TB6558FLG
TOSHIBA BiCD Integrated Circuit Silicon Monolithic
TB6558FLG
DC Motor Driver
The TB6558FLG is a dual bridge driver IC for DC motor control
using LDMOS output transistors with low ON-resistance.
Four operation modes are selectable via IN1 and IN2: forward,
reverse, short brake and stop.
The TB6558FLG uses constant-current PWM chopper drive.
Features
•
•
•
•
•
•
•
•
•
•
Motor power supply voltage: V
M
≤
15 V (max)
Control power supply voltage: V
CC
=
2.7 V to 6 V
Output current: I
OUT
≤
0.8 A (max)
Low ON-resistance: 1.5
Ω
(upper and lower sum @ V
M
=
5 V (typ.))
Constant-current PWM chopper drive
Separate VrefA and VrefB pins allow the constant-current values to be individually programmed for each
channel.
Forward, reverse, short brake and stop
Thermal shutdown (TSD)
Small QON-24 package
Lead(Pb)-Free solderable
Weight: 0.05 g (typ.)
*:
This product has a MOS structure and is sensitive to electrostatic discharge. When handling this product, ensure
that the environment is protected against electrostatic discharge by using an earth strap, a conductive mat and an
ionizer. Ensure also that the ambient temperature and relative humidity are maintained at reasonable levels.
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2008-04-03
TB6558FLG
Block Diagram
V
CC
GND
STBY
AIN1
AIN2
V
refA
Control logic
(channel A)
Bridge driver
(channel A)
AO1
AO2
RFA
V
ref
+0.6
V
Band
gap
TSD
V
M
OSC
OSC
BIN1
BIN2
V
refB
20 kΩ
Control logic
(channel B)
Bridge driver
(channel B)
BO1
BO2
RFB
Pin Functions
Pin No.
14
5
15
11
9
19
18
21
1
22
24
3
6
8
12
13
4
Symbol
GND
OSC
V
refA
AIN1
AIN2
RFA
AO1
AO2
BO2
BO1
RFB
VM
BIN2
BIN1
V
refB
V
CC
STBY
Functional Description
Small signal ground
Internal oscillation frequency setting pin
Channel-A coil current setting pin
Control input 1 (channel A)
Control input 2 (channel A)
Coil current sense pin (channel A)
Output 1 (channel A)
Output 2 (channel A)
Output 2 (channel B)
Output 1 (channel B)
Coil current sense pin (channel B)
Motor power supply pin
Control input 2 (channel B)
Control input 1 (channel B)
Channel-B coil current setting pin
Small-signal power supply pin
Standby (power save) pin
V
M
(ope)
=
2.5 V to 13.5 V
Internal pull-down resistor of 200 kΩ
Internal pull-down resistor of 200 kΩ
An internal reference voltage generator (0.6 V typ.) is
connected to this pin. (The voltage divider ratio can be
determined by an external resistor.)
V
CC
(ope)
=
2.7 V to 5.5 V
H: Active (internal pull-down resistor of 300 kΩ)
Connection pin for the channel-A motor coil
Connection pin for the channel-A motor coil
Connection pin for the channel-B motor coil
Connection pin for the channel-B motor coil
Remarks
Ground for small-signal components powered by V
CC
Connection pin for an external capacitor used for reference
oscillation
This pin is externally controlled by using an external circuit.
Internal pull-down resistor of 200 kΩ
Internal pull-down resistor of 200 kΩ
Note: Pins 2, 7, 10, 16, 17, 20 and 23: No connect (NC)
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2008-04-03
TB6558FLG
Function Table
Input
IN1
H
L
H
L
H/L
IN2
H
H
L
L
H/L
STBY
H
H
H
H
L
OUT1
L
L
H
OUT2
L
H
L
Output
Drive Mode
Short brake
Reverse/forward
Forward/reverse
Stop
Standby (power save)
OFF (high impedance)
OFF (high impedance)
Functional Description
PWM Control
In PWM mode, the PWM chopper circuit alternates between on (t1, t5) and short brake (t3).
(To eliminate shoot-through current, a dead time (t2, t4) is inserted when the PWM is turned on and off.)
OUT1
M
OUT2
OUT1
M
OUT2
OUT1
M
OUT2
GND
<PWM: ON>
t1
<PWM: ON
→
OFF>
t2
GND
<PWM: OFF>
t3
GND
V
M
V
M
OUT1
M
OUT2
OUT1
M
OUT2
GND
<PWM: OFF
→
ON>
t4
<PWM: ON>
t5
GND
V
M
t1
Example:
Output voltage waveform (OUT1)
t3
t5
GND
t2
t4
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TB6558FLG
Oscillator Circuit Operational Description
The on-chip oscillation is controlled by the charging and discharging of an external capacitor C
OSC
.
V
CC
115
µA
ON when
charging
OSC
40 kΩ
20
µA
1.2 V
ON when
discharging
115
µA
C
OSC
Oscillator
20 kΩ
0.8 V
V
OSC
Waveform
In the above circuit, the charging and discharging rate (V
OSC
) of the external capacitor (C
OSC
) is
calculated as follows:
V
OSC
=
1
∫
i dt
C
OSC
Let the time at V
OSC
=
0.8 V be t1 and the time at V
OSC
=
1.2 V be t2, then the V
OSC
slope (∆V
OSC
) is
calculated as:
t
−
t
∆
V
OSC
= Ι ×
1 2
C
OSC
which can be rewritten as:
1
I
=
t1
−
t2
∆
V
OSC
⋅
C
OSC
The cycle period of the triangular wave oscillation is equal to the period of rise and fall times of V
OSC
slope,
which is, twice the time from t1 to t2.
Hence, f
OSC
can be expressed as a function of C
OSC
as follows:
f
OSC
=
1
I
=
2 (t1
−
t2)
+ ∆
t 2
⋅ ∆
V
OSC
⋅
C
OSC
+ ∆
t
In the above diagram,
∆V
OSC
=
|1.2 V
−
0.8 V|
=
0.4 V. Thus, f
OSC
can be calculated as:
f
OSC
=
1
1
=
3
2
×
0.4/115
µ
A
×
C
OSC
+ ∆
t 6.957
×
10
×
C
OSC
+ ∆
t
(∆t
=
350 ns (typ.): Turn-on time of a switching transistor)
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TB6558FLG
PWM Chopper Control
Turning on the power supply causes a current to flow into the motor coils. The peak current through the
winding is sensed via an external current-sense resistor. As the current increases, a voltage (VRF) develops
across the resistor, which is fed back to the comparator. At the predetermined reference voltage (V
limit
), the
comparator turns off (chops) the power supply.
When high-side output transistors are turned off, the TB6558FLG, by default, counts 10 rising edges of the
internal CK signal as turn-off period. (The counter resets at the 11
th
rising edge of CK.)
Based on this turn-off period, the TB6558FLG generates a PWM signal that turns on and off the output
transistors.
Timing Diagram of the PWM Chopper Circuit
CK
OSC
Internal clock
Off timer
10-bit counter
Generated
PWM signal
V
limit
1 2 3 4 5 6
(1 OSC cycle
=
1 CK cycle)
Counts 10 rising
edge of CK
Coil current
VRF
ON
OFF
ON
OFF
ON
Power on
(The upper limit of the coil current (IO peak) can be calculated as: IO
=
V
limit
/RNF.)
Power off
Other
The IN1 and IN2 input pins have a pull-down resistor of about 200 kΩ.
The STBY pin has a pull-down resistor of about 300 kΩ.
V
CC
Input
Pull-down
resistor
GND
5
2008-04-03
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