ST L6235Q User Manual

DMOS driver for 3-phase brushless dc motor

Features

■ Operating supply voltage from 8 to 52 V

■ 5.6 A output peak current

■ R

■ Operating frequency up to 100 kHz

■ Non-dissipative overcurrent protection

■ Diagnostic output

■ Constant t

■ Slow decay synchronous rectification

■ 60° and 120° Hall effect decoding logic

■ Brake function

■ Tacho output for speed loop

■ Cross conduction protection

■ Thermal shutdown

■ Undervoltage lockout

■ Integrated fast freewheeling diodes

Figure 1. Block diagram

0.3 Ω typ. value @ TJ = 25 °C

DS(on)

PWM current controller

OFF

L6235Q

QFN-48

(7 x 7 mm)

Description

The L6235Q is a DMOS fully integrated 3-phase
motor driver with overcurrent protection. Realized
in BCDmultipower technology, the device
combines isolated DMOS power transistors with
CMOS and bipolar circuits on the same chip. The
device includes all the circuitry needed to drive a
3-phase BLDC motor including: a 3-phase DMOS
bridge, a constant OFF time PWM current
controller and the decoding logic for single ended
Hall sensors that generates the required
sequence for the power stage. Available in
QFN48 7x7 package, the L6235Q features a non­dissipative overcurrent protection on the high-side
power MOSFETs and thermal shutdown.

VBOOT V

VCP

DIAG

EN

BRAKE

FWD/REV

H

3

H

2

H

1

RCPULSE

TACHO

BOOT

CHARGE

TACHO

MONOSTABLE

10V 5V

REGULATOR

PUMP

OCD

VOLTAGE

THERMAL

PROTECTION

OCD1

OCD2

OCD

HALL-EFFECT

SENSORS

DECODING

LOGIC

OCD3

ONE SHOT

MONOSTABLE

GATE

LOGIC

PWM

MASKING

TIME

V

BOOT

OCD1

10V

V

BOOT

OCD2

10V

V

BOOT

OCD3

10V

COMPARATOR

SENSE

VS

A

OUT

1

OUT

2

SENSE

A

VS

B

OUT

3

SENSE

+

-

B

VREF

RCOFF

AM02555v1

November 2011 Doc ID 018997 Rev 2 1/33

www.st.com

33

Contents L6235Q

Contents

1 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.2 Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 Circuit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.1 Power stages and charge pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.2 Logic inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4.3 PWM current control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4.4 Slow decay mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.5 Decoding logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.6 Tacho . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.7 Non-dissipative overcurrent detection and protection . . . . . . . . . . . . . . . 18

4.8 Thermal protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

5 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6 Output current capability and IC power dissipation . . . . . . . . . . . . . . 25

7 Thermal management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

8 Electrical characteristics curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

9 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

10 Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

11 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2/33 Doc ID 018997 Rev 2

L6235Q Electrical data

1 Electrical data

1.1 Absolute maximum ratings

Table 1. Absolute maximum ratings

Symbol Parameter Parameter Value Unit

V

Supply voltage VSA = VSB = VS 60 V

S

V

OD

V

BOOT

V

IN,VEN

V

REF

V

RCOFF

V

SENSE

I

S(peak)

I

Differential voltage between
VSA, OUT1A, OUT2A, SENSEA and

, OUT1B, OUT2B, SENSE

VS

B

B

Bootstrap peak voltage VSA = VSB = VS V

Input and enable voltage range -0.3 to +7 V

Voltage range at pin V

Voltage range at pin RC

REF

OFF

Voltage range at pins SENSEA and
SENSE

B

Pulsed supply current (for each VSA

SB

pin)

and V

DC supply current (for each VSA and

S

VSB pin)

VSA = VSB = VS = 60 V;
VSENSEA = VSENSEB =

60 V

GND

+ 10 V

S

-0.3 to +7 V

-0.3 to +7 V

-1 to +4 V

V

= VSB = VS;

SA

< 1 ms

t

PULSE

VS

= VSB = VS 2.5 A

A

7.1 A

, TOP

T

stg

Storage and operating temperature
range

1.2 Recommended operating conditions

Table 2. Recommended operating conditions

Symbol Parameter Parameter Min. Max. Unit

V

Supply voltage VSA = VSB = VS 8 52 V

S

Differential voltage between

V

V

V

SENSE

I

OUT

f

OD

REF

T

sw

VSA, OUT1A, OUT2A, SENSEA and

, OUT1B, OUT2B, SENSEB

VS

B

Voltage range at pin V

-0.1 5 V

REF

Voltage range at pins SENSEA and
SENSE

B

DC output current VSA = VSB = VS;2.5 A

Operating junction temperature -25 +125 °C

j

Switching frequency 100 kHz

= VSB = VS;

VS

A

V

SENSEA

Pulsed tW < t

DC -1 1 V

= V

SENSEB

rr

-40 to 150 °C

52 V

-6 6 V

Doc ID 018997 Rev 2 3/33

Pin connection L6235Q

2 Pin connection

Figure 2. Pin connection (top view)

OUT1

OUT1

GND

TACHO

NC

NC

NC

NC

NC

NC

NC

NC

SENSEA

RCOFF

NC

48 47 46 45 44 43 42 41 40 39 38 37

1

EPAD

2

3

4

5

6

7

8

9

10

11

12

13 14 15 16 17 18 19 20 21 22 23 24

NC

SENSEB

RCPULSE

SENSEA

SENSEB

H1

H3

DIAG

EN

VREF

FWD/REV

Note: The exposed PAD must be connected to GND pin.

H2

BRAKE

VCP

VBOOT

OUT2

OUT3

OUT2

OUT3

NC

NC

36

NC

35

VSA

34

VSA

33

NC

32

NC

31

GND

30

NC

29

NC

28

NC

27

VSB

26

VSB

25

NC

AM02556v1

Table 3. Pin description

Pin Name Type Function

43 H1 Sensor input Single ended Hall effect sensor input 1.

44 DIAG

45, 46 SENSE

48 RC

OFF

Open drain

output

Power supply

A

RC pin

2, 3 OUT1 Power output Output 1

6, 31 GND GND Ground terminals.

12 TACHO

Open drain

output

13 RCPULSE RC pin

Overcurrent detection and thermal protection pin. An internal open
drain transistor pulls to GND when an overcurrent on one of the
high-side MOSFETs is detected or during thermal protection.

Half bridge 1 and half bridge 2 source pin. This pin must be
connected together with pin SENSEB to power ground through a
sensing power resistor.

RC network pin. A parallel RC network connected between this pin
and ground sets the current controller OFF time.

Frequency-to-voltage open drain output. Every pulse from pin H
shaped as a fixed and adjustable length pulse.

RC network pin. A parallel RC network connected between this pin
and ground sets the duration of the monostable pulse used for the
frequency-to-voltage converter.

is

1

4/33 Doc ID 018997 Rev 2

L6235Q Pin connection

Table 3. Pin description (continued)

Pin Name Type Function

Half bridge 3 source pin. This pin must be connected together with

15, 16 SENSE

Power supply

B

17 FWD/REV Logic input

pin SENSE
this pin also the inverting input of the sense comparator is
connected.

Selects the direction of the rotation. High logic level sets forward
operation, whereas low logic level sets reverse operation. If not
used, it must be connected to GND or +5 V.

to power ground through a sensing power resistor. At

A

18 EN Logic input

19 VREF Logic input

Chip enable. Low logic level switches off all power MOSFETs. If not
used, it must be connected to +5 V.

Current controller reference voltage. Do not leave this pin open or
connect to GND.

Brake input pin. Low logic level switches on all high-side power

20 BRAKE Logic input

MOSFETs, implementing the brake function. If not used, it must be
connected to +5 V.

21 VBOOT Supply voltage Bootstrap voltage needed for driving the upper power MOSFETs.

22, 23 OUT

26, 27 VSB Power supply

34, 35 VSA Power supply

38, 39 OUT

Power output Output 3.

3

Half bridge 3 power supply voltage. It must be connected to the
supply voltage together with pin VS

Half bridge 1 and half bridge 2 power supply voltage. It must be
connected to the supply voltage together with pin VS

Power output Output 2.

2

.

A

.

B

40 VCP Output Charge pump oscillator output.

41 H2 Sensor input Single ended Hall effect sensor input 2.

42 H

Sensor input Single ended Hall effect sensor input 3.

3

Doc ID 018997 Rev 2 5/33

Electrical characteristics L6235Q

3 Electrical characteristics

VS = 48 V, TA = 25 °C, unless otherwise specified.

Table 4. Electrical characteristics

Symbol Parameter Test condition Min. Typ. Max. Unit

V

Sth(ON)

V

Sth(OFF)

Turn-on threshold 6.6 7 7.4 V

Turn-off threshold 5.6 6 6.4 V

IS Quiescent supply current

Thermal shutdown temperature 165 °C

T

j(OFF)

Output DMOS transistors

High-side switch ON resistance

R

DS(ON)

Low-side switch ON resistance

I

DSS

Leakage current

Source drain diodes

V

Forward ON voltage ISD = 2.5 A, EN = low 1.15 1.3 V

SD

t

rr

t

fr

Reverse recovery time If = 2.5 A 300 ns

Forward recovery time 200 ns

Logic input (H1, H2, H3, EN, FWD/REV, BRAKE)

All bridges OFF; Tj = -25 °C to
125 °C

(1)

510mA

Tj = 25 °C 0.34 0.4

Tj =125 °C

(1)

0.53 0.59

Ω

Tj = 25 °C 0.28 0.34

Tj =125 °C

EN = low; OUT = V

(1)

0.47 0.53

2mA

S

EN = low; OUT = GND -0.15 mA

V

V

I

I

V

th(ON)

V

th(OFF)

V

th(HYS)

IH

IL

IH

Low level logic input voltage -0.3 0.8 V

IL

High level logic input voltage 2 7 V

Low level logic input current GND logic input voltage -10 µA

High level logic input current 7 V logic input voltage 10 µA

Turn-on input threshold 1.8 2.0 V

Turn-off input threshold 0.8 1.3 V

Input threshold hysteresis 0.25 0.5 V

Switching characteristics

t

D(on)EN

t

D(off)EN

t

D(on)IN

t

D(off)IN

Enable to out turn ON delay time

Enable to out turn OFF delay time

Other logic inputs to output turn
ON delay time

Other logic inputs to out turn OFF
delay time

(2)

(2)

I

I

I

I

=2.5 A, resistive load 100 250 400 ns

LOAD

=2.5 A, resistive load 300 550 800 ns

LOAD

=2.5 A, resistive load 2 ns

LOAD

=2.5 A, resistive load 2 ns

LOAD

6/33 Doc ID 018997 Rev 2

L6235Q Electrical characteristics

Table 4. Electrical characteristics (continued)

Symbol Parameter Test condition Min. Typ. Max. Unit

t

Output rise time

RISE

t

Output fall time

FAL L

Dead time protection 0.5 1 µs

t

DT

Charge pump frequency Tj = -25 °C to 125 °C (7) 0.6 1 MHz

f

CP

PWM comparator and monostable

(2)

(2)

I

I

=2.5 A, resistive load 40 250 ns

LOAD

=2.5 A, resistive load 40 250 ns

LOAD

I

RCOFF

V

offset

t

PROP

t

BLANK

t

ON(MIN)

t

OFF

I

BIAS

Source current at pin RC

OFF

Offset voltage on sense comparator V

Turn OFF propagation delay

Internal blanking time on SENSE
comparator

(3)

V

RCOFF =

REF

2.5 V 3.5 5.5 mA

= 0.5 V ±5 mV

Minimum ON time 1.5 2 µs

R

PWM recirculation time

Input bias current at pins VREF
VREF

B

and

A

OFF

= 100 kΩ; C

R

OFF

= 20 kΩ; C

= 1 nF 13 µs

OFF

= 1 nF 61 µs

OFF

Tacho monostable

I

RCPULSE

t

PULSE

R

TAC H O

Source current at pin RCPULSE V

Monostable of time

RCPULSE

R

PUL

R

PUL

Open drain ON resistance 40 60 Ω

= 2.5 V 3.5 5.5 mA

= 20 kΩ; C

= 100 kΩ; C

=1 nF 12 µs

PUL

=1 nF 60 µs

PUL

Over current detection e protection

I

sover

R

OPDR

I

OH

t

OCD(ON)

t

OCD(OFF)

1. Tested at 25 °C in a restricted range and guaranteed by characterization.

2. See Figure 3.

3. Measured applying a voltage of 1 V to pin SENSE and a voltage drop from 2 V to 0 V to pin V

4. See Figure 4.

Supply overcurrent protection
threshold

-25 °C<Tj <125 °C 4.0 5.6 7.1 A

Open drain ON resistance I = 4 mA 40 60 Ω

OCD high level leakage current V

OCD turn-on delay time

OCD turn-off delay time

(4)

(4)

= 5 V 1 µA

DIAG

I = 4 mA; CEN < 100 pF 200 ns

I = 4 mA; CEN < 100 pF 100 ns

REF

500 ns

1µs

10 µA

.

Doc ID 018997 Rev 2 7/33

Electrical characteristics L6235Q

Figure 3. Switching characteristic definition

EN

V

th(ON)

V

th(OFF)

t

I

OUT

90%

10%

D01IN1316

t

D(OFF)EN

t

FAL L

t

D(ON)EN

t

t

RISE

AM02557v1

Figure 4. Overcurrent detection timing definition

I

OUT

I

SOVER

ON

BRIDGE

OFF

V

DIAG

90%

10%

t

OCD(ON)

t

OCD(OFF)

AM02558v1

8/33 Doc ID 018997 Rev 2

L6235Q Circuit description

4 Circuit description

4.1 Power stages and charge pump

The L6235Q integrates a 3-phase bridge, which consists of 6 power MOSFETs connected
as shown in Figure 1, each power MOSFET has an R
with intrinsic fast freewheeling diode. Switching patterns are generated by the PWM current
controller and the Hall effect sensor decoding logic (Chapter 4.3 on page 11). Cross
conduction protection is implemented by using a dead time (t
internal timing circuit between the turn-off and turn-on of two power MOSFETs in one leg of
a bridge.

= 0.3 Ω (typical value @ 25 °C)

DS(ON)

= 1 µs typical value) set by

DT

Pins VS

and VSB must be connected together to the supply voltage (VS).

A

Using an N-channel power MOSFET for the upper transistors in the bridge requires a gate
drive voltage above the power supply voltage. The bootstrapped supply (V

) is obtained

BOOT

through an internal oscillator and a few external components to realize a charge pump
circuit, as shown in Figure 5. The oscillator output (pin VCP) is a square wave at 600 kHz
(typically) with 10 V amplitude. Recommended values/part numbers for the charge pump
circuit are shown in Tab le 5 .

Table 5. Charge pump external component values

Component Value

C

BOOT

C

P

R

P

220 nF

10 nF

100 Ω

D1 1N4148

D2 1N4148

Figure 5. Charge pump circuit

V

S

D1

R

C

VCP VBOOT VS

C

D2

P

P

BOOT

VS

A

B

AM02559v1

Doc ID 018997 Rev 2 9/33

Circuit description L6235Q

4.2 Logic inputs

Pins FWD/REV, BRAKE, EN, H1, H2 and H3 are TTL/CMOS and µC compatible logic
inputs. The internal structure is shown in Figure 6. Typical value for turn-on and turn-off
thresholds are respectively V

Pin EN (enable) may be used to implement overcurrent and thermal protection by
connecting it to the open collector DIAG output. If the protection and an external disable
function are both desired, the appropriate connection must be implemented. When the
external signal is from an open collector output, the circuit in Figure 7 may be used. For
external circuits that are push-pull outputs the circuit in Figure 8 may be used. The resistor
R

should be chosen in the range from 2.2 kΩ to 180 kΩ. Recommended values for REN

EN

and C

are respectively 100 kΩ and 5.6 nF. More information for selecting the values can

EN

be found in Section 4.7.

Figure 6. Logic inputs internal structure

=1.8 V and V

thon

PROTECTION

ESD

thoff

= 1.3 V.

5V

Figure 7. EN pins open collector driving

DIAG

OPEN

COLLECTOR

OUTPUT

5V

R

EN

C

EN

Figure 8. EN pins push-pull driving

R

PUSH-PULL

OUTPUT

EN

C

EN

AM02560v1

5V

EN

ESD

PROTECTION

AM02561v1

DIAG

5V

EN

ESD

PROTECTION

10/33 Doc ID 018997 Rev 2

AM02562v1