MIC2596/2597
Micrel
MIC2596/2597
Dual Channel Negative Voltage Hot Swap Controllers
Final Information
General Description
The MIC2596 and MIC2597 are dual channel negative volt-
age hot swap controllers designed to facilitate safe PC board
insertion into and removal from live backplanes. To minimize
external components, each channel of the MIC2596/MIC2597
has an integrated high voltage power MOSFET. Built-in
current sensing in each channel provides inrush current
limiting, by regulating the channel’s output current to a user-
settable maximum. Current sensing also provides program-
mable overcurrent and open-load detection. A channel will
be turned off if it experiences overload or no-load conditions
lasting longer than programmable intervals. Foldback cur-
rent limiting holds power dissipation of the internal MOSFETs
at safe levels during overloads, and very fast shutdown
response to faults ensures protection for both system power
supplies and the load. The MIC2596 will automatically
attempt to restart into an overcurrent fault until the fault is
cleared, while the MIC2597 will latch the output in the off state
until it is reset by external action. A logic-compatible signal
is provided on each channel to indicate overcurrent or under-
current fault conditions.
Features
•
•
•
•
•
•
•
•
•
Allows safe hot-swap in –48V systems
Operates to –70V
Programmable inrush current limiting
Two thermally isolated channels
Overcurrent fault sensing and protection
Nuisance trip prevention circuitry
Open-load detection
Logic compatible Enable and Fault signals
Separate analog and logic ground pins support large
system ground differentials (±8V)
Applications
• Central Office Switching
• –48V Power Distribution
Typical Application
C
L
6
VDDA
+3.3V
R
PU
V
CC
FAULT#_CH1
FAULT#_CH2
CONTROLLER
ON/OFF_CH1
ON/OFF_CH2
GND
15
20
11
5
VCLAMP
OUT1
ILIMIT
19
V
OUT1
R
PU
FAULT#1
FAULT#2
ON1
ON2
VDDL
CTIMER1
CTIMER2
MIC2596
2
CGATE1
17
C
L
C1
R1
1
10
OUT2
CGATE2
12
V
OUT2
3
14
8
ILIMIT2
4
9
C2
C3
C5
COL1
C4
COL2
7
VEE
16
R2
C6
V
IN
–48V
System-Controlled Hot Swap
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
April 2001
1
MIC2596/2597
MIC2596/2597
Micrel
Ordering Information
Part Number
MIC2596-1BTS
MIC2596-2BTS
MIC2597-1BTS
MIC2597-2BTS
MIC2596-1BTSE
MIC2596-2BTSE
MIC2597-1BTSE
MIC2597-2BTSE
ON Signal
Active-High
Active-Low
Active-High
Active-Low
Active-High
Active-Low
Active-High
Active-Low
Circuit Breaker Function
Auto-Retry
Auto-Retry
Latched Off
Latched Off
Auto-Retry
Auto-Retry
Latched Off
Latched Off
Package
20 pin TSSOP
20 pin TSSOP
20 pin TSSOP
20 pin TSSOP
20 pin Exposed Pad
TSSOP
20 pin Exposed Pad
TSSOP
20 pin Exposed Pad
TSSOP
20 pin Exposed Pad
TSSOP
MIC2596/2597
2
April 2001
MIC2596/2597
Micrel
Pin Configuration
ON1 1
ILIMIT1 2
CTIMER1 3
COL1 4
VCLAMP 5
VDD/VDDA* 6
COL2 7
CTIMER2 8
ILIMIT2 9
ON2 10
20 FAULT#1
19 OUT1
18 N/C
17 CGATE1
16 VEE
15 VDDL*
14 CGATE2
13 N/C
12 OUT2
11 FAULT#2
20-Pin TSSOP
Pin Descriptions
Pin Number
20, 11
1, 10
Pin Name
FAULT1#/FAULT2#
ON1/ON2
Pin Function
Fault Status Output, Active-low - Asserted when the circuit breaker trips
upon overcurrent, open-load or thermal shutdown conditions.
Enable Input - Active-high (MIC259x-1) or active-low (MIC259x-2). When
asserted ON will initiate a start cycle by activating the GATE output. Tog-
gling ONx will also reset the circuit breaker in the MIC2597.
Current Limit Response Timer. A capacitor connected to this pin defines the
period of time t
FLT
in which an overcurrent event must last to signal a fault
condition and turn the output off.
Negative Supply Voltage Input.
Current Limit Set. The current limit threshold is set by connecting a resistor
between this pin and V
EE
. When the current limit threshold of a channel is
exceeded for t
FLT
the circuit breaker for that channel is tripped and its
respective output is immediately shut off.
Switch Outputs. Connect to load.
Positive Supply Input. Normally connected as the power ground reference in
negative supply (–48V) systems. V
DDA
is the IC’s “analog ground,” used for
internal biasing relative to –V
EE
.
FAULT# Clamp Voltage. A small bias current into this pin (usually supplied
by the controlling logic’s supply voltage) powers internal circuitry which
establishes the active low voltage of the FAULT# signals. In normal circuit
configurations, the low-level output voltage will be clamped to V
DDL
.
Open-Load Detect Timer - When the load current falls below 8% of full scale
current limit the capacitor connected to C
OL1
/C
OL2
begins to change. When
the voltage across C
OL1
/C
OL2
rises above 1.32V the output is immediately
shut off. When ONx is deasserted or when the load current is above 15% of
full scale current limit then this pin is held to V
EE
. Tying this pin to V
EE
will
disable this function.
Noise filtering capacitors for the gates of the main output MOSFETs.
Typically in the range of 1000pF ~ 4700pF.
V
DDL
provides the ground reference for the logic-compatible FAULT# and
ON signals, while accommodating
±8
volts of ground differential between the
controlling logic and the power ground (V
DDA
) of the MIC2596/2597. If no
differential voltage capability is required between V
DDA
and V
DDL
, these two
pins should be tied together at the part.
No Connect.
3, 8
CTIMER1/CTIMER2
16
2, 9
V
EE
ILIMIT1/ILIMIT2
19, 12
6
OUT1/OUT2
VDDA
5
VCLAMP
4, 7
COL1/COL2
17,14
15
CGATE1/CGATE2
VDDL
13, 18
N/C
April 2001
3
MIC2596/2597
MIC2596/2597
Micrel
Absolute Maximum Ratings
(All voltages are referred to V
EE
) (Note 1)
Supply Voltage (V
DDA
to V
EE
) ........................ –0.3V to 80V
Supply Voltage (V
DDL
to V
EE
) ........................ –0.3V to 80V
V
CLAMP
pin (Note 2) ...................................... –0.3V to 5.5V
ON, FAULT# pins (Note 2) ............................ –0.3V to 5.5V
Junction Temperature .............................. Internally Limited
ESD (Human Body Model) ........................................... [tbd]
ESD (Machine Model) .................................................. [tbd]
Operating Ratings
Supply Voltage (V
DDA
to V
EE
) ........................... 15V to 70V
Supply Voltage (V
DDL
to V
EE
) ........................... 15V to 70V
V
CLAMP
(relative to V
DDL
) .............................. 2.5V to 5.25V
Ambient Temperature ................................ –40°C to +85°C
TSSOP Package: ..........................................
θ
JA
= 90°C/W
TSE Exposed Pad Package (Note 3) ............
θ
JA
= 38°C/W
Continuous Junction Temperature ........... 125°C Maximum
Electrical Characteristics
V
DDA
= V
DDL
= 40V, V
EE
= 0V, V
CLAMP
= V
DD
+ 3.3V, R
LIMIT1
= R
LIMIT2
= 20k , T
A
= 25°C unless otherwise noted.
Symbol
I
DD
UVLO
Parameter
Supply Current
Undervoltage Lockout threshold
Undervoltage Lockout hysteresis
I
CLAMP
V
OL
R
DSON
CLF
I
OFF
CLAMP pin supply current
FAULT#[1/2] output low voltage
(Note 2)
On-Resistance (Each Switch)
On-Resistance (Each Switch)
Current Limit Factor (Notes 4, 6)
Off-state Output leakage current
Off-state Output leakage current
I
TIMER
I
OLDTH
Overcurrent Timer pull-down current
Overcurrent Timer charge current
Open Load Detect threshold
(percent of full-scale output current)
(Notes 5, 6)
I
OLDHYS
V
THHI
V
THLO
Open Load Detect hysteresis
(percent of full-scale output current)
Overload Timer Capacitor
high-going threshold voltage
Overload Timer low -going threshold
voltage for auto-restart (MIC2596)
(Note 6)
C
GATE
Capacitor charge current
Open Load Detect Timer high-going
threshold voltage
Open-Load Detect Timer capacitor
charge current
Output voltage foldback threshold
Upper threshold
Lower threshold
Foldback output current limit
V
OUT
– V
EE
> V
FBU
, % of full scale
current limit
During turn-on
1.12
–10
25
10
12
1.12
0.21
I
OUT
decreasing
I
OUT
increasing
Condition
V
DDA
= V
DDL
= 70V, Both outputs on or off
–40°C to 85°C
V
IN
rising
V
IN
falling
FAULT#1 and FAULT#2 are high
V
CLAMP
= 5.25V
I
OL
= 250µA
T
J
= 25°C
T
J
= 85°C
R
LIMIT1
= R
LIMIT2
= 40k
Switch is off, T
J
= 25°C
V
OUT
= V
DDA
= V
DDL
= 70V
Switch is off, T
J
= 85°C
V
OUT
= V
DDA
= V
DDL
= 70V
1.1
–42
6
8
1.9
–72
9
12
3
1.32
0.24
1.52
0.27
1700
–0.3
11.5
–0.35
190
–0.18
1.5
1.9
2000
0.4
2.0
2.5
2300
2
5
2.7
–103
12
16
Min
Typ
3.3
Max
5.0
12.5
Units
mA
V
V
µA
V
Ω
Ω
A•Ω
µA
µA
µA
µA
%
%
%
V
V
I
GATE
V
COL
I
COL
V
FBU
V
FBL
I
FOLDBACK
–79
1.32
–17
31
13
20
1.52
–24
37
16
28
µA
V
µA
V
V
%
MIC2596/2597
4
April 2001
MIC2596/2597
Symbol
V
IL
I
IL
V
IH
T
PROTECT
Parameter
ON Pin Low threshold Voltage
ON Pin input current
ON Pin High threshold voltage
Thermal self-protection points
Condition
–40°C to 85
°C
V
ON
= V
CLAMP
–40°C to 85°C
T
J
increasing (turn-off)
T
J
decreasing (turn-on)
AC Parameters
t
ON
t
OFF
t
R
t
F
t
OC
t
OFF(UVLO)
Notes:
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Micrel
Min
Typ
Max
0.8
150
2.0
145
135
Units
V
µA
V
°C
°C
Turn-on time
Turn-off time
Rise-time
Fall-time
Current limit response time
Undervoltage to OUT1/OUT2 off
response time
C
L
= 1µF, R
L
= 1kΩ, C
GATE
= 1nF
C
L
= 1µF, R
L
= 1kΩ, C
GATE
= 1nF
C
L
= 1µF, R
L
= 1kΩ, C
GATE
= 1nF
C
L
= 1µF, R
L
= 1kΩ, C
GATE
= 1nF
C
GATE
≤
1nF
C
L
= 1µF, R
L
= 1kΩ, C
GATE
= 1nF
[tbd]
[tbd]
[tbd]
[tbd]
4
[tbd]
ms
ms
ms
ms
µs
µs
Absolute Maximum Ratings are those ratings beyond which a part may be permanently damaged. Functionality is not guaranteed when a part
is operated at its Absolute Maximum Ratings.
Relative to V
DDL
.
The exposed pad of the TSE package must be connected to V
EE
of the part, or be electrically isolated.
The current limit threshold is defined by the current limit factor divided by R
LIMIT
, the resistor connected to the I
LIMIT1
/I
LIMIT2
pins.
Open Load Detect is not guaranteed to function for programmed maximum output currents <[tbd]mA
Final production value TBD.
Timing Diagrams
Device Under
Test
OUT
R
L
V
OUT
t
R
C
L
V
OUT
90%
10%
90%
10%
t
F
ON/OFF
50%
t
ON
90%
t
OFF
10%
MIC2596-1
MIC2597-1
ON/OFF
50%
t
ON
90%
t
OFF
10%
MIC2596-2
MIC2597-2
V
OUT
V
OUT
April 2001
5
MIC2596/2597
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