SMM151/152

Preliminary Datasheet

Summit Microelectronics, Inc

2131 2.1 8/15/2008

13

FAULTS

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:

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.

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

write protection register.

Other codes will enable write protection. For example,

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.

A2, A1, A0

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

resistor is sufficient to set a High or Low logic level.

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.

C4

0.47uF

FAULT#

READY

VOUT = 1.5V

R6

0.01, 1%

VDD

R1

R2

R3

R4

+Vout

1

+Sense

2

-Sense

3

-Vout

4

+Vin

7

+Vin

8

+Vin

9

Enable

11

U2

DC-DC SIE

C8

0.01uF

C9

0.01uF

MUP

C3

10uF

C12

C Load

C1

0.01uF

C10

0.1uF

C11

0.01uF

VDD

MDN

C2

0.1uF

SCL

1

A2

2

NC

3

A1

4

A0

6

Gnd

7

WP#

8

NC

9

CAPM+

10

Comp2

12

NC

22

VM+

14

NC

27

CAPM-

13

Comp1

19

Trim

20

VM-

15

MUP

24

MDN

25

VREF

26

SDA

28

U1

SMM151

R7

R Load

Gnd

1

SCL

2

Gnd3

3

SDA

4

Rsrv5

5

MR

6

+10V

7

Rsrv8

8

+5V

9

Rsrv10

10

J1

I2C

Programming Supply

12VIN

+VIN 2.7V- 5.5V

VDD

R5

2.5k

C6

0.22uF

VDD

C5

1uF

C7

0.1uF

D1

DIODE

APPLICATIONS INFORMATION (CONTINUED)