NX2116A MICROSEMI [Microsemi Corporation], NX2116A Datasheet

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NX2116A

Manufacturer Part Number
NX2116A
Description
SYNCHRONOUS PWM CONTROLLER WITH CURRENT LIMIT, POWER GOOD & OVER VOLTAGE
Manufacturer
MICROSEMI [Microsemi Corporation]
Datasheet
Rev. 3.0
03/14/06
The NX2116/2117 family of products are synchronous
Buck controller IC designed for step down DC to DC
converter applications. They are optimized to convert
bus voltages from 2V to 25V to as low as 0.8V output
voltage. The NX2116 and 2117 offer an Enable pin that
can be used to program the converter's start up voltage
using an external divider from bus voltage. These prod-
ucts operate at fixed internal frequency of 300kHz, ex-
cept that NX2116A operates at 600kHz and 2116B at
1MHz frequency. These products employ loss-less cur-
rent limiting protection by sensing the Rdson of syn-
chronous MOSFET followed by latch out feature. Feed-
back under voltage triggers Hiccup.
Other features are; 5V gate drive, Power good indica-
tor, Adaptive deadband control, Internal digital soft start;
Vcc undervoltage lock out and shutdown capability via
the enable pin or comp pin.
ON
OFF
NX2116CMTR
NX2116ACMTR
NX2117CUTR
NX2117ACUTR
NX2116BCMTR
R8
10k
Device
R7
10k
Vin2
+12V
+5V
Vin1
2N3904
39uF
C3
CURRENT LIMIT, POWER GOOD & OVER VOLTAGE
68k
Temperature
12.4k
R5
R6
DESCRIPTION
0 to 70
0 to 70
0 to 70
0 to 70
0 to 70
33pF
C1
1uF
C4
17.4k
R3
10
C2
1.5nF
16k
R4
R2
Figure 1 - Typical application of 2116
SYNCHRONOUS PWM CONTROLLER WITH
o
o
o
o
o
C
C
C
C
C
11
6
8
7
Comp
EN
Gnd
Fb
Vcc
4
NX2116/2116A/2116B/2117/2117A
MLPD-10L
MLPD-10L
MLPD-10L
MSOP-10L
MSOP-10L
Package
2.61k
L2 1uH
R9
R1
Pgood
BST
1
Hdrv
OCP
20k
n
n
n Fixed 300kHz, 600kHz and 1MHz for NX2116 and
n Internal Digital Soft Start Function
n Less than 50 nS adaptive deadband
n Enable pin to program BUS UVLO for NX2116/2117
n
n
n
n
n
n
Ldrv
SW
1nF
C8
D1
MBR0530T1
300kHz, 600kHz for NX2117 family.
10
2
Bus voltage operation from 2V to 25V
Power Good indicator available in NX2116
Programmable current limit triggers latch out by
sensing Rdson of
Synchronous MOSFET
No negative spike at Vout during startup and
shutdown
Graphic Card on board converters
Memory Vddq Supply
On board DC to DC such as 2V to 3.3V, 2.5V or
1.8V
ADSL Modem
3
5
9
R10
R11
1k
3.7k
ORDERING INFORMATION
C7
0.1uF
+5V
TYPICAL APPLICATION
Frequency
300kHz
600kHz
1MHz
300kHz
600kHz
M1
M2
C5
1uF
L1 1uH
PRELIMINARY DATA SHEET
APPLICATIONS
270uF,18mohm
Cin
Co
2x (220uF,12mohm)
Pb Free Product
Pb-Free
FEATURES
Yes
Yes
Yes
Yes
Yes
Vout
+1.8V,9A
1

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NX2116A Summary of contents

Page 1

... These prod- ucts operate at fixed internal frequency of 300kHz, ex- cept that NX2116A operates at 600kHz and 2116B at 1MHz frequency. These products employ loss-less cur- rent limiting protection by sensing the Rdson of syn- chronous MOSFET followed by latch out feature ...

Page 2

ABSOLUTE MAXIMUM RATINGS VCC to GND & BST to SW voltage .................... -0.3V to 6.5V BST to GND Voltage ........................................ -0.3V to 35V SW to GND ...................................................... -2V to 35V All other pins .................................................... -0.3V to VCC+0.3V or 6.5V Storage ...

Page 3

... Rev. 3.0 03/14/06 NX2116/2116A/2116B/2117/2117A SYM Test Condition _UVLO V Rising _Hyst V Falling 2116, 2117 S 2116A,2117A 2116B V RAMP Ib Tss NX2116,NX2117 NX2116A, NX2117A NX2116B (Hdrv) I=200mA source (Hdrv) I=200mA sink V -V =4.5V BST =4.5V BST SW Ldrv going Low to Hdrv going H) High, 10%-10% (Ldrv) I=200mA source R (Ldrv) ...

Page 4

PIN DESCRIPTIONS PIN SYMBOL Power supply voltage. A high freq 1uF ceramic capacitor is placed as close as possible to and connected to this pin and ground pin. The maximum rating of this pin is 5V. VCC This pin supplies ...

Page 5

BLOCK DIAGRAM VCC 1.25V Bias Generator 0.8V EN 1.25/1.15 START 0.8V OSC Digital ramp start Up FB COMP START GND Figure 2 - Simplified block diagram of the NX2116 Rev. 3.0 03/14/06 NX2116/2116A/2116B/2117/2117A FB 0.6V UVLO POR START OC PWM ...

Page 6

... Input voltage Output voltage OUT I - Output current OUT DV - Output voltage ripple RIPPLE F - Working frequency Inductor current ripple RIPPLE Design Example The following is typical application for NX2116A, the schematic is figure 12V IN V =1.8V OUT F =600kHz S I =9A OUT DV <=20mV RIPPLE DV < ...

Page 7

Usually when this type of capacitors are selected, the amount of capaci- tance per single unit is not sufficient to meet the tran- sient ...

Page 8

It should be considered that the proposed equa- tion is based on ideal case, in reality, the droop or over- shoot is typically more than the calculation. The equa- tion gives a good start. For more margin, more capaci- tors ...

Page 9

Case 1: F <F < ESR power stage F LC 40dB/decade loop gain F ESR 20dB/decade compensator Figure 4 - Bode plot of Type III compensator Design example for type ...

Page 10

Case 2: F <F <F LC ESR O power stage F LC 40dB/decade F ESR loop gain 20dB/decade compensator Figure 5 - Bode plot of Type III compensator (F <F <F ) ...

Page 11

B. Type II compensator design If the electrolytic capacitors are chosen as power stage output capacitors, usually the Type II compensa- tor can be used to compensate the system. Type II compensator can be realized by simple RC circuit without ...

Page 12

R value by the following equation OSC ESR m 1.5V 2 60kHz 1uH = 12V 6.5m 1.8V 0.8V =8.15k Choose R =8. Calculate ...

Page 13

HCON OUT DS(ON LCON OUT DS(ON TOTAL HCON LCON where the R will increases as MOSFET junc- DS(ON) tion temperature increases dependency. ...

Page 14

I OCP 40uA OCP R OCP comparator Figure 10 - Over current protection The over current limit can be set by the following equation I R OCP OCP I SET K R DSON If MOSFET R =6.5m , the worst ...

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