27
0.050
e3
16.51
0.65
F
7.4
7.6
0.291
0.299
L
0.4
1.27
0.016
0.050
S
OUTLINE AND
MECHANICAL DATA
0.104
a1
C
8/9
inch
8 ° (max.)
SO28
L9925
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of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is
granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are
subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products
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