SMM151/152
Preliminary Datasheet
APPLICATIONS INFORMATION (CONTINUED)
FAULTS
Other codes will enable write protection. For example,
writing 59HEX will allow writes to the configuration
register but not to the memory, while writing 35HEX will
allow writes to the memory but not to the configuration
registers. The SMM151/152 also feature a Write
Protect pin (WP input) which, when asserted, prevents
writing to the configuration registers and EE memory.
In addition to these two forms of write protection there
is a configuration register lock bit which, once
programmed, does not allow the configuration registers
to be changed.
When either of the COMP1 or COMP2 inputs are in
fault, the open-drain FAULT# output will be pulled low.
A configuration option exists to disable the FAULT#
output while the device is margining. If “Fault Output
Disabled while Margining” is selected, Faults are
disabled for all margining except when margining to the
‘Off’ and ‘Nominal’ states. Also, the programmable
feature ‘Fault Holds Off and Shutdown Control’ is
enabled only for the Nominal margin state.
Fault Latched by a Fault Condition:
A2, A1, A0
The “Fault Latched by a Fault Condition” programmable
option is triggered only on the leading edge of a Fault.
That is, a latched fault can be cleared while the Fault
yet exists.
The address bits A[2:0] can be hard wired High or Low
or may be left open (High-Z) to allow for a total of 21
distinct device addresses. When floating, the inputs can
tolerate the amount of leakage as described by the
specification IAIT. An external 100k pull-up or pull down
resistor is sufficient to set a High or Low logic level.
Fault Latched by Ready I/O Pin:
Fault Latched by Ready I/O pin functions on the margin
transitions from Off to Hi/Low/Nominal or from Nominal
to Hi/Low or Hi/Low to Nominal but not from
Hi/Low/Nominal to Off.
WRITE PROTECTION
Write protection for the SMM151/152 is located in a
volatile register where the power-on state is defaulted
to write protect. There are separate write protect modes
for the configuration registers and memory. In order to
remove write protection, the code 55HEX is written to the
write protection register.
READY
+VIN 2.7V- 5.5V
FAULT#
12VIN
MUP
VDD
R6
MDN
VDD
0.01, 1%
VDD
C1
C2
0.1uF
C3
U2
0.01uF
10uF
DC-DC SIE
VDD
7
8
1
2
VOUT = 1.5V
+Vin
+Vout
+Vin
+Sense
11
9
Enable
+Vin
4
3
C12
R7
-Vout
Programming Supply
C Load
R Load
-Sense
U1
C10
C11
25
24
0.1uF
0.01uF
MDN
MUP
19
12
14
Comp1
Comp2
VM+
DIODE
D1
1
J1
1
SCL
SDA
28
SMM151
2
Gnd
SCL
SDA
MR
3
5
7
9
4
Gnd3
Rsrv5
6
6
4
2
8
15
20
26
10
A0
VM-
Trim
8
R5
2.5k
+10V Rsrv8
A1
10
+5V Rsrv10
A2
WP#
I2C
R1
R3
R2
VREF
CAPM+
7
Gnd
C7
0.1uF
C6
0.22uF
13
CAPM-
3
92227
R4
NCNCNCNC
C4
C5
C8
C9
0.01uF
1uF
0.01uF
0.47uF
Figure 6 – Typical application schematic shows the SMM151 controlling a 12V in/1.5V out DC/DC converter.
This example, using the 1.25V VREF, also shows the COMP1/2 pins monitoring the DC/DC converter VOUT set to an OV of 1.7V on
COMP1 and a UV of 1.3V on COMP2, the voltage divider resistors are: For OV, R1 = 1.37k, 1% R3 = 3.83k, 1%, For UV, R2 = 1.02k,
1% R4 = 25.5k, 1%. The Programming Supply jumper can be used to supply the SMM151 VDD voltage from the SMX3200
programmer when the device is programmed with board power off and the controlled supply unloaded.
Summit Microelectronics, Inc
2131 2.1 8/15/2008
13
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
