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LT1158

1158fb

TYPICAL APPLICATION

DESCRIPTION

Half Bridge N-Channel

Power MOSFET Driver

A single input pin on the LT

1158 synchronously controls

two N-channel power MOSFETs in a totem pole conﬁ gura-

tion. Unique adaptive protection against shoot-through

currents eliminates all matching requirements for the two

MOSFETs. This greatly eases the design of high efﬁ ciency

motor control and switching regulator systems.

A continuous current limit loop in the LT1158 regulates

short-circuit current in the top power MOSFET. Higher

start-up currents are allowed as long as the MOSFET V

does not exceed 1.2V. By returning the FAULT output to

the enable input, the LT1158 will automatically shut down

in the event of a fault and retry when an internal pull-up

current has recharged the enable capacitor.

An on-chip charge pump is switched in when needed to

turn on the top N-channel MOSFET continuously. Special

circuitry ensures that the top side gate drive is safely

maintained in the transition between PWM and DC opera-

tion. The gate-to-source voltages are internally limited to

14.5V when operating at higher supply voltages.

L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other

trademarks are the property of their respective owners. Protected by U.S. Patents including

5365118.

Top and Bottom Gate Waveforms

FEATURES

APPLICATIONS

Drives Gate of Top Side MOSFET Above V

Operates at Supply Voltages from 5V to 30V

150ns Transition Times Driving 3000pF

Over 500mA Peak Driver Current

Adaptive Non-Overlap Gate Drives

Continuous Current Limit Protection

Auto Shutdown and Retry Capability

Internal Charge Pump for DC Operation

Built-In Gate Voltage Protection

Compatible with Current-Sensing MOSFETs

TTL/CMOS Input Levels

Fault Output Indication

PWM of High Current Inductive Loads

Half Bridge and Full Bridge Motor Control

Synchronous Step-Down Switching Regulators

Three-Phase Brushless Motor Drive

High Current Transducer Drivers

Battery-Operated Logic-Level MOSFETs

–

SENSE

0.015Ω

500μF

LOW

ESR

0.1μF

IRFZ34

24V

1N4148

10μF

1μF

0.01μF

PWM

0Hz TO

100kHz

BOOST

BOOST DR

T GATE DR

T GATE FB

T SOURCE

SENSE

–

B GATE DR

B GATE FB

GND

INPUT

ENABLE

FAULT

BIAS

LT1158

LOAD

LT1158 TA01

= 24V

= 12Ω

1158 TA02

Summary of content (22 pages)

PAGE 1
LT1158 Half Bridge N-Channel Power MOSFET Driver FEATURES n n n n n n n n n n n n DESCRIPTION Drives Gate of Top Side MOSFET Above V+ Operates at Supply Voltages from 5V to 30V 150ns Transition Times Driving 3000pF Over 500mA Peak Driver Current Adaptive Non-Overlap Gate Drives Continuous Current Limit Protection Auto Shutdown and Retry Capability Internal Charge Pump for DC Operation Built-In Gate Voltage Protection Compatible with Current-Sensing MOSFETs TTL/CMOS Input Levels Fault Output Indication A
PAGE 2
LT1158 ABSOLUTE MAXIMUM RATINGS (Note 1) Supply Voltage (Pins 2, 10) ......................................36V Boost Voltage (Pin 16) ..............................................56V Continuous Output Currents (Pins 1, 9, 15) .........100mA Sense Voltages (Pins 11, 12) .................. –5V to V+ + 5V Top Source Voltage (Pin 13) ................... –5V to V+ + 5V Boost to Source Voltage (V16 – V13) ........ –0.3V to 20V Operating Temperature Range LT1158C.................................................
PAGE 3
LT1158 ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. Test Circuit, V+ = V16 = 12V, V11 = V12 = V13 = 0V, Pins 1 and 4 open, Gate Feedback pins connected to Gate Drive pins unless otherwise speciﬁed. LT1158I SYMBOL I2 + I10 LT1158C PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX DC Supply Current (Note 2) V+ = 30V, V16 = 15V, V4 = 0.5V V+ = 30V, V16 = 15V, V6 = 0.
PAGE 4
LT1158 TYPICAL PERFORMANCE CHARACTERISTICS DC Supply Current 30 14 I2 + I10 + I16 V+ = 12V V13 = 0V 12 V13 = V+ SUPPLY CURRENT (mA) INPUT HIGH 10 INPUT LOW 8 6 4 ENABLE LOW 2 0 5 10 INPUT HIGH 10 8 INPUT LOW 6 4 ENABLE LOW 2 0 –50 –25 0 15 20 25 30 SUPPLY VOLTAGE (V) 35 40 50 25 75 0 TEMPERATURE (°C) Dynamic Supply Current 100 50% DUTY CYCLE V+ = 12V V+ = 6V 1 10 INPUT FREQUENCY (kHz) 100 LT1158 G03 Input Thresholds 2.
PAGE 5
LT1158 TYPICAL PERFORMANCE CHARACTERISTICS Current Limit Inhibit VDS Threshold Bottom Gate Rise Time 1.40 1.35 1.30 –40°C 1.25 +25°C 1.20 +85°C 1.15 1.10 400 350 350 300 CGATE = 10000pF 250 200 150 CGATE = 3000pF 100 CGATE = 1000pF 50 1.05 0 1.
PAGE 6
LT1158 PIN FUNCTIONS BOOST DR (Pin 1): Recharges and clamps the bootstrap capacitor to 14.5V higher than pin 13 via an external diode. V+ (Pin 2): Main supply pin; must be closely decoupled to the ground pin 7. BIAS (Pin 3): Decouple point for the internal 2.6V bias generator. Pin 3 cannot have any external DC loading. ENABLE (Pin 4): When left open, the LT1158 operates normally. Pulling pin 4 low holds both MOSFETs off regardless of the input state.
PAGE 7
LT1158 BLOCK DIAGRAM V+ V+ 16 BOOST CHG PUMP BOOST DR 1 15 T GATE DR V+ V+ 2 15V 14 T GATE FB LOGIC INPUT BIAS 3 – BIAS GEN T + 25μA 7.5V FAULT 1.75V + ENABLE 4 13 T SOURCE 2.7V – 1.2V 110mV 5 SENSE+ + 12 – 11 SENSE– S – O 2.6V + 7.5V 10 V+ 1-SHOT R INPUT 6 1.4V + – S R Q Q 15V 9 B GATE DR 1-SHOT R – B 1.
PAGE 8
LT1158 TEST CIRCUIT 150Ω 2W 1 2 + V+ + 10μF 0.01μF 3 4 + 5 V4 3k 1/2W V6 50Ω 6 7 8 BOOST DR BOOST + T GATE DR BIAS T GATE FB V ENABLE FAULT T SOURCE LT1158 INPUT GND B GATE FB 16 + 15 V16 14 2k 1/2W 3000pF + 13 V14 – V13 12 SENSE+ SENSE– V+ B GATE DR + VN2222LL 1μF CLOSED LOOP + 100Ω 11 V12 + 10 V11 9 3000pF + V8 LT1158 TC01 OPERATION (Refer to Functional Diagram) The LT1158 self-enables via an internal 25μA pull-up on the enable pin 4.
PAGE 9
LT1158 OPERATION (Refer to Functional Diagram) goes low in PWM operation, and is maintained by the charge pump when the top MOSFET is on DC. A regulated boost driver at pin 1 employs a source-referenced 15V clamp that prevents the bootstrap capacitor from overcharging regardless of V+ or output transients. The LT1158 provides a current-sense comparator and fault output circuit for protection of the top power MOSFET.
PAGE 10
LT1158 APPLICATIONS INFORMATION If individual gate decoupling resistors are used, the gate feedback pins can be connected to any one of the gates. Driving multiple MOSFETs in parallel may restrict the operating frequency at high supply voltages to prevent over-dissipation in the LT1158 (see Gate Charge and Driver Dissipation below). When the total gate capacitance exceeds 10,000pF on the top side, the bootstrap capacitor should be increased proportionally above 0.1μF.
PAGE 11
LT1158 APPLICATIONS INFORMATION Ugly Transient Issues In PWM applications the drain current of the top MOSFET is a square wave at the input frequency and duty cycle. To prevent large voltage transients at the top drain, a low ESR electrolytic capacitor must be used and returned to the power ground. The capacitor is generally in the range of 250μF to 5000μF and must be physically sized for the RMS current ﬂowing in the drain to prevent heating and premature failure.
PAGE 12
LT1158 APPLICATIONS INFORMATION Current Limit in Switching Regulator Applications 100 EFFICIENCY (%) 90 FIGURE 12 CIRCUIT VIN = 12V 80 70 60 0 0.5 1.0 1.5 2.0 2.5 3.0 OUTPUT CURRENT (A) 3.5 4.0 LT1158 F04 Figure 4. Typical Efﬁciency Curve for Step-Down Regulator with Synchronous Switch One fundamental difference in the operation of a stepdown regulator with synchronous switching is that it never becomes discontinuous at light loads.
PAGE 13
LT1158 APPLICATIONS INFORMATION Low Current Shutdown The LT1158 may be shutdown to a current level of 2mA by pulling the enable pin 4 low. In this state both the top and bottom MOSFETs are actively held off against any transients which might occur on the output during shutdown. This is important in applications such as 3-phase DC motor control when one of the phases is disabled while the other two are switching.
PAGE 14
LT1158 APPLICATIONS INFORMATION 5A/DIV of the LT1158 current limit loop, an initial current spike of from 2 to 5 times the ﬁnal value will be present for a few μs, followed by an interval in which IDS = 0. The current spike is normally well within the safe operating area (SOA) of the MOSFET, but can be further reduced with a small (0.5μH) inductor in series with the output.
PAGE 15
LT1158 APPLICATIONS INFORMATION Note that for the ﬁrst event only, tSHUTDOWN is approximately twice the above value since CEN is being discharged all the way from its quiescent voltage. Allowable values for RF are from zero to 10k. 7.5V 1.15V 25μA ENABLE CEN 1μF SENSE– pin is within 1.2V of supply. Under these conditions the current is limited only by the RDS(ON) in series with RSENSE. For a 5-lead MOSFET the current is limited by RDS(ON) alone, since RSENSE is not in the output path (see Figure 7).
PAGE 16
LT1158 APPLICATIONS INFORMATION from a true short. This is done by using the current limit to control cold ﬁlament current in conjunction with the selfprotection circuit of Figure 9. The reduced cold ﬁlament current also extends the life of the ﬁlament. down the top MOSFET. The LT1158 will then go into the automatic restart mode described in Self-Protection with Automatic Restart above.
PAGE 17
LT1158 TYPICAL APPLICATIONS DRIVER SUPPLY 10V TO 15V (CAN BE POWERED FROM VIN WITH LOGIC-LEVEL Q1, Q2) 0.33μF 16k 0.01μF + 10μF 1 8 2 7 LT1431 3 3.3k 1 2 200pF 6 3 4.99k 1% SHUTDOWN 4 5 1000pF 1 24k 6 8 470pF 7 2 CMOS 555 3 BOOST DR BOOST V+ T GATE DR 16 6 RX 1% 7 8 BIAS T GATE FB ENABLE T SOURCE LT1158 FAULT INPUT SENSE– 11 V+ 10 220μF 10V OS-CON s 4 Q1 0.22μF 500k L1 8μH 13 12 B GATE DR B GATE FB 14 SENSE+ GND + BAS16 15 0.01μF 5 4 VIN 4.
PAGE 18
LT1158 TYPICAL APPLICATIONS INPUT 30V MAX SHUTDOWN 4.7k 0.01μF 1N4148 4.7k 1μF 16 0.1μF *3.4k 1 + 1 15 2 2 + EXT SYNC 30k f = 25kHz 3 14 10μF 4 13 2.2nF 0.01μF 3 4 1N4148 BOOST DR V+ T GATE DR BIAS T GATE FB ENABLE T SOURCE LT3525 12 5 0.01μF 6 11 7 10 8 9 5 1N4148 6 BOOST LT1158 FAULT SENSE+ + 16 + 500μF EA LOW ESR IRFZ44 15 SHORT-CIRCUIT CURRENT = 15A 0.1μF 14 330k 13 L1 70μH RS 0.
PAGE 19
LT1158 TYPICAL APPLICATIONS 7.2V NOMINAL + BAT85 1 2 + 0.01μF 10μF STOP (FREE RUN) 3 1N4148 4 + 1k 1μF 5 6 PWM 7 8 BOOST DR BOOST V+ T GATE DR BIAS T GATE FB ENABLE T SOURCE FAULT INPUT LT1158 B GATE FB 15 15Ω 0.1μF 14 Q1 13 + 12 SENSE+ B GATE DR – 10 9 START CURRENT = 25A MINIMUM RS 0.015Ω 11 SENSE– V+ GND 100μF 16 15Ω Q2 - LT1158 F15 Q1, Q2: IRLZ44 (LOGIC-LEVEL) RS: DALE TYPE LVR-3 ULTRONIX RCS01 Figure 15.
PAGE 20
LT1158 TYPICAL APPLICATIONS 1N4148 1 BOOST DR 2 V 0.01μF 3 ENABLE A 4 + 10μF FAULT A 5 BOOST + T GATE DR BIAS T GATE FB ENABLE T SOURCE FAULT 6 INPUT A LT1158 INPUT 7 14 15Ω + Q1 D1 SIDE A: SHOWS STANDARD MOSFET CONNECTION 470μF LOW ESR 13 12 SENSE– 11 V+ 10 B GATE DR B GATE FB 0.1μF 15 SENSE+ GND 8 10V TO 30V 16 + RS 0.015Ω – 9 Q2 2.4k 15Ω 1N4148 1 2 BOOST DR BOOST V+ T GATE DR BIAS T GATE FB 15 0.
PAGE 21
LT1158 PACKAGE DESCRIPTION N Package 16-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510) .770* (19.558) MAX 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 .255 ± .015* (6.477 ± 0.381) .130 ± .005 (3.302 ± 0.127) .300 – .325 (7.620 – 8.255) .020 (0.508) MIN .008 – .015 (0.203 – 0.381) ( +.035 .325 –.015 +0.889 8.255 –0.381 .045 – .065 (1.143 – 1.651) .065 (1.651) TYP .120 (3.048) MIN ) .018 ± .003 (0.457 ± 0.076) .100 (2.54) BSC NOTE: 1.
PAGE 22
LT1158 TYPICAL APPLICATION 12V 1N4148 1 2 + 10μF 0.01μF 3 4 + 10μF 6.2k 5 6 ON/OFF 7 8 BOOST DR BOOST V+ T GATE DR BIAS T GATE FB ENABLE T SOURCE FAULT INPUT GND B GATE FB LT1158 1000μF IRCZ44 15 14 0.1μF + – 13 SENSE+ 12 SENSE– 11 V+ 10 B GATE DR + 16 12V 55W MBR330 51Ω 9 ISC: 10A tSHUTDOWN = 50ms tRESTART = 600ms LT1158 F18 Figure 18.