View LT1640L1_4299340.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

LT1640L/LT1640H Negative Voltage Hot Swap Controller
FEATURES
s s s s s s s
DESCRIPTIO
Allows Safe Board Insertion and Removal from a Live - 48V Backplane Operates from -10V to - 80V Programmable Inrush Current Programmable Electronic Circuit Breaker Programmable Overvoltage Protection Programmable Undervoltage Lockout Power Good Control Output
APPLICATIO S
s s s
Central Office Switching - 48V Distributed Power Systems Negative Power Supply Control
The LT(R)1640L/LT1640H is an 8-pin, negative voltage Hot SwapTM controller that allows a board to be safely inserted and removed from a live backplane. Inrush current is limited to a programmable value by controlling the gate voltage of an external N-channel pass transistor. The pass transistor is turned off if the input voltage is less than the programmable undervoltage threshold or greater than the overvoltage threshold. A programmable electronic circuit breaker protects the system against shorts. The PWRGD (LT1640L) or PWRGD (LT1640H) signal can be used to directly enable a power module. The LT1640L is designed for modules with a low enable input and the LT1640H for modules with a high enable input. The LT1640L/LT1640H is available in 8-pin PDIP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation. Hot Swap is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
GND GND R4 562k 1% R5 9.09k 1% UV = 37V R6 10k 1% 8 VDD 3 UV LT1640L 2 OV VEE 4 SENSE 5 GATE 6 (SHORT PIN)
PWRGD
1
INRUSH CURRENT 1A/DIV
DRAIN 7 1N4148
OV = 71V *
GATE - VEE 10V/DIV
3 - 48V 1
R1 0.02 5% 2
C1 150nF 25V 4
R2 10 5%
R3 18k C2 5% 3.3nF 100V 2 ON/OFF 1 9 VOUT+ VIN+ 8 SENSE + 7 TRIM 6 SENSE - 4 5 VOUT- VIN- LUCENT JW050A1-E 5V
DRAIN 50V/DIV VEE 50V/DIV
Q1 IRF530
* DIODES INC. SMAT70A THESE COMPONENTS ARE APPLICATION SPECIFIC AND MUST BE SELECTED BASED UPON OPERATING CONDITIONS AND DESIRED PERFORMANCE. SEE APPLICATIONS INFORMATION.
C3 0.1F 100V
+
C4 100F 100V
+
C5 100F 16V
CONTACT BOUNCE 5ms/DIV
1640 F06b
1640 TA01
U
Input Inrush Current
1640lhfb
U
U
1
LT1640L/LT1640H ABSOLUTE MAXIMUM RATINGS U WW U W
(Note 1), All Voltages Referred to VEE
Supply Voltage (VDD - VEE) .................... - 0.3V to 100V DRAIN, PWRGD, PWRGD Pins ............... - 0.3V to 100V SENSE, GATE Pins .................................... - 0.3V to 20V UV, OV Pins .............................................. - 0.3V to 60V Maximum Junction Temperature ......................... 125C
Operating Temperature Range LT1640LC/LT1640HC ............................. 0C to 70C LT1640LI/LT1640HI .......................... - 40C to 85C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C
PACKAGE/ORDER I FOR ATIO
TOP VIEW PWRGD 1 OV 2 UV 3 VEE 4 N8 PACKAGE 8-LEAD PDIP 8 7 6 5 VDD DRAIN GATE SENSE
ORDER PART NUMBER LT1640LCN8 LT1640LCS8 LT1640LIN8 LT1640LIS8 S8 PART MARKING 1640L 1640LI
PWRGD 1 OV 2 UV 3 VEE 4 N8 PACKAGE 8-LEAD PDIP
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 125C, JA = 120C/W (N8) TJMAX = 125C, JA = 150C/W (S8)
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 2), VDD = 48V, VEE = 0V unless otherwise noted.
SYMBOL DC VDD IDD VCB IPU IPD ISENSE VGATE VUVH VUVL VUVHY IINUV VOVH VOVL VOVHY IINOV Supply Operating Range Supply Current Circuit Breaker Trip Voltage GATE Pin Pull-Up Current GATE Pin Pull-Down Current SENSE Pin Current External Gate Drive UV Pin High Threshold Voltage UV Pin Low Threshold Voltage UV Pin Hysteresis UV Pin Input Current OV Pin High Threshold Voltage OV Pin Low Threshold Voltage OV Pin Hysteresis OV Pin Input Current VOV = VEE
q q
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
UV = 3V, OV = VEE, SENSE = VEE VCB = (VSENSE - VEE) Gate Drive On, VGATE = VEE Any Fault Condition VSENSE = 50mV (VGATE - VEE), 15V VDD 80V (VGATE - VEE), 10V VDD < 15V UV Low to High Transition UV High to Low Transition VUV = VEE OV Low to High Transition OV High to Low Transition
2
U
TOP VIEW 8 7 6 5 VDD DRAIN GATE SENSE
W
ORDER PART NUMBER LT1640HCN8 LT1640HCS8 LT1640HIN8 LT1640HIS8 S8 PART MARKING 1640H 1640HI
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 125C, JA = 120C/W (N8) TJMAX = 125C, JA = 150C/W (S8)
MIN 10
TYP
MAX 80
UNITS V mA mV A mA A V V V V mV A V V mV A
1640lhfb
q q q
1.3 40 - 30 24 50 - 45 50 - 20 13.5 8 1.243 1.223 20 - 0.02 1.198 1.165 1.223 1.203 20 - 0 .03
5 60 - 60 70 18 15 1.272 1.247 - 0.5 1.247 1.232 - 0.5
q q q q
10 6 1.213 1.198
q q q
LT1640L/LT1640H
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 2), VDD = 48V, VEE = 0V unless otherwise noted.
SYMBOL VPG VPGHY IDRAIN VOL PARAMETER Power Good Threshold Power Good Threshold Hysteresis Drain Input Bias Current PWRGD Output Low Voltage VDRAIN = 48V PWRGD (LT1640L), (VDRAIN - VEE) < VPG IOUT = 1mA IOUT = 5mA PWRGD (LT1640H), VDRAIN = 5V IOUT = 1mA PWRGD (LT1640L), VDRAIN =48V, VPWRGD = 80V PWRGD (LT1640H), (VDRAIN - VEE) < VPG
q q
ELECTRICAL CHARACTERISTICS
CONDITIONS VDRAIN - VEE, High to Low Transition
MIN 1.1 10
TYP 1.4 0.4 50 0.48 1.50 0.75 0.05
MAX 2.0 500 0.8 3.0 1.0 10
UNITS V V A V V V A k
PWRGD Output Low Voltage (PWRGD - DRAIN) IOH ROUT AC tPHLOV tPHLUV tPLHOV tPLHUV tPHLSENSE tPHLPG tPLHPG OV High to GATE Low UV Low to GATE Low OV Low to GATE High UV High to GATE High SENSE High to Gate Low DRAIN Low to PWRGD Low DRAIN Low to (PWRGD - DRAIN) High DRAIN High to PWRGD High DRAIN High to (PWRGD - DRAIN) Low Output Leakage Power Good Output Impedance (PWRGD to DRAIN)
q q q
2
6.5
Figures 1, 2 Figures 1, 3 Figures 1, 2 Figures 1, 3 Figures 1, 4 (LT1640L) Figures 1, 5 (LT1640H) Figures 1, 5 (LT1640L) Figures 1, 5 (LT1640H) Figures 1, 5 2
1.7 1.5 5.5 6.5 3 0.5 0.5 0.5 0.5 4
s s s s s s s s s
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
Note 2: All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to VEE unless otherwise specified.
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
1.8 1.7
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
1.6 1.5 1.4 1.3 1.2 1.1 0 0 20 80 60 SUPPLY VOLTAGE (V) 40 100
1640 G01
GATE VOLTAGE (V)
UW
Supply Current vs Temperature
1.6 1.5 1.4 1.3 1.2 1.1
Gate Voltage vs Supply Voltage
15 14 13 12 11 10 9 8 7
1.0 - 50
- 25
0 25 50 TEMPERATURE (C)
75
100
1640 G02
6 0 20 80 60 40 SUPPLY VOLTAGE (V) 100
1640 G03
1640lhfb
3
LT1640L/LT1640H TYPICAL PERFOR A CE CHARACTERISTICS
Gate Voltage vs Temperature
15.0 14.5 14.0 13.5 13.0 12.5 12.0 - 50 TRIP VOLTAGE (mV)
GATE PULL-UP CURRENT (A)
GATE VOLTAGE (V)
- 25
25 50 0 TEMPERATURE (C)
Gate Pull-Down Current vs Temperature
55 0.5
PWRGD OUTPUT LOW VOLTAGE (V)
VGATE = 2V
GATE PULL-DOWN CURRENT (mA)
OUTPUT IMPEDANCE (k)
52
49
46
43
40 - 50
- 25
0 50 25 TEMPERATURE (C)
PIN FUNCTIONS
PWRGD/PWRGD (Pin 1): Power Good Output Pin. This pin will toggle when VDRAIN is within VPG of VEE. This pin can be connected directly to the enable pin of a power module. When the DRAIN pin of the LT1640L is above VEE by more than VPG, the PWRGD pin will be high impedance, allowing the pull-up current of the module's enable pin to pull the pin high and turn the module off. When VDRAIN drops below VPG, the PWRGD pin sinks current to VEE, pulling the enable pin low and turning on the module. When the DRAIN pin of the LT1640H is above VEE by more than VPG, the PWRGD pin will sink current to the DRAIN pin which pulls the module's enable pin low, forcing it off. When VDRAIN drops below VPG, the PWRGD sink current is turned off and a 6.5k resistor is connected between PWRGD and DRAIN, allowing the module's pull-up current to pull the enable pin high and turn on the module. OV (Pin 2): Analog Overvoltage Input. When OV is pulled above the 1.223V low to high threshold, an overvoltage condition is detected and the GATE pin will be immediately pulled low. The GATE pin will remain low until OV drops below the 1.203V high to low threshold.
1640lhfb
4
UW
75
1640 G04
Circuit Breaker Trip Voltage vs Temperature
55 54 53 52 51 50 49 48 - 50
48 47 46 45 44 43 42 41
Gate Pull-Up Current vs Temperature
VGATE = 0V
100
- 25
50 0 25 TEMPERATURE (C)
75
100
1640 G05
40 - 50
- 25
0 25 50 TEMPERATURE (C)
75
100
1640 G06
PWRGD Output Low Voltage vs Temperature (LT1640L)
8
IOUT = 1mA 0.4
PWRGD Output Impedance vs Temperature (LT1640H)
VDRAIN - VEE > 2.4V 7 6 5 4 3 2 - 50
0.3
0.2
0.1
75
100
1640 G07
0 - 50
- 25
25 50 0 TEMPERATURE (C)
75
100
1640 G08
- 25
0 25 50 TEMPERATURE (C)
75
100
1640 G09
U
U
U
LT1640L/LT1640H
PIN FUNCTIONS
UV (Pin 3): Analog Undervoltage Input. When UV is pulled below the 1.223V high to low threshold, an undervoltage condition is detected and the GATE pin will be immediately pulled low. The GATE pin will remain low until UV rises above the 1.243 low to high threshold. The UV pin is also used to reset the electronic circuit breaker. If the UV pin is cycled low and high following the trip of the circuit breaker, the circuit breaker is reset and a normal power-up sequence will occur. VEE (Pin 4): Negative Supply Voltage Input. Connect to the lower potential of the power supply. SENSE (Pin 5): Circuit Breaker Sense Pin. With a sense resistor placed in the supply path between VEE and SENSE, the circuit breaker will trip when the voltage across the resistor exceeds 50mV. Noise spikes of less than 2s are filtered out and will not trip the circuit breaker. If the circuit breaker trip current is set to twice the normal operating current, only 25mV is dropped across the sense resistor during normal operation. To disable the circuit breaker, VEE and SENSE can be shorted together. GATE (Pin 6): Gate Drive Output for the External N-Channel. The GATE pin will go high when the following start-up conditions are met: the UV pin is high, the OV pin is low and (VSENSE - VEE) < 50mV. The GATE pin is pulled high by a 45A current source and pulled low with a 50mA current source. DRAIN (Pin 7): Analog Drain Sense Input. Connect this pin to the drain of the external N-channel and the V - pin of the power module. When the DRAIN pin is below VPG, the PWRGD or PWRGD pin will toggle. VDD (Pin 8): Positive Supply Voltage Input. Connect this pin to the higher potential of the power supply inputs and the V + pin of the power module. The input supply voltage ranges from 10V to 80V.
BLOCK DIAGRA
UV
REF
OV
-+
VEE SENSE
+
-
W
+
+
-
-
U
U
U
VDD
VCC AND REFERENCE GENERATOR
VCC REF OUTPUT DRIVE PWRGD/PWRGD
50mV
LOGIC AND GATE DRIVE
+ + -
VEE VPG
-
1640 BD
GATE
DRAIN
1640lhfb
5
LT1640L/LT1640H
TEST CIRCUIT
V+ 5V
R 5k PWRGD/PWRGD VDD OV DRAIN
+ -
VDRAIN
48V
VOV
LT1640L/LT1640H UV GATE SENSE
VUV VEE VSENSE
1640 F01
Figure 1. Test Circuit
TIMING DIAGRAMS
2V OV 0V tPHLOV GATE tPLHOV GATE
1640 F02
1.223V
1V
Figure 2. OV to GATE Timing
SENSE
50mV
tPHLSENSE GATE
1V
1640 F04
Figure 4. SENSE to GATE Timing
6
W
UW
1.203V
2V UV 0V
1.223V
1.243V
tPHLUV
tPLHUV
1V
1V
1V
1640 F03
Figure 3. UV to GATE Timing
1.8V DRAIN VEE tPLHPG PWRGD VEE
1.8V
1.4V
tPHLPG
1V
1V
DRAIN 0V tPLHPG PWRGD VPWRGD - VDRAIN = 0V
1.4V
tPHLPG
1V
1V
1640 F05
Figure 5. DRAIN to PWRGD/PWRGD Timing
1640lhfb
LT1640L/LT1640H
APPLICATIONS INFORMATION
Hot Circuit Insertion When circuit boards are inserted into a live - 48V backplane, the bypass capacitors at the input of the board's power module or switching power supply can draw huge transient currents as they charge up. The transient currents can cause permanent damage to the board's components and cause glitches on the system power supply. The LT1640 is designed to turn on a board's supply voltage in a controlled manner, allowing the board to be safely inserted or removed from a live backplane. The chip also provides undervoltage, overvoltage and overcurrent protection while keeping the power module off until its input voltage is stable and within tolerance. Power Supply Ramping The input to the power module on a board is controlled by placing an external N-channel pass transistor (Q1) in the power path (Figure 6a, all waveforms are with respect to the VEE pin of the LT1640). R1 provides current fault detection and R2 prevents high frequency oscillations. Resistors R4, R5 and R6 provide undervoltage and overvoltage sensing. By ramping the gate of Q1 up at a slow rate, the surge current charging load capacitors C3 and C4 can be limited to a safe value when the board makes connection. Resistor R3 and capacitor C2 act as a feedback network to accurately control the inrush current. The inrush current can be calculated with the following equation: IINRUSH = (45A * CL)/C2 where CL is the total load capacitance, C3 + C4 + module input capacitance.
GND GND
(SHORT PIN)
R4 562k 1% UV = 37V R5 9.09k 1% R6 10k 1%
8 VDD 3 UV LT1640H 2 OV VEE 4 SENSE 5 GATE 6 2x 1N4148 DRAIN 7 PWRGD 1 C3 0.1F 100V
OV = 71V
* R1 0.02 5% 1 2 C1 150nF 25V 4 R2 R3 10 18k C2 5% 5% 3.3nF 100V
1640 F06a
3 - 48V * DIODES INC. SMAT70A
Figure 6a. Inrush Control Circuitry
U
W
U
U
+
VICOR VI-J3D-CY C4 100F 100V VIN+ GATE IN VIN- VOUT- VOUT+ 5V
+
C5 100F 16V
Q1 IRF530
1640lhfb
7
LT1640L/LT1640H
APPLICATIONS INFORMATION
Capacitor C1 and resistor R3 prevent Q1 from momentarily turning on when the power pins first make contact. Without C1 and R3, capacitor C2 would pull the gate of Q1 up to a voltage roughly equal to VEE * C2/CGS(Q1) before the LT1640 could power up and actively pull the gate low. By placing capacitor C1 in parallel with the gate capacitance of Q1 and isolating them from C2 using resistor R3 the problem is solved. The value of C1 should be:
VINMAX - VTH * (C 2 + C GD ) VTH
where VTH is the MOSFET's minimum gate threshold and VINMAX is the maximum operating input voltage.
INRUSH CURRENT 1A/DIV
GATE - VEE 10V/DIV
DRAIN 50V/DIV VEE 50V/DIV CONTACT BOUNCE 5ms/DIV
1640 F06b
Figure 6b. Inrush Control Waveforms
8
U
W
U
U
R3's value is not critical and is given by (VINMAX + VGATE)/ 5mA. The waveforms are shown in Figure 6b. When the power pins make contact, they bounce several times. While the contacts are bouncing, the LT1640 senses an undervoltage condition and the GATE is immediately pulled low when the power pins are disconnected. Once the power pins stop bouncing, the GATE pin starts to ramp up. When Q1 turns on, the GATE voltage is held constant by the feedback network of R3 and C2. When the DRAIN voltage has finished ramping, the GATE pin then ramps to its final value.
1640lhfb
LT1640L/LT1640H
APPLICATIONS INFORMATION
Electronic Circuit Breaker The LT1640 features an electronic circuit breaker function that protects against short circuits or excessive supply currents. By placing a sense resistor between the VEE and SENSE pin, the circuit breaker will be tripped whenever the voltage across the sense resistor is greater than 50mV for more than 3s as shown in Figure 7. Note that the circuit breaker threshold should be set sufficiently high to account for the sum of the load current and the inrush current. If the load current can be controlled by the PWRGD/PWRGD pin (as in Figure 6a), the threshold can be set lower, since it will never need to accommodate inrush current and load current simultaneously. When the circuit breaker trips, the GATE pin is immediately pulled to VEE and the external N-channel turns off. The GATE pin will remain low until the circuit breaker is reset by pulling UV low, then high or cycling power to the part. If more than 3s deglitching time is needed to reject current noise, an external resistor and capacitor can be added to the sense circuit as shown in Figure 8. R7 and C3 act as a lowpass filter that will slow down the SENSE pin voltage from rising too fast. Since the SENSE pin will source current, typically 20A, there will be a voltage drop on R7. This voltage will be counted into the circuit breaker trip voltage just as the voltage across the sense resistor. A small resistor is recommended for R7. A 100 for R7 will cause a 2mV error. The following equation can be used to estimate the delay time at the SENSE pin:
V( t) - V( tO ) t = -R * C * In 1 - Vi - V( tO )
INRUSH CURRENT 2A/DIV
GATE - VEE 4V/DIV
VEE 50V/DIV
3 - 48V
4ms/DIV
Figure 7. Start-Up Into a Short Circuit
U
W
U
U
Where V(t) is the circuit breaker trip voltage, typically 50mV. V(tO) is the voltage drop across the sense resistor before the short or over current condition occurs. Vi is the voltage across the sense resistor when the short current or over current is applied on it. Example: A system has a 1A current load and a 0.02 sense resistor is used. An extended delay circuit needs to be designed for a 50s delay time after the load jumps to 5A. In this case: V(t) = 50mV V(tO) = 20mV Vi = 5A * 0.02 = 100mV If R7 = 100, then C3 = 1F.
GND GND
(SHORT PIN)
8 R4 562k 1% UV = 37V R5 9.09k 1% R6 10k 1% VDD 3 UV LT1640L 2 OV VEE 4 C3 1N4148 * R1 0.02 5% 1 2 R7 C1 150nF 25V 4 R2 R3 10 18k C2 5% 5% 3.3nF 100V Q1 IRF530
1640 F08
PWRGD
1
OV = 71V
+
SENSE 5 GATE 6 DRAIN 7
CL 100F 100V
1640 F07
* DIODES INC. SMAT70A
Figure 8. Extending the Short-Circuit Protection Delay
1640lhfb
9
LT1640L/LT1640H
APPLICATIONS INFORMATION
Under some conditions, a short circuit at the output can cause the input supply to dip below the UV threshold, resetting the circuit breaker immediately. The LT1640 then cycles on and off repeatedly until the short is removed. This can be minimized by adding a deglitching delay to the UV pin with a capacitor from UV to VEE. This capacitor forms an RC time constant with the resistors at UV, allowing the input supply to recover before the UV pin resets the circuit breaker. A circuit that automatically resets the circuit breaker after a current fault is shown in Figure 9.
(SHORT PIN) GND GND R7 1M 5% C4 1F 100V R9 10k 1% 3 * Q3 ZVN3310 D1 1N4148 - 48V * DIODES INC. SMAT70A R8 510k 5% R1 0.02 5% 1 2 C1 150nF 25V 4 R5 19.1k 1% R6 562k 1% R4 562k 1% 8 VDD 3 UV LT1640L 2 OV VEE 4 SENSE 5 GATE 6 1N4148 R2 R3 10 18k C2 5% 5% 3.3nF 100V Q1 IRF530
1640 F09a
2
Q2 2N2222
NODE 2 50V/DIV
GATE 2V/DIV
Figure 9. Automatic Restart After Current Fault
1640lhfb
10
U
W
U
U
Transistors Q2 and Q3 along with R7, R8, C4 and D1 form a programmable one-shot circuit. Before a short occurs, the GATE pin is pulled high and Q3 is turned on, pulling node 2 to VEE. Resistor R8 turns off Q2. When a short occurs, the GATE pin is pulled low and Q3 turns off. Node 2 starts to charge C4 and Q2 turns on, pulling the UV pin low and resetting the circuit breaker. As soon as C4 is fully charged, R8 turns off Q2, UV goes high and the GATE starts to ramp up. Q3 turns back on and quickly pulls node 2 back to VEE. Diode D1 clamps node 3 one diode drop below VEE. The duty cycle is set to 10% to prevent Q1 from overheating.
PWRGD
1
+
DRAIN 7
C3 100F 100V
3
1s/DIV
1640 F09b
LT1640L/LT1640H
APPLICATIONS INFORMATION
Undervoltage and Overvoltage Detection The UV (Pin 3) and OV (Pin 2) pins can be used to detect undervoltage and overvoltage conditions at the power supply input. The UV and OV pins are internally connected to analog comparators with 20mV of hysteresis. When the UV pin falls below its threshold or the OV pin rises above its threshold, the GATE pin is immediately pulled low. The GATE pin will be held low until UV is high and OV is low. The undervoltage and overvoltage trip voltages can be programmed using a three resistor divider as shown in Figure 10a. With R4 = 562k, R5 = 9.09k and R6 = 10K, the undervoltage threshold is set to 37V and the overvoltage threshold is set to 71V. The resistor divider will also gain up the 20mV hysteresis at the UV pin and OV pin to 0.6V and 1.2V at the input respectively. More hysteresis can be added to the UV threshold by connecting resistor R3 between the UV pin and the GATE pin as shown in Figure 10b.
VUV = 1.223
R4 + R5+ R6 VOV = 1.223 R6
( (
R4 + R5+ R6 R5 + R6
Figure 10a. Undervoltage and Overvoltage Sensing
GND GND R4 506k 1% UV UV OV = 37.6V = 43V = 71V R5 8.87k 1%
R2 16.9k 1%
* 3 - 48V * DIODES INC. SMAT70A 1
Figure 10b. Programmable Hysteresis for Undervoltage Detection
1640lhfb
U
W
U
U
GND GND
(SHORT PIN)
8
) )
R4 3 R5 2 R6 OV UV
VDD LT1640L LT1640H VEE 4
- 48V
1640 F10a
(SHORT PIN)
8 VDD 2 R1 562k 1% R3 1.62M 1% OV LT1640L /LT1640H 3 UV VEE 4 SENSE 5 C1 150nF 25V 4 2 Q1 1640 F10b IRF530 GATE 6 R6 10 5%
R1 0.02 5%
11
LT1640L/LT1640H
APPLICATIONS INFORMATION
The new threshold voltage when the input moves from low to high is:
R2 * R3 + R1 * R3 + R1 * R2 VUV,LH = VUVH R2 * R3 R4 + R5 VOV = VOVH R5
where VUVH is typically 1.243V. The new threshold voltage when the input moves from high to low is:
R2 * R3 + R1 * R3 + R1 * R2 R1 VUV,HL = VUVL - VGATE * R2 * R3 R3
where VUVL is typically 1.223V. The new hysteresis value will be:
R2 * R3 + R1 * R3 + R1 * R2 R1 VHYS = VUVHY + VGATE * R2 * R3 R3
With R1 = 562k, R2 = 16.9k and R3 = 1.62M, VGATE = 13.5V and VUVHY = 20mV, the undervoltage threshold will be 43V (from low to high) and 37.6V (from high to low). The hysteresis is 5.4V. A separate resistor divider should be used to set the overvoltage threshold given by:
GND GND
(SHORT PIN)
R4 3 R5 2 R6
LT1640H UV
+ -
OV
VPG
VEE 4 *
SENSE 5 C1
3 - 48V * DIODES INC. SMAT70A 1
R1 2
Figure 11. Active High Enable Module
1640lhfb
12
U
+ -
W
U
U
With R4 = 506k, R5 = 8.87k and VOVH = 1.223V, the overvoltage threshold will be 71V. PWRGD/PWRGD Output The PWRGD/PWRGD output can be used to directly enable a power module when the input voltage to the module is within tolerance. The LT1640L has a PWRGD output for modules with an active low enable input, and the LT1640H has a PWRGD output for modules with an active high enable input. When the DRAIN voltage of the LT1640H is high with respect to VEE (Figure 11), the internal transistor Q3 is turned off and R7 and Q2 clamp the PWRGD pin one diode drop ( 0.7V) above the DRAIN pin. Transistor Q2 sinks the module's pull-up current and the module turns off. When the DRAIN voltage drops below VPG, Q3 will turn on, shorting the bottom of R7 to DRAIN and turning Q2 off. The pull-up current in the module then flows through R7, pulling the PWRGD pin high and enabling the module.
ACTIVE HIGH ENABLE MODULE 8 VDD R7 6.5k Q3 VEE GATE 6 R2 R3 C2 DRAIN 7 2x 1N4148 VIN- VOUT- PWRGD 1 VIN+ VOUT+
+
Q2 C3
ON/OFF
4
1640 F11
Q1
LT1640L/LT1640H
APPLICATIONS INFORMATION
When the DRAIN voltage of the LT1640L is high with respect to VEE, the internal pull-down transistor Q2 is off and the PWRGD pin is in a high impedance state (Figure 12). The PWRGD pin will be pulled high by the module's internal pull-up current source, turning the module off. When the DRAIN voltage drops below VPG, Q2 will turn on and the PWRGD pin will pull low, enabling the module. The PWRGD signal can also be used to turn on an LED or optoisolator to indicate that the power is good as shown in Figure 13.
GND GND 8 R4 3 R5 LT1640L UV VDD PWRGD Q2 VEE DRAIN VEE 4 * C1 3 - 48V * DIODES INC. SMAT70A 1 R1 2 4
1640 F12
(SHORT PIN)
2
+ -
OV
VPG
R6 SENSE 5 GATE 6 R2 R3 C2
Figure 12. Active Low Enable Module
GND GND R7 51k 5% PWRGD (SHORT PIN)
R4 562k 1% R5 9.09k 1% R6 10k 1%
3
UV LT1640L PWRGD
2
OV VEE 4 SENSE 5 GATE 6 DRAIN 7 1N4148 R2 R3 10 18k C2 5% 5% 3.3nF 100V Q1 IRF530
1640 F13
* R1 0.02 5% 1 2
3 - 48V * DIODES INC. SMAT70A
4
Figure 13. Using PWRGD to Drive an Optoisolator
1640lhfb
U
W
U
U
Gate Pin Voltage Regulation When the supply voltage to the chip is more than 15.5V, the GATE pin voltage is regulated at 13.5V above VEE. If the supply voltage is less than 15.5V, the GATE voltage will be about 2V below the supply voltage. At the minimum 10V supply voltage, the gate voltage is guaranteed to be greater than 6V. The gate voltage will be no greater than 18V for supply voltages up to 80V.
ACTIVE LOW ENABLE MODULE VIN+ 1 VOUT+
+ -
+
C3
ON/OFF
7 1N4148
VIN-
VOUT-
Q1
8 VDD 1
+
MOC207
C3 100F 100V
C1 150nF 25V
13
LT1640L/LT1640H
PACKAGE DESCRIPTION
0.300 - 0.325 (7.620 - 8.255)
0.009 - 0.015 (0.229 - 0.381)
(
+0.035 0.325 -0.015 8.255 +0.889 -0.381
)
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
14
U
N8 Package 8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
0.400* (10.160) MAX 8 7 6 5
0.255 0.015* (6.477 0.381)
1
2
3
4 0.130 0.005 (3.302 0.127)
0.045 - 0.065 (1.143 - 1.651)
0.065 (1.651) TYP 0.125 (3.175) 0.020 MIN (0.508) MIN 0.018 0.003 (0.457 0.076)
N8 1098
0.100 (2.54) BSC
1640lhfb
LT1640L/LT1640H
PACKAGE DESCRIPTION
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP
0.014 - 0.019 (0.355 - 0.483) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.016 - 0.050 (0.406 - 1.270)
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
S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 8 7 6 5
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
1
2
3
4
0.053 - 0.069 (1.346 - 1.752)
0.004 - 0.010 (0.101 - 0.254)
0.050 (1.270) BSC
SO8 1298
1640lhfb
15
LT1640L/LT1640H
TYPICAL APPLICATION
Using an EMI Filter Module Many applications place an EMI filter module in the power path to prevent switching noise of the module from being injected back onto the power supply. A typical application using the Lucent FLTR100V10 filter module is shown in Figure 14. When using a filter, an optoisolator is required to prevent common mode transients from destroying the PWRGD and ON/OFF pins.
R7 51k 5% (SHORT PIN) GND GND R4 562k 1% R5 9.09k 1% R6 10k 1% * 3 - 48V * DIODES INC. SMAT70A 1 8 VDD 3 UV 1 PWRGD DRAIN LT1640L 2 OV VEE 4 R1 0.02 5% 2 GATE SENSE 5 4 Q1 IRF530 C1 150nF 25V 6 7 1N4148 C2 3.3nF 100V VIN+ 1N4003 R3 18k 5% R2 10 5% C3 0.1F 100V VOUT+ C4 0.1F 100V LUCENT FLTR100V10 VIN- VOUT-
RELATED PARTS
PART NUMBER LTC 1421 LTC1422 LT1640A LT1641 LTC1642 LTC1643 LTC1645 LTC1646 LTC1647 LTC4211 LT4250 LTC4251
(R)
DESCRIPTION Dual Channel, Hot Swap Controller High Side Drive, Hot Swap Controller in SO-8 -48V Hot Swap Controller in SO-8 48V Hot Swap Controller Fault Protected Hot Swap Controller PCI Hot Swap Controller Dual Hot Swap Controller CompactPCI Hot Swap Controller Dual Hot Swap Controller Low Voltage Hot Swap Controller -48V Hot Swap Controller in SO-8 -48V Hot Swap Controller in SOT-23
TM
CompactPCI is a trademark of the PCI Industrial Computer Manufacturers Group
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507
q
U
MOC207 1 2
LUCENT JW050A1-E VIN+ ON/OFF VOUT+ SENSE + TRIM SENSE - VIN- 3
1640 F14
9 8 7 6
5V
+
+
C5 100F 100V
C6 0.1F 100V
C7 100F 16V
4
VOUT- CASE
5
CASE
Figure 14. Typical Application Using a Filter Module
COMMENTS Operates from 3V to 12V System Reset Output with Programmable Delay LT1640 Pin Compatible, Improved Drain Pin Ruggedness Foldback Analog Current Limit Operates Up to 16.5V, Protected to 33V 3.3V, 5V, 12V, - 12V Supplies for PCI Bus Operates from 1.2V to 12V, Power Sequencing 3.3V, 5V Supplies, 1V Precharge, Local PCI Reset Logic Dual ON Pins for Supplies from 3V to 15V 2.5V to 16.5V, Dual Level Circuit Breaker, Active Inrush Limiting LT1640 Pin Compatible, Active Current Limiting Active Current Limiting, Fast Circuit Breaker for Short-Circuit Faults
1640lhfb LT/TP 1101 1.5K REV B * PRINTED IN USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 1998

▲Up To Search▲

Price & Availability of LT1640L1

	To Download LT1640L1 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .