View LT1158_75236.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

LT1158 Half Bridge N-Channel Power MOSFET Driver
FEATURES
s s s s s s s s s s s s
DESCRIPTION
A single input pin on the LT1158 synchronously controls two N-channel power MOSFETs in a totem pole configuration. Unique adaptive protection against shoot-through currents eliminates all matching requirements for the two MOSFETs. This greatly eases the design of high efficiency 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 VDS 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 operation. The gate-to-source voltages are internally limited to 14.5V when operating at higher supply voltages.
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
APPLICATIONS
s s s s s s
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
TYPICAL APPLICATION
24V 1N4148
BOOST DR
BOOST T GATE DR T GATE FB T SOURCE
0.1F IRFZ34
+
10F
V
+
+
500F LOW ESR
V+
PWM 0Hz TO 100kHz
INPUT LT1158
SENSE +
+
RSENSE 0.015 LOAD
+
1F
ENABLE FAULT BIAS
SENSE - B GATE DR B GATE FB GND
-
IRFZ34
0.01F
LT1158 TA01
U
U
U
Top and Bottom Gate Waveforms
VIN = 24V RL = 12
1158 TA02
1
LT1158 ABSOLUTE MAXIMUM RATINGS
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 ................................................ 0C to 70C LT1158I ............................................ -40C to 85C Junction Temperature (Note 1) LT1158C .......................................................... 125C LT1158I ........................................................... 150C Storage Temperature Range ................ -65C to 150C Lead Temperature (Soldering, 10 sec.)................ 300C
PACKAGE/ORDER INFORMATION
TOP VIEW BOOST DR V+ BIAS ENABLE FAULT INPUT GND B GATE FB 1 2 3 4 5 6 7 8 16 BOOST 15 T GATE DR 14 T GATE FB 13 T SOURCE 12 SENSE + 11 SENSE - 10 V + 9 B GATE DR
ORDER PART NUMBER LT1158CN LT1158IN
N PACKAGE 16-LEAD PLASTIC DIP JA = 70C/W
TOP VIEW BOOST DR 1 V+ 2 BIAS 3 ENABLE 4 FAULT 5 INPUT 6 GND 7 B GATE FB 8 16 BOOST 15 T GATE DR 14 T GATE FB 13 T SOURCE 12 SENSE + 11 SENSE - 10 V + 9 S PACKAGE 16-LEAD PLASTIC SOL B GATE DR
LT1158CS LT1158IS
JA = 110C/W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER I2 + I10 DC Supply Current (Note 2) CONDITIONS
Test Circuit, TA = 25C, V + = V16 = 12V, V11 = V12 = V13 = 0V, Pins 1 and 4 open, Gate Feedback pins connected to Gate Drive pins unless otherwise specified.
MIN 4.5 8
q
LT1158I TYP MAX 2.2 7 13 3 1.4 5 1.15 1.5 25 11 43 14.5 14.5 3 10 18 4.5 2 15 1.4 1.7 35 47 17 17
MIN 4.5 8 0.8 0.85 1.2 15 9 40 12 12
LT1158C TYP MAX 2.2 7 13 3 1.4 5 1.15 1.5 25 11 43 14.5 14.5 3 10 18 4.5 2 15 1.4 1.8 35 47 17 17
UNITS mA mA mA mA V A V V A V V V V
V = 30V, V16 = 15V, V4 = 0.5V V + = 30V, V16 = 15V, V6 = 0.8V V + = 30V, V16 = 15V, V6 = 2V V + = V13 = 30V, V16 = 45V, V6 = 0.8V
+
I16 V6 I6 V4 V4 I4 V15 V9 V1
Boost Current Input Threshold Input Current Enable Low Threshold Enable Hysteresis Enable Pullup Current Charge Pump Voltage Bottom Gate "ON" Voltage Boost Drive Voltage
0.8 0.9 1.3 15 9 40 12 12
V6 = 5V V6 = 0.8V, Monitor V9 V6 = 0.8V, Monitor V9 V4 = 0V V + = 5V, V6 = 2V, Pin 16 open, V13 5V V + = 30V, V6 = 2V, Pin16 open, V13 30V V + = V16 = 18V, V6 = 0.8V V = V16 = 18V, V6 = 0.8V, 100mA Pulsed Load
+
q q q q q q q q
2
U
W
U
U
WW
W
LT1158
ELECTRICAL CHARACTERISTICS
SYMBOL V8 I5 V5 PARAMETER Bottom Turn-Off Threshold Fault Output Leakage Fault Output Saturation CONDITIONS
Test Circuit, TA = 25C, V + = V16 = 12V, V11 = V12 = V13 = 0V, Pins 1 and 4 open, Gate Feedback pins connected to Gate Drive pins unless otherwise specified.
MIN 1 1
q
LT1158I TYP MAX 1.75 1.5 0.1 0.5 2.5 2 1 1 130 170 180 1.4 250 550 250 250 400 200
LT1158C MIN TYP MAX 1 1 1.75 1.5 0.1 0.5 85 120 120 1.1 110 150 1.25 130 350 120 130 200 100 2.5 2 1 1 135 180 180 1.4 250 550 250 250 400 200
UNITS V V A V mV mV mV V ns ns ns ns ns ns
V14 - V13 Top Turn-Off Threshold
V = V16 = 5V, V6 = 0.8V V + = V16 = 5V, V6 = 2V V + = 30V, V16 = 15V, V6 = 2V V = 30V, V16 = 15V, V6 = 2V, I5 = 10mA V + = 30V, V16 = 15V, V6 = 2V, I5 = 100A V + = 30V, V16 = 15V, V6 = 2V, Closed Loop
q
+
+
V12 - V11 Fault Conduction Threshold V12 - V11 Current Limit Threshold V12 - V11 Current Limit Inhibit VDS Threshold tR tD tF tR tD tF Top Gate Rise Time Top Gate Turn-Off Delay Top Gate Fall Time Bottom Gate Rise Time Bottom Gate Turn-Off Delay Bottom Gate Fall Time
90 130 120 1.1
q q q q q q
110 150 1.25 130 350 120 130 200 100
V + = V12 = 12V, V6 = 2V, Decrease V11 until V15 goes low Pin 6 (+) Transition, Meas. V15 - V13 (Note 3) Pin 6 (-) Transition, Meas. V15 - V13 (Note 3) Pin 6 (-) Transition, Meas. V15 - V13 (Note 3) Pin 6 (-) Transition, Meas. V9 (Note 3) Pin 6 (+) Transition, Meas. V9 (Note 3) Pin 6 (+) Transition, Meas. V9 (Note 3)
The q denotes specifications that apply over the full operating temperature range. Note 1: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formulas: LT1158IN, LT1158CN: TJ = TA + (PD x 70C/W) LT1158IS, LT1158CS: TJ = TA + (PD x 110C/W)
Note 2: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. See typical performance characteristics and applications information. Note 3: Gate rise times are measured from 2V to 10V, delay times are measured from the input transition to when the gate voltage has decreased to 10V, and fall times are measured from 10V to 2V.
TYPICAL PERFORMANCE CHARACTERISTICS
DC Supply Current
14 I2 + I10 + I16 12 INPUT HIGH
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
V13 = 0V 12 V13 = V + 10 8
10 INPUT LOW 8 6 4 2 0 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 35 40 ENABLE LOW
SUPPLY CURRENT (mA)
UW
LT1158 G01
DC Supply Current
14 I2 + I10 + I16 V + = 12V INPUT HIGH
30 25 20 15 10 5 0
Dynamic Supply Current (V +)
50% DUTY CYCLE CGATE = 3000pF
V + = 24V V + = 12V V + = 6V
INPUT LOW 6 4 2 0 -50 -25 ENABLE LOW
50 25 75 0 TEMPERATURE (C)
100
125
1
10 INPUT FREQUENCY (kHz)
100
LT1158 G03
LT1158 G02
3
LT1158
TYPICAL PERFORMANCE CHARACTERISTICS
Dynamic Supply Current
40 35 50% DUTY CYCLE V + = 12V
TOP GATE VOLTAGE (V)
INPUT THRESHOLD VOLTAGE (V)
SUPPLY CURRENT (mA)
30 25 20 15 10 5 0 1 10 INPUT FREQUENCY (kHz) 100
LT1158 G04
CGATE = 10000pF CGATE = 3000pF
CGATE = 1000pF
Enable Thresholds
3.5
FAULT CONDUCTION THRESHOLD (mV)
ENABLE THRESHOLD VOLTAGE (V)
3.0 2.5 2.0 1.5 1.0 0.5 0 0 5 10
V(HIGH)
-40C +25C +85C
140 130 120 110 100 90 80 70 60 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 35 40 +85C +25C -40C
CURRENT LIMIT THRESHOLD (mV)
-40C +25C V(LOW) +85C
15 20 25 30 SUPPLY VOLTAGE (V)
Current Limit Inhibit VDS Threshold
1.50
CURRENT LIMIT INHIBIT THRESHOLD (V)
1.45 1.40 1.35 1.30 1.25 1.20 1.15 1.10 1.05 1.00 0
V2 - V11
350 350
BOTTOM GATE FALL TIME (ns)
BOTTOM GATE RISE TIME (ns)
5
10 15 20 25 30 SUPPLY VOLTAGE (V)
4
UW
35 40
LT1158 G07
Charge Pump Output Voltage
50 45 40 35 30 25 20 15 10 5 0 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 35 40 10A LOAD NO LOAD
Input Thresholds
2.0 1.8 1.6 1.4 1.2 V(LOW) 1.0 0.8 0 5 V(HIGH) -40C +25C +85C -40C +25C +85C
10 15 20 25 30 SUPPLY VOLTAGE (V)
35
40
LT1158 G05
LT1158 G06
Fault Conduction Threshold
160 150 V11 = 0V 200 190 180 170 160 150 140 130 120 110 100
Current Limit Threshold
CLOSED LOOP
+85C +25C -40C
0
5
10 15 20 25 30 SUPPLY VOLTAGE (V)
35
40
LT1158 G08
LT1158 G09
Bottom Gate Rise Time
400 400
Bottom Gate Fall Time
300 250 200 150 100 50 CGATE = 1000pF CGATE = 3000pF CGATE = 10000pF
300 250 200 150 100 50 0
CGATE = 10000pF
-40C +25C +85C
CGATE = 3000pF
CGATE = 1000pF 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 35 40
35
40
0
0
5
10 15 20 25 30 SUPPLY VOLTAGE (V)
35
40
LT1158 G10
LT1158 G11
LT1158 G12
LT1158
TYPICAL PERFORMANCE CHARACTERISTICS
Top Gate Rise Time
400 350 400 350
TOP GATE RISE TIME (ns)
TOP GATE FALL TIME (ns)
CGATE = 10000pF
TRANSITION TIMES (ns)
300 250 200 150 100 50 0 0 5
CGATE = 10000pF
CGATE = 3000pF
CGATE = 1000pF
10 15 20 25 30 SUPPLY VOLTAGE (V)
PI FU CTIO S
Pin 1 (Boost Drive): Recharges and clamps the bootstrap capacitor to 14.5V higher than pin 13 via an external diode. Pin 2 (V +): Main supply pin; must be closely decoupled to the ground pin 7. Pin 3 (Bias): Decouple point for the internal 2.6V bias generator. Pin 3 cannot have any external DC loading. Pin 4 (Enable): When left open, the LT1158 operates normally. Pulling pin 4 low holds both MOSFETs off regardless of the input state. Pin 5 (Fault): Open collector NPN output which turns on when V12 - V11 exceeds the fault conduction threshold. Pin 6 (Input): Taking pin 6 high turns the top MOSFET on and bottom MOSFET off; pin 6 low reverses these states. An input latch captures each low state, ignoring an ensuing high until pin 13 has gone below 2.6V. Pin 8 (Bottom Gate Feedback): Must connect directly to the bottom power MOSFET gate. The top MOSFET turn-on is inhibited until pin 8 has discharged to 1.5V. A hold-on current source also feeds the bottom gate via pin 8. Pin 9 (Bottom Gate Drive): The high current drive point for the bottom MOSFET. When a gate resistor is used, it is inserted between pin 9 and the gate of the MOSFET. Pin 10 (V +): Bottom side driver supply; must be connected to the same supply as pin 2. Pin 11 (Sense Negative): The floating reference for the current limit comparator. Connects to the low side of a current shunt or Kelvin lead of a current-sensing MOSFET. When pin 11 is within 1.2V of V +, current limit is inhibited. Pin 12 (Sense Positive): Connects to the high side of the current shunt or sense lead of a current-sensing MOSFET. A built-in offset between pins 11 and 12 in conjunction with RSENSE sets the top MOSFET short-circuit current. Pin 13 (Top Source): Top side driver return; connects to MOSFET source and low side of the bootstrap capacitor. Pin 14 (Top Gate Feedback): Must connect directly to the top power MOSFET gate. The bottom MOSFET turn-on is inhibited until V14 - V13 has discharged to 1.75V. An onchip charge pump also feeds the top gate via pin 14. Pin 15 (Top Gate Drive): The high current drive point for the top MOSFET. When a gate resistor is used, it is inserted between pin 15 and the gate of the MOSFET. Pin 16 (Boost): Top side driver supply; connects to the high side of the bootstrap capacitor and to a diode either from supply (V + < 10V) or from pin 1 (V + > 10V).
UW
35 40
LT1158 G13
Top Gate Fall Time
800 700 600 500 400
Transition Times vs RGate
V + = 12V CGATE = 3000pF
300 250 200 150 100
RISE TIME FALL TIME
CGATE = 3000pF
300 200 100
CGATE = 1000pF 50 0 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 35 40
0
0
10 20 30 40 50 60 70 80 90 100 GATE RESISTANCE ()
LT1158 G15
LT1158 G14
U
U
U
5
LT1158
FUNCTIONAL DIAGRA W
V+ 16 BOOST CHG PUMP BOOST DR 1 V+ 2 V+ 15V 14 T GATE FB BIAS 3 BIAS GEN LOGIC INPUT T 25A 1.75V ENABLE 4 7.5V 15 T GATE DR O 1-SHOT R INPUT 6 1.4V 1-SHOT R B GND 7
+
2.7V - 1.2V 110mV
FAULT
5 S
7.5V 10 V +
+ -
S
Q Q 15V 9 B GATE DR
R
6
-
+
-
+
-
+
U
U
V+
13 T SOURCE
+ -
12
SENSE+
11 SENSE-
2.6V
1.5V
8 B GATE FB
1158 FD
LT1158
TEST CIRCUIT
150 2W 1 2 BOOST DR V
+
BOOST T GATE DR T GATE FB T SOURCE LT1158
16
+
15 14 13 1F
VN2222LL
+
V16
+
V+
+
10F
0.01F 3 4
BIAS ENABLE FAULT INPUT GND B GATE FB
+
V14 - V13
3000pF
2k 1/2W
+
V4 3k 1/2W V6 50
5 6 7 8
12 SENSE+ SENSE - V
+
CLOSED LOOP 100
11 10 9
+
V12
+
V11
B GATE DR
3000pF
+
V8
LT1158 TC01
OPERATIO
The LT1158 self-enables via an internal 25A pull-up on the enable pin 4. When pin 4 is pulled down, much of the input logic is disabled, reducing supply current to 2mA. With pin 4 low, the input state is ignored and both MOSFET gates are actively held low. With pin 4 enabled, one or the other of the 2 MOSFETs is turned on, depending on the state of the input pin 6: high for top side on, and low for bottom side on. The 1.4V input threshold is regulated and has 200mV of hysteresis. In order to allow operation over 5V to 30V nominal supply voltages, an internal bias generator is employed to furnish constant bias voltages and currents. The bias generator is decoupled at pin 3 to eliminate any effects from switching transients. No DC loading is allowed on pin 3. The top and bottom gate drivers in the LT1158 each utilize two gate connections: 1) A gate drive pin, which provides the turn-on and turn-off currents through an optional series gate resistor; and 2) A gate feedback pin which connects directly to the gate to monitor the gate-to-source voltage and supply the DC gate sustaining current.
U
(Refer to Functional Diagram)
Whenever there is an input transition on pin 6, the LT1158 follows a logical sequence to turn off one MOSFET and turn on the other. First, turn-off is initiated, then VGS is monitored until it has decreased below the turn-off threshold, and finally the other gate is turned on. An input latch gets reset by every low state at pin 6, but can only be set if the top source pin has gone low, indicating that there will be sufficient charge in the bootstrap capacitor to safely turn on the top MOSFET. In order to conserve power, the gate drivers only provide turn-on current for up to 2s, set by internal one-shot circuits. Each LT1158 driver can deliver 500mA for 2s, or 1000nC of gate charge -- more than enough to turn on multiple MOSFETs in parallel. Once turned on, each gate is held high by a DC gate sustaining current: the bottom gate by a 100A current source, and the top gate by an on-chip charge pump running at approximately 500kHz. The floating supply for the top side driver is provided by a bootstrap capacitor between the boost pin 16 and top source pin 13. This capacitor is recharged each time pin
7
LT1158
OPERATIO
13 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.
APPLICATIONS INFORMATION
Power MOSFET Selection Since the LT1158 inherently protects the top and bottom MOSFETs from simultaneous conduction, there are no size or matching constraints. Therefore selection can be made based on the operating voltage and RDS(ON) requirements. The MOSFET BVDSS should be at least 2 x VSUPPLY, and should be increased to 3 x VSUPPLY in harsh environments with frequent fault conditions. For the LT1158 maximum operating supply of 30V, the MOSFET BVDSS should be from 60V to 100V. The MOSFET RDS(ON) is specified at TJ = 25C and is generally chosen based on the operating efficiency required as long as the maximum MOSFET junction temperature is not exceeded. The dissipation in each MOSFET is given by: P = D IDS the MOSFET junction temperature will be 125C, and = 0.007(125 - 25) = 0.7. This means that the required RDS(ON) of the MOSFET will be 0.089/1.7 = 0.0523, which can be satisfied by an IRFZ34. Note that these calculations are for the continuous operating condition; power MOSFETs can sustain far higher dissipations during transients. Additional RDS(ON) constraints are discussed under Starting High In-Rush Current Loads. Paralleling MOSFETs
( )( )
2
1 + RDS(ON)
where D is the duty cycle and is the increase in RDS(ON) at the anticipated MOSFET junction temperature. From this equation the required RDS(ON) can be derived:
RDS(ON) =
P D IDS
( ) (1+ )
2
For example, if the MOSFET loss is to be limited to 2W when operating at 5A and a 90% duty cycle, the required RDS(ON) would be 0.089/(1 + ). (1 + ) is given for each MOSFET in the form of a normalized RDS(ON) vs. temperature curve, but = 0.007/C can be used as an approximation for low voltage MOSFETs. Thus if TA = 85C and the available heat sinking has a thermal resistance of 20C/W,
8
U
W
U
U
U
(Refer to Functional Diagram)
The comparator input pins 11 and 12 are normally connected across a shunt in the source of the top power MOSFET (or to a current-sensing MOSFET). When pin 11 is more than 1.2V below V + and V12 - V11 exceeds the 110mV offset, fault pin 5 begins to sink current. During a short circuit, the feedback loop regulates V12 - V11 to 150mV, thereby limiting the top MOSFET current.
GATE DR LT1158 GATE FB RG RG
RG: OPTIONAL 10
1158 F01
Figure 1. Paralleling MOSFETs
When the above calculations result in a lower RDS(ON) than is economically feasible with a single MOSFET, two or more MOSFETs can be paralleled. The MOSFETs will inherently share the currents according to their RDS(ON) ratio. The LT1158 top and bottom drivers can each drive four power MOSFETs in parallel with only a small loss in switching speeds (see Typical Performance Characteristics). Individual gate resistors may be required to "decouple" each MOSFET from its neighbors to prevent
LT1158
APPLICATIONS INFORMATION
high frequency oscillations -- consult manufacturer's recommendations. 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 0.1F. Gate Charge and Driver Dissipation A useful indicator of the load presented to the driver by a power MOSFET is the total gate charge QG, which includes the additional charge required by the gate-to-drain swing. QG is usually specified for VGS = 10V and VDS = 0.8VDS(MAX). When the supply current is measured in a switching application, it will be larger than given by the DC electrical characteristics because of the additional supply current associated with sourcing the MOSFET gate charge: MOSFET Gate Drive Protection For supply voltages of over 8V, the LT1158 will protect standard N-channel MOSFETs from under or overvoltage gate drive conditions for any input duty cycle including DC. Gate-to-source zener clamps are not required and not recommended since they can reduce operating efficiency. A discontinuity in tracking between the output pulse width and input pulse width may be noted as the top side MOSFET approaches 100% duty cycle. As the input low signal becomes narrower, it may become shorter than the time required to recharge the bootstrap capacitor to a safe voltage for the top side driver. Below this duty cycle the output pulse width will stop tracking the input until the input low signal is <100ns, at which point the output will jump to the DC condition of top MOSFET "on" and bottom MOSFET "off." Low Voltage Operation The LT1158 can operate from 5V supplies (4.5V min.) and in 6V battery-powered applications by using logic-level N-channel power MOSFETs. These MOSFETs have 2V maximum threshold voltages and guaranteed RDS(ON) limits at VGS = 4V. The switching speed of the LT1158, unlike CMOS drivers, does not degrade at low supply voltages. For operation down to 4.5V, the boost pin should be connected as shown in Figure 2 to maximize gate drive to the top side MOSFET. Supply voltages over 10V should not be used with logic-level MOSFETs because of their lower maximum gate-to-source voltage rating.
5V N.C. BOOST DR BOOST T GATE DR LT1158 T GATE FB T SOURCE D1: LOW-LEAKAGE SCHOTTKY BAT85 OR EQUIVALENT D1
dQ dQ ISUPPLY = IDC + G + G dt TOP dt BOTTOM
The actual increase in supply current is slightly higher due to LT1158 switching losses and the fact that the gates are being charged to more than 10V. Supply current vs. switching frequency is given in the Typical Performance Characteristics. The LT1158 junction temperature can be estimated by using the equations given in Note 1 of the electrical characteristics. For example, the LT1158SI is limited to less than 25mA from a 24V supply: TJ = 85C + (25mA x 24V x 110C/W) = 151C exceeds absolute maximum In order to prevent the maximum junction temperature from being exceeded, the LT1158 supply current must be checked with the actual MOSFETs operating at the maximum switching frequency.
U
W
U
U
+
0.1F LOGIC-LEVEL MOSFET
LT1158 F02
Figure 2. Low Voltage Operation
9
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 250F to 5000F and must be physically sized for the RMS current flowing in the drain to prevent heating and premature failure. In addition, the LT1158 requires a separate 10F capacitor connected closely between pins 2 and 7. The LT1158 top source and sense pins are internally protected against transients below ground and above supply. However, the gate drive pins cannot be forced below ground. In most applications, negative transients coupled from the source to the gate of the top MOSFET do not cause any problems. However, in some high current (10A and above) motor control applications, negative transients on the top gate drive may cause early tripping of the current limit. A small Schottky diode (BAT85) from pin 15 to ground avoids this problem. Switching Regulator Applications The LT1158 is ideal as a synchronous switch driver to improve the efficiency of step-down (buck) switching regulators. Most step-down regulators use a high current Schottky diode to conduct the inductor current when the switch is off. The fractions of the oscillator period that the switch is on (switch conducting) and off (diode conducting) are given by:
LT1158
FAULT REF PWM INPUT
Figure 3. Adding Synchronous Switching to a Step-Down Switching Regulator
10
U
W
U
U
V SWITCH "ON" = OUT x TOTAL PERIOD VIN V -V SWITCH "OFF" = IN OUT x TOTAL PERIOD VIN
Note that for VIN > 2VOUT, the switch is off longer than it is on, making the diode losses more significant than the switch. The worst case for the diode is during a short circuit, when VOUT approaches zero and the diode conducts the short-circuit current almost continuosly. Figure 3 shows the LT1158 used to synchronously drive a pair of power MOSFETs in a step-down regulator application, where the top MOSFET is the switch and the bottom MOSFET replaces the Schottky diode. Since both conduction paths have low losses, this approach can result in very high efficiency -- from 90% to 95% in most applications. And for regulators under 5A, using low RDS(ON) N-channel MOSFETs eliminates the need for heatsinks.
VIN
+
T GATE DR T GATE FB RGS T SOURCE SENSE + RSENSE VOUT
+
SENSE - B GATE DR B GATE FB
1158 F03
LT1158
APPLICATIONS INFORMATION
100
90 EFFICIENCY (%) 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. The inductor current doesn't stop ramping down when it reaches zero, but actually reverses polarity resulting in a constant ripple current independent of load. This does not cause any efficiency loss as might be expected, since the negative inductor current is returned to VIN when the switch turns back on. The LT1158 performs the synchronous MOSFET drive and current sense functions in a step-down switching regulator. A reference and PWM are required to complete the regulator. Any voltage-mode PWM controller may be used, but the LT3525 is particularly well suited to high power, high efficiency applications such as the 10A circuit shown in Figure 13. In higher current regulators a small Schottky diode across the bottom MOSFET helps to reduce reverse-recovery switching losses. The LT1158 input pin can also be driven directly with a ramp or sawtooth. In this case, the DC level of the input waveform relative to the 1.4V threshold sets the LT1158 duty cycle. In the 5V to 3.3V converter circuit shown in Figure 11, an LT1431 controls the DC level of a triangle wave generated by a CMOS 555. The Figure 10 and 12 circuits use an RC network to ramp the LT1158 input back up to its 1.4V threshold following each switch cycle, setting a constant off time. Figure 4 shows the
U
W
U
U
efficiency vs. output current for the Figure 12 regulator with VIN = 12V. Current Limit in Switching Regulator Applications Current is sensed by the LT1158 by measuring the voltage across a current shunt (low valued resistor). Normally, this shunt is placed in the source lead of the top MOSFET (see Short-Circuit Protection in Bridge Applications). However, in step-down switching regulator applications, the remote current sensing capability of the LT1158 allows the actual inductor current to be sensed. This is done by placing the shunt in the output lead of the inductor as shown in Figure 3. Routing of the sense + and sense- PC traces is critical to prevent stray pickup. These traces must be routed together at minimum spacing and use a Kelvin connection at the shunt. When the voltage across RSENSE exceeds 110mV, the LT1158 fault pin begins to conduct. By feeding the fault signal back to a control input of the PWM, the LT1158 will assume control of the duty cycle forming a true current mode loop to limit the output current:
IOUT =
110mV in current limit RSENSE
In LT3525 based circuits, connecting the fault pin to the LT3525 soft-start pin accomplishes this function. In circuits where the LT1158 input is being driven with a ramp or sawtooth, the fault pin is used to pull down the DC level of the input. The constant off-time circuits shown in Figures 10 and 12 are unique in that they also use the current sense during normal operation. The LT1431 output reduces the normal LT1158 110mV fault conduction threshold such that the fault pin conducts at the required load current, thus discharging the input ramp capacitor. In current limit the LT1431 output turns off, allowing the fault conduction threshold to reach its normal value. The resistor RGS shown in Figure 3 is necessary to prevent output voltage overshoot due to charge coupled into the gate of the top MOSFET by a large start-up dv/dt on VIN. If DC operation of the top MOSFET is required, RGS must be 330k or greater to prevent loading the charge pump.
11
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. If zero standby current is required and the load returns to ground, then a switch can be inserted into the supply path of the LT1158 as shown in Figure 5. Resistor RGS ensures that the top MOSFET gate discharges, while the voltage across the bottom MOSFET goes to zero. The voltage drop across the P-channel supply switch must be less than 300mV, and RGS must be 330k or greater for DC operation. This technique is not recommended for applications which require the LT1158 VDS sensing function.
V+
100k VP0300 V+ 2N2222 100k CMOS ON/OFF TO OTHER CONTROL CIRCUITS V+ T SOURCE LT1158 T GATE DR T GATE FB RGS
+
GND
B GATE DR B GATE FB
1158 F05
Figure 5. Adding Zero Current Shutdown
Short-Circuit Protection in Bridge Applications The LT1158 protects the top power MOSFET from output shorts to ground, or in a full bridge application, shorts across the load. Both standard 3-lead MOSFETs and current-sensing 5-lead MOSFETs can be protected. The bottom MOSFET is not protected from shorts to supply. Current is sensed by measuring the voltage across a current shunt in the source lead of a standard 3-lead MOSFET (Figure 6). For the current-sensing MOSFET
T SOURCE 5V 10k FAULT SENSE - LT1158 SENSE +
12
U
W
U
U
shown in Figure 7, the sense resistor is inserted between the sense and Kelvin leads. The sense+ and sense- PC traces must be routed together at minimum spacing to prevent stray pickup, and a Kelvin connection must be used at the current shunt for the 3lead MOSFET. Using a twisted pair is the safest approach and is recommended for sense runs of several inches. When the voltage across RSENSE exceeds 110mV, the LT1158 fault pin begins to conduct, signaling a fault condition. The current in a short circuit ramps very rapidly, limited only by the series inductance and ultimately the MOSFET and shunt resistance. Due to the response time of the LT1158 current limit loop, an initial current spike of
V+
+
T GATE DR T GATE FB
+
5V 10k FAULT LT1158
T SOURCE SENSE + RSENSE SENSE -
1158 F06
LOAD
Figure 6. Short-Circuit Protection with Standard MOSFET
V+
+
T GATE DR T GATE FB SENSE KELVIN
RSENSE OUTPUT
1158 F07
Figure 7. Short-Circuit Protection with Current-Sensing MOSFET
LT1158
APPLICATIONS INFORMATION
from 2 to 5 times the final value will be present for a few s, 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 (0.5H) inductor in series with the output. value of RSENSE for the 5-lead MOSFET increases by the current sensing ratio (typically 1000 - 3000), thus eliminating the need for a low valued shunt. V is in the range of 1V to 3V in most applications. Assuming a dead short, the MOSFET dissipation will rise to VSUPPLY x ISC. For example, with a 24V supply and ISC = 10A, the dissipation would be 240W. To determine how long the MOSFET can remain at this dissipation level before it must be shut down, refer to the SOA curves given in the MOSFET data sheet. For example, an IRFZ34 would be safe if shut down within 10ms. A Tektronix A6303 current probe is highly recommended for viewing output fault currents. If Short-Circuit Protection is Not Required
LT1158 F08
5A/DIV
ISC
5s/DIV
Figure 8. Top MOSFET Short-Circuit Turn-On current
If neither the enable nor input pins are pulled low in response to the fault indication, the top MOSFET current will recover to a steady-state value ISC regulated by the LT1158 as shown in Figure 8: 150mV ISC = RSENSE 150mV RSENSE = ISC
Standard 3-Lead MOSFET
-2
r 150mV 150mV ISC = 1- V RSENSE
(
)
r 150mV 150mV RSENSE = 1- ISC V
(
)
-2
5-Lead MOSFET
r = current sense ratio, V = VGS = VGS - VT The time for the current to recover to ISC following the initial current spike is approximately QGS/0.5mA, where QGS is the MOSFET gate-to-source charge. ISC need not be set higher than the required start-up current for motors (see Starting High In-Rush Current Loads). Note that the
U
W
U
U
In applications which do not require the current sense capability of the LT1158, the sense pins 11 and 12 should both be connected to pin 13, and the fault pin 5 left open. The enable pin 4 may still be used to shut down the device. Note, however, that when unprotected the top MOSFET can be easily (and often dramatically) destroyed by even a momentary short. Self-Protection with Automatic Restart When using the current sense circuits of Figures 6 and 7, local shutdown can be achieved by connecting the fault pin through resistor RF to the enable pin as shown in Figure 9. An optional thermostat mounted to the load or MOSFET heatsink can also be used to pull enable low. An internal 25A current source normally keeps the enable capacitor CEN charged to the 7.5V clamp voltage (or to V +, for V+ < 7.5V). When a fault occurs, CEN is discharged to below the enable low threshold (1.15V typ.) which shuts down both MOSFETs. When the fault pin or thermostat releases, CEN recharges to the upper enable threshold where restart is attempted. In a sustained short circuit, fault will again pull low and the cycle will repeat until the short is removed. The time to shut down for a DC input or thermal fault is given by: tSHUTDOWN = (100 + 0.8RF) CEN DC input
13
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 ENABLE CEN 1F
25A
+
7.5V RF 1k FAULT LT1158
OPTIONAL THERMOSTAT CLOSE ON RISE AIRPAX #67FXXX
1158 F09
Figure 9. Self-Protection with Auto Restart
tSHUTDOWN becomes more difficult to analyze when the output is shorted with a PWM input. This is because the fault pin only conducts when fault currents are actually present in the MOSFET. Fault does not conduct while the input is low in Figures 6 and 7 or during the interval IDS = 0 in Figure 8. Thus tSHUTDOWN will safely increase when the duty cycle of the current in the top MOSFET is low, maintaining the average MOSFET current at a relatively constant level. The length of time following shutdown before restart is attempted is given by:
1.5V 4 t RESTART = CEN = 6 x 10 CEN 25A
In Figure 9, the top MOSFET would shut down after being in DC current limit for 0.9ms and try to restart at 60ms intervals, thus producing a duty cyle of 1.5% in short circuit. The resulting average top MOSFET dissipation during a short is easily measured by taking the product of the supply voltage and the average supply current. Starting High In-Rush Current Loads The LT1158 has a VDS sensing function which allows more than ISC to flow in the top MOSFET providing that the
14
U
W
U
U
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). Again adjusting RDS(ON) for temperature, the worst-case start currents are:
ISTART = ISTART =
( ) ()
1.2V
1.2V
1 + RDS ON + RSENSE
3-Lead MOSFET
(1+ )RDS(ON)
5-Lead MOSFET
Properly sizing the MOSFET for ISTART allows inductive loads with long time constants, such as motors with high mechanical inertia, to be started. Returning to the example used in Power MOSFET Selection, an IRFZ34 (RDS(ON) = 0.05 max.) was selected for operation at 5A. If the short-circuit current is also set at 5A, what start current can be supported? From the equation for RSENSE, a 0.03 shunt would be required, allowing the worst-case start current to be calculated:
ISTART =
(1.7)0.05 +0.03
1 .2V
= 10A
This calculation gives the minimum current which could be delivered with the IRFZ34 at TJ = 125C without activating the fault pin on the LT1158. If more start current is required, using an IRFZ44 (RDS(ON) = 0.028 max.) would increase ISTART to over 15A at TJ = 110C, even though the short-circuit current remains at 5A. In order for the VDS sensing function to work properly, the supply pins for the LT1158 must be connected at the drain of the top MOSFET, which must be properly decoupled (see Ugly Transient Issues). Driving Lamps Incandescent lamps represent a challenging load because they have much in common with a short circuit when cold. The top gate driver in the LT1158 can be configured to turn on large lamps while still protecting the power MOSFET
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. A good guideline is to choose RSENSE to set ISC at approximately twice the steady state "on" current of the lamp(s). tSHUTDOWN is then made long enough to guarantee that the lamp filaments heat and drop out of current limit before the enable capacitor discharges to the enable low threshold. For a short circuit, the enable capacitor will continue to discharge below the threshold, shutting down the top MOSFET. The LT1158 will then go into the automatic restart mode described in Self-Protection with Automatic Restart above. The time constant for an incandescent filament is tens of milliseconds, which means that tSHUTDOWN will have to be longer than in most other applications. This places increased SOA demands on the MOSFET during a short circuit, requiring that a larger than normal device be used. A protected high current lamp driver application is shown in Figure 18.
TYPICAL APPLICATIONS
5V TO 10V INPUT (USE LOGIC-LEVEL Q1, Q2) 1N4148 100k 8V TO 20V INPUT (USE STANDARD Q1, Q2 AND CONNECT BOOST DIODE TO PIN 1) 16 Q1 15 14 13 100 100 Q2 7 Q1, Q2: IRLZ44 (LOGIC-LEVEL) IRFZ44 (STANDARD) L1: HURRICANE LAB HL-KK122T/BB RS: VISHAY/DALE TYPE LVR-3 VISHAY/ULTRONIX RCS01, SM1 ISOTEK CORP. ISA-PLAN SMR CONSTANT OFF TIME CURRENT MODE CONTROL LOOP FREQUENCY = 1 tOFF 8 24k 510 1000pF 0.05F 1k 1N4148 1 2 3 4 LT1431 8 7 6 5
LT1158 F10
x
VP0300 INSERT FOR ZERO POWER SHUTDOWN
1 2 0.01F 3 4 10F 5 6
BOOST DR V
+
BIAS ENABLE LT1158 FAULT INPUT GND B GATE FB
100k 2N2222 CMOS ON/OFF
+
(1 - VV ) WHERE t
OUT IN
OFF 10s
Figure 10. High Efficiency 3.3V Step-Down Switching Regulator (Requires No Heatsinks)
U
W
U
U
U
BOOST T GATE DR T GATE FB T SOURCE SENSE
+
500F LOW ESR SHORT-CIRCUIT RS CURRENT = 8A 0.015 +3.3V/6A OUTPUT -
0.1F
680k
L1 22H
+
11
+ 12
+
1000F LOW ESR
SENSE - V
+ 10
B GATE DR
9 1.62k 1%
4.99k 1% 200pF
15
LT1158
TYPICAL APPLICATIONS
DRIVER SUPPLY 10V TO 15V (CAN BE POWERED FROM VIN WITH LOGIC-LEVEL Q1, Q2) 0.01F 1 2 3 3.3k 4 LT1431 16k 0.33F VIN 4.5V TO 6V
8 7 6 5 200pF 0.01F 4.99k 1% SHUTDOWN
1000pF 1 2 24k 3 4 CMOS 555
8 7 6 5 RX 1% 470pF
VOUT RX (1%)
2.90V 3.05V 806 1.10k
3.30V 1.62k
3.45V 3.60V 1.91k 2.21k
Figure 11. 5V to 3.XXV,15A Converter (Uses PC Board Area for Heatsink)
8V TO 20V INPUT 1N4148 100k
x
VP0300
INSERT FOR ZERO POWER SHUTDOWN 100k 2N2222 CMOS ON/OFF
+
10F
24k 510 L1: COILTRONICS CTX50-5-52 RS: VISHAY/DALE TYPE LVR-3 VISHAY/ULTRONIX RCS01, SM1 ISOTEK CORP. ISA-PLAN SMR CONSTANT OFF TIME CURRENT MODE CONTROL LOOP V FREQUENCY = 1 - OUT VIN tOFF 1 SEE FIGURE 4 FOR EFFICIENCY CURVE 1000pF 0.05F 1k 1N4148 1 2 3 4 LT1431 8 7 6 5
LT1158 F12
(
) WHERE t
OFF 10s
Figure 12. High Efficiency 5V Step-Down Switching Regulator (Requires No Heatsinks)
16
U
+
10F 1 2 3 4 5 6 7 8 BOOST DR V+ BIAS ENABLE LT1158 FAULT INPUT GND B GATE FB BOOST T GATE DR T GATE FB T SOURCE SENSE+ SENSE - V+ B GATE DR 16 15 14 13 12 11 10 9
BAS16
+
Q1
220F 10V OS-CON x 4 SHORT-CIRCUIT CURRENT = 22A RS
0.22F 500k L1 8H
+
-
0.01 EA
+
VOUT 15A 330F 6.3V AVX x 4
Q2
LT1158 F11
Q1, Q2: MTB75N05HD (USE WITH 10V TO 15V DRIVER SUPPLY) MTB75N03HDL (USE WITH VIN DRIVER SUPLY) CMOS 555: LMC555 OR TLC555
L1: COILTRONICS CTX02-12171-1 RS: KRL/BANTRY SL-1R010J x 2
1 2 0.01F 3 4 5 6 7 8
BOOST DR V+ BIAS ENABLE LT1158 FAULT INPUT GND B GATE FB
BOOST T GATE DR T GATE FB T SOURCE SENSE+ SENSE - V+ B GATE DR
16 IRFZ34 15 14 13 12 11 10 9 100 100 IRFZ44
+
500F LOW ESR SHORT-CIRCUIT CURRENT = 6A
0.1F
510k
L1 50H
RS 20m
+
-
+
+5V/4A OUTPUT 1000F LOW ESR
LT1158
TYPICAL APPLICATIONS
SHUTDOWN 0.01F 4.7k 1 16 15 0.1F 2 EXT SYNC 2.2nF 5 0.01F 6 27k 7 1F 510 8 9 10 7 GND B GATE FB V+ B GATE DR 10 9 (2) IRFZ44 11 3 4 f = 25kHz LT3525 12 1N4148 5 6 FAULT INPUT 2 4.7k 1N4148 1F 1 BOOST DR V+ BIAS ENABLE LT1158 BOOST T GATE DR T GATE FB T SOURCE SENSE+ SENSE 16 IRFZ44 15 14 13 12 0.1F 330k SHORT-CIRCUIT CURRENT = 15A L1 70H RS 0.007 INPUT 30V MAX
* 3.4k
+
14 10F 13 1N4148
30k
* ADD THESE COMPONENTS TO IMPLEMENT
LOW-DROPOUT 12V REGULATOR
Figure 13. 90% Efficiency 24V to 5V 10A Switching Regulator 95% Efficiency 24V to 12V 10A Low Dropout Switching Regulator
MOTOR SPEED 0 TO 100% 10k
+
1F 7.5k
1N5231A
1 2 13k 3 4 CMOS 555
8 7 6 5 2.2nF
THE CMOS 555 IS USED AS A 25kHz TRIANGLE-WAVE OSCILLATOR DRIVING THE LT1158 INPUT PIN. THE D.C. LEVEL OF THE TRIANGLE WAVE IS SET BY THE POTENTIOMETER ON THE CMOS 555 SUPPLY PIN, AND ALLOW ADJUSTMENT OF THE LT1158 DUTY CYCLE FROM 0 TO 100%.
Figure 14. Potentiometer-Adjusted Open Loop Motor Speed Control with Short-Circuit Protection
U
+
+
500F EA LOW ESR
+
0.01F 3 4
+
- +
5V OR 12V* 1000F LOW ESR
- 11
*
330pF
10k
8
+
MBR340
LT1158 F13
L1: MAGNETICS CORE #55585-A2 30 TURNS 14GA MAGNET WIRE
RS: DALE TYPE LVR-3 ULTRONIX RCS01
5.1k 1N4148 1 2 10F 16 15 14 13 24 0.1F
10V TO 30V
BOOST DR V
+
BOOST T GATE DR T GATE FB T SOURCE LT1158 SENSE
+
1000F LOW ESR
+
0.33F
0.01F 3 4 1k 5 6 510 7 8
BIAS ENABLE FAULT INPUT GND B GATE FB
Q1
+ 12
+
START CURRENT = 15A MINIMUM 0.02
SENSE - V+ B GATE DR
11
-
10 9 24 Q2
CMOS 555: LMC555 OR TLC555 Q1, Q2: MTP35N06E
LT1158 F14
17
LT1158
TYPICAL APPLICATIONS
7.2V NOMINAL BAT85 1 2 BOOST DR V+ BIAS ENABLE LT1158 FAULT INPUT GND B GATE FB BOOST T GATE DR T GATE FB T SOURCE SENSE SENSE 16 15 14 13 15 0.1F
+
10F STOP (FREE RUN) 1N4148
+
1F
PWM
Figure 15. High Efficiency 6-Cell NiCd Protected Motor Drive
LT1158 ENABLE FAULT 5V INPUT A
SHUTDOWN COMMUTATING LOGIC PWM CONTROLS LT1158 INPUTS POSITION FEEDBACK CONTROLS LT1158 ENABLE INPUTS
1158 F16
18
U
+
100F
0.01F 3 4 1k 5 6 7 8
Q1 START CURRENT = 25A MINIMUM RS 0.015
+ 12 - 11
+
V+ B GATE DR
10 9 15
-
Q2
Q1, Q2: IRLZ44 (LOGIC-LEVEL) RS: DALE TYPE LVR-3 ULTRONIX RCS01
LT1158 F15
V+ LT1158 ENABLE FAULT INPUT
V+ LT1158 ENABLE B FAULT INPUT
V+
C
Figure 16. 3-Phase Brushless DC Motor Control
LT1158
TYPICAL APPLICATIONS
1N4148 1 2 0.01F 3 ENABLE A FAULT A INPUT A 4 10F 5 6 7 8 16 0.1F 15 14 13 12 15 D1 Q1 10V TO 30V BOOST DR V
+
BIAS ENABLE LT1158 FAULT INPUT GND B GATE FB
+
1 2 0.01F 3 4
BOOST DR V
+
BIAS ENABLE LT1158 FAULT INPUT GND B GATE FB
ENABLE B FAULT B INPUT B
+
10F 5 6 7 8
Control Logic for Sign/Magnitude Drive
ENABLE A 74HC02 FAULT A INPUT A PWM PWM DIRECTION 1N4148 STOP (FREE RUN) ENABLE B
+
1F
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
BOOST T GATE DR T GATE FB T SOURCE SENSE+ SENSE V
+
470F LOW ESR
SIDE A: SHOWS STANDARD MOSFET CONNECTION
+
RS 0.015 Q2 15
- 11
-
2.4k
+ 10
B GATE DR
9
1N4148 16 15 14 13 12 11 10 9 15 47 Q4 Q1, Q3: IRF540 (STANDARD) IRC540 (SENSE FET) Q2, Q4: IRFZ44 D1, D2: BAT83 RS: DALE TYPE LVR-3 ULTRONIX RCS01
LT1158 F17a
+
15 D2 0.1F Q3 470F LOW ESR
SIDE B: SHOWS CURRENT-SENSING MOSFET CONNECTION
BOOST T GATE DR T GATE FB T SOURCE SENSE+ SENSE - V+ B GATE DR
+
-
2.4k
Control Logic for Locked Anti-Phase Drive Motor stops if either side is shorted to ground
5V 74HC132 5.1k 0.01F FAULT A INPUT A ENABLE A
150k 0.1F
ENABLE B 1N4148 FAULT B INPUT B
1158F17c
FAULT B INPUT B
1158F17b
Figure 17. 10A Full Bridge Motor Control
19
LT1158
TYPICAL APPLICATIONS
12V 1N4148 1 2 16 IRCZ44 15 14 13 12 11 10 9 ISC: 10A t SHUTDOWN = 50ms tRESTART = 600ms 51 MBR330 12V 55W 0.1F
+
10F
+
10F 6.2k 5 6 7 8
ON/OFF
Figure 18. High Current Lamp Driver with Short-Circuit Protection
PACKAGE DESCRIPTION
0.300 - 0.325 (7.620 - 8.255)
0.130 0.005 (3.302 0.127)
0.009 - 0.015 (0.229 - 0.381)
0.015 (0.381) MIN
(
+0.025 0.325 -0.015 8.255 +0.635 -0.381
)
0.125 (3.175) MIN
0.005 (0.127) RAD MIN
0.291 - 0.299 (7.391 - 7.595) (NOTE 2) 0.010 - 0.029 x 45 (0.254 - 0.737)
0 - 8 TYP 0.050 (1.270) TYP 0.394 - 0.419 (10.007 - 10.643)
0.009 - 0.013 (0.229 - 0.330)
NOTE 1 0.016 - 0.050 (0.406 - 1.270)
NOTE: 1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS. THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS. 2. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm).
20
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977
U
U
+
1000F
BOOST DR V+ BIAS ENABLE LT1158 FAULT INPUT GND B GATE FB
BOOST T GATE DR T GATE FB T SOURCE SENSE+ SENSE - V+ B GATE DR
0.01F 3 4
+
-
LT1158 F18
Dimensions in inches (millimeters) unless otherwise noted. N Package 16-Lead Plastic DIP
0.045 - 0.065 (1.143 - 1.651) 0.770 (19.558) MAX 16 15 14 13 12 11 10 9
0.065 (1.651) TYP
0.260 0.010 (6.604 0.254)
1 0.045 0.015 (1.143 0.381) 0.100 0.010 (2.540 0.254) 0.018 0.003 (0.457 0.076)
2
3
4
5
6
7
8
S Package 16-Lead Plastic SOL
0.093 - 0.104 (2.362 - 2.642) 0.037 - 0.045 (0.940 - 1.143) 16 15
0.398 - 0.413 (10.109 - 10.490) (NOTE 2) 14 13 12 11 10 9
0.004 - 0.012 (0.102 - 0.305)
NOTE 1
0.014 - 0.019 (0.356 - 0.482) TYP
1
2
3
4
5
6
7
8
LT/GP 0394 5K REV A * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1994

▲Up To Search▲

Price & Availability of LT1158

	To Download LT1158 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .