Datasheet

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LTC1646

1646fa

■

CompactPCI Bus Removable Boards

■

Allows Safe Board Insertion and Removal from a

Live, CompactPCI

Bus

■

Controls 3.3V and/or 5V Supplies

■

Programmable Foldback Current Limit During

Power-Up

■

Dual Level Circuit Breakers Protect Supplies from

Overcurrent and Short-Circuit Faults

■

LOCAL_PCI_RST# Logic On-Chip

■

PRECHARGE Output Biases I/O Pins During Card

Insertion and Extraction

■

User Programmable Supply Voltage Power-Up Rate

■

15V High Side Drive for External N-Channel

MOSFETS

■

PWRGD, RESETOUT and FAULT Outputs

CompactPCI Dual

Hot Swap Controller

The LTC

1646 is a Hot Swap

controller that allows a

board to be safely inserted and removed from a live

CompactPCI bus slot. Two external N-Channel transistors

control the 3.3V and 5V supplies. The supplies can be

ramped-up in current limit or a programmable rate. Elec-

tronic circuit breakers protect both supplies against

overcurrent fault conditions. The PWRGD output indicates

when all of the supply voltages are within tolerance. The

OFF/ON pin is used to cycle the board power or reset the

circuit breaker. The PRECHARGE output can be used to

bias the bus I/O pins during card insertion and extraction.

PCI_RST# is logically combined on-chip with HEALTHY#

in order to generate LOCAL_PCI_RST# which can be used

to reset the CPCI card logic if either of the supply voltages

is not within tolerance.

The LTC1646 is available in the 16-pin narrow SSOP

package.

Figure 1

MMBT2222A

4.7nF

18Ω

12Ω

10Ω

2.7Ω

1.8Ω

10Ω

0.005Ω, 1%

0.007Ω

1k, 5%

10k

1.2k

PRECHARGE OUT

1V ±10%

OUT

= ± 55mA

SENSE

OUT

3.3V

RESET#

I/O

PCI

BRIDGE

(21154)

DATA BUS

V(I/O)

0.1µF 0.1µF

0.1µF

0.01µF

IRF7413

LOCAL_PCI_RST#

3.3V

7.6A

GATE

GND PRECHARGE DRIVE

RESETOUT

TIMER

OFF/ON

FAULT

PWRGD

RESETIN

LTC1646

891071211 5

613 14

BD_SEL#

HEALTHY#

PCI_RST#

1646 F01

DATA LINE EXAMPLE

COMPACT PCI

BACKPLANE

CONNECTOR

(MALE)

COMPACT PCI

CIRCUIT CARD

CONNECTOR

(FEMALE)

LONG 5V

3.3V

LONG 3.3V

GROUND

I/O PIN 1

Z1, Z2: BZX84C6V2

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

, LTC and LT are registered trademarks of Linear Technology Corporation.

Hot Swap is a trademark of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

Summary of content (20 pages)

PAGE 1
LTC1646 CompactPCI Dual Hot Swap Controller DESCRIPTIO U FEATURES ■ ■ Allows Safe Board Insertion and Removal from a Live, CompactPCITM Bus Controls 3.
PAGE 2
LTC1646 W W U W ABSOLUTE AXI U RATI GS U W U PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltages: 5VIN, 3VIN ............................................... 10V Input Voltages: (Pins 15, 16) ..................... –0.3V to 10V Output Voltages: (Pins 1, 3, 4) .................. –0.3V to 10V Analog Voltages and Currents: (Pin 9) .................................... –0.3V to (3VIN + 0.3V) (Pins 2, 5, 7, 11, 13, 14) ........ –0.3V to (5VIN + 0.3V) (Pin 10) ..................................................
PAGE 3
LTC1646 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. V5VIN = 5V and V3VIN = 3.3V unless otherwise noted. SYMBOL PARAMETER CONDITIONS VIH Input High Voltage OFF/ON, RESETIN, FAULT ● MIN 2 VTIMER TIMER Threshold Voltage VTIMER , FAULT = 0V ● 1.15 IIN OFF/ON Input Current OFF/ON = 5V OFF/ON = 0V RESETIN Input Current TYP MAX UNITS V 1.25 1.35 V ● ● ±0.08 ±0.
PAGE 4
LTC1646 U W TYPICAL PERFOR A CE CHARACTERISTICS 5VIN Undervoltage Lockout Voltage vs Temperature 3VIN Undervoltage Lockout Voltage vs Temperature 2.60 2.55 LOW-TO-HIGH TRANSITION 2.50 HIGH-TO-LOW TRANSITION 2.45 2.40 –50 –25 0 25 50 TEMPERATURE (°C) 75 60 LOW-TO-HIGH TRANSITION 2.55 HIGH-TO-LOW TRANSITION 2.50 2.45 2.40 –50 100 –25 0 25 50 TEMPERATURE (°C) 75 1646 G04 30 3VOUT = 0V 10 0 –50 –25 0 25 50 TEMPERATURE (°C) 75 58 57 56 55 54 53 52 51 –25 0 25 50 TEMPERATURE (°C) 75 21.
PAGE 5
LTC1646 U W TYPICAL PERFOR A CE CHARACTERISTICS Gate ISINK vs Temperature 15.5 3.00 FAULT = 0V POWER GOOD THRESHOLD VOLTAGE (V) 10 I = –1µA 5VIN = 5V 15.0 GATE VOLTAGE (V) 9 GATE ISINK (mA) Power Good Threshold Voltage vs Temperature (3VOUT) Gate Voltage vs Temperature 8 7 14.5 14.0 13.5 5VIN = 3.3V 6 13.0 5 –50 –25 0 25 50 TEMPERATURE (°C) 75 12.5 –50 100 –25 0 25 50 TEMPERATURE (°C) 75 1646 G13 2.90 2.85 2.80 –50 100 –25 0 25 50 TEMPERATURE (°C) 75 1646 G14 4.
PAGE 6
LTC1646 U W TYPICAL PERFOR A CE CHARACTERISTICS RESETOUT, PWRGD and FAULT Output Low Voltage vs ISINK 5VOUT/3VOUT Discharge Impedance vs Temperature 180 3VOUT/5VOUT DISCHARGE IMPEDANCE (Ω) 1.0 OUTPUT LOW VOLTAGE (V) 0.9 90°C 0.8 0.7 25°C 0.6 0.5 –45°C 0.4 0.3 0.2 0.1 0 0 1 2 3 ISINK (mA) 4 5 160 140 120 100 80 60 40 20 0 –50 –25 0 25 50 TEMPERATURE (°C) 1646 G22 75 100 1646 G23 U U U PI FU CTIO S RESETOUT (Pin 1): Open Drain Digital Output.
PAGE 7
LTC1646 U U U PI FU CTIO S 3VSENSE (Pin 9): 3.3V Current Limit Set. With a sense resistor placed in the supply path between 3VIN and 3VSENSE, the GATE pin voltage will be adjusted to maintain a constant voltage across the sense resistor and a constant current through the switch while the TIMER pin voltage is less than 1.25V. A foldback feature makes the current limit decrease as the voltage at the 3VOUT pin approaches GND. When the TIMER pin voltage is greater than 1.
PAGE 8
LTC1646 W TEST DIAGRA V3VONLY No 5V Input Mode Window Voltage V3VONLY = ⎟ 5VIN – 3VIN ⎢ 5VOUT = 3VOUT = 3.3V, 3VIN = 3.3V V3VONLY V5VIN 3.3V –V3VONLY 5V PWRGD 0V 1646 T01 W UW TI I G DIAGRA S tOC Overcurrent Fault Detect FALL TIME ≤ 1µs, 5VIN = 5V, 3VIN = 3.3V 5V V5VSENSE OR 3.3V 100mV OR V3VSENSE tOC FAULT 1V 1646 T02 tSC Short-Circuit Fault Detect FALL TIME ≤ 30ns, 5VIN = 5V, 3VIN = 3.3V 5V V5VSENSE OR 3.
PAGE 9
LTC1646 W BLOCK DIAGRA 5VIN 5VSENSE 12 11 GATE 10 VGG 5VOUT +– 3VIN 9 8 + 7 5 –+ 55mV 55mV +– – Q1 200µA –+ – + + – – 150mV +– 3VOUT 5VOUT 3VOUT 13µA + 3VSENSE Q2 Q3 150mV 2.5V UVL –+ 2.
PAGE 10
LTC1646 U W U U APPLICATIO S I FOR ATIO 4. Programmable foldback current limit: a programmable analog current limit with a value that depends on the output voltage. If the output is shorted to ground, the current limit drops to keep power dissipation and supply glitches to a minimum. 5. Dual-level, programmable 5V and 3.3V circuit breakers: this feature is enabled when the TIMER pin voltage exceeds 1.25V.
PAGE 11
LTC1646 U W U U APPLICATIO S I FOR ATIO GATE 10V/DIV GATE 10V/DIV 5VOUT 3VOUT 5V/DIV 5VOUT 3VOUT 5V/DIV TIMER 5V/DIV TIMER 5V/DIV BD_SEL# 5V/DIV BD_SEL# 5V/DIV HEALTHY# 5V/DIV LCL_PCI_RST# 5V/DIV HEALTHY# 5V/DIV LCL_PCI_RST# 5V/DIV PRECHARGE 5V/DIV PRECHARGE 5V/DIV 20ms/DIV 10ms/DIV 1646 F02 Figure 2. Normal Power-Up Sequence Power-Down Sequence When BD_SEL# is pulled high, a power-down sequence begins (Figure 3).
PAGE 12
LTC1646 U W U U APPLICATIO S I FOR ATIO Table 2. t TIMER vs CTIMER CTIMER tTIMER CTIMER tTIMER 0.01µF 2.5ms 0.22µF 55ms 0.022µF 5.5ms 0.33µF 82.5ms 0.033µF 8.25ms 0.47µF 118ms 0.047µF 11.8ms 0.68µF 170ms 0.068µF 17ms 0.82µF 205ms 0.082µF 20.5ms 1µF 250ms 0.1µF 25ms The TIMER pin is immediately pulled low when BD_SEL# goes high.
PAGE 13
LTC1646 U W U U APPLICATIO S I FOR ATIO Calculating RSENSE An equivalent circuit for one of the LTC1646’s circuit breakers useful in calculating the value of the sense resistor is shown in Figure 7. To determine the most appropriate value for the sense resistor first requires the maximum current required by the load under worst-case conditions.
PAGE 14
LTC1646 U W U U APPLICATIO S I FOR ATIO (RTOL = ±1%, ±2% or ±5%) and standard sense resistor values. Equation 7 can be used to calculate the nominal value from the maximum value found by Equation 6: RSENSE(NOM) = RSENSE(MAX) ⎛ RTOL⎞ 1+ ⎜ ⎟ ⎝ 100 ⎠ (7) Often, the result of Equation 7 may not yield a standard sense resistor value. In this case, two sense resistors with the same RTOL can be connected in parallel to yield RSENSE(NOM).
PAGE 15
LTC1646 U W U U APPLICATIO S I FOR ATIO Table 5. R1 and R2 Resistor Values vs Precharge Voltage VPRECHARGE R1 R2 VPRECHARGE 1.5V 18Ω 9.09Ω 1.4V 18Ω 1.3V 1.2V Other CompactPCI Applications R1 R2 0.9V 16.2Ω 1.78Ω 7.15Ω 0.8V 14.7Ω 3.65Ω 18Ω 5.36Ω 0.7V 12.1Ω 5.11Ω 18Ω 3.65Ω 0.6V 11Ω 7.15Ω 1.1V 18Ω 1.78Ω 0.5V 9.09Ω 9.
PAGE 16
LTC1646 U W U U APPLICATIO S I FOR ATIO COMPACT PCI COMPACT PCI BACKPLANE CIRCUIT CARD CONNECTOR CONNECTOR (MALE) (FEMALE) Z1 0.007Ω 5VIN 1 5V 3 LONG 5V 2 IRF7413 5VOUT 4 2.7Ω 10Ω BAV16W 1k 0.1µF 0.01µF 8 9 12 11 10 5 7 3VIN 3VSENSE 5VIN 5VSENSE GATE 5VOUT 3VOUT 6 GND GND LTC1646 Z1: BZX84C6V2 1646 F11 Figure 11. 5V Supply Only Typical Application If no 3.3V supply is present, Figure 11 illustrates how the LTC1646 should be configured.
PAGE 17
LTC1646 U W U U APPLICATIO S I FOR ATIO Since there is no bulk capacitance to damp the parasitic trace inductance, supply voltage transients excite parasitic resonant circuits formed by the power MOSFET capacitance and the combined parasitic inductance from the wiring harness, the backplane and the circuit board traces. These ringing transients appear as a fast edge on the 3.3V or 5V supply, exhibiting a peak overshoot to 2.
PAGE 18
LTC1646 U W U U APPLICATIO S I FOR ATIO In the majority of applications, it will be necessary to use plated-through vias to make circuit connections from component layers to power and ground layers internal to the PC board. For 1 ounce copper foil plating, a general rule is 1A of DC current per via, making sure the via is properly dimensioned so that solder completely fills any void. For other plating thicknesses, check with your PCB fabrication facility.
PAGE 19
LTC1646 U W U U APPLICATIO S I FOR ATIO Table 8. Manufacturers’ Web Site MANUFACTURER WEB SITE International Rectifier www.irf.com ON Semiconductor www.onsemi.com IRC-TT www.irctt.com Vishay-Dale www.vishay.com Vishay-Siliconix www.vishay.com Diodes, Inc. www.diodes.com U PACKAGE DESCRIPTIO GN Package 16-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641) .189 – .196* (4.801 – 4.978) .045 ±.005 16 15 14 13 12 11 10 9 .254 MIN .009 (0.229) REF .150 – .165 .
PAGE 20
LTC1646 U TYPICAL APPLICATIO CURRENT FLOW TO LOAD VIN 5V CURRENT FLOW TO LOAD SENSE RESISTOR SO-8 W D G D S D S D S R3 TRACK WIDTH W: 0.03" PER AMPERE ON 1 OZ Cu FOIL VOUT 5V W VIA R5 11 10 9 7 8 12 6 13 14 15 16 C1 5 4 3 2 1 LTC1646* CTIMER CURRENT FLOW TO SOURCE VIA TO GND W GND *ADDITIONAL DETAILS OMITTED FOR CLARITY DRAWING IS NOT TO SCALE! GND 1646 F15 Figure 15.