ncp5890 ON Semiconductor, ncp5890 Datasheet - Page 4

• Manufacturer Part Number: ncp5890
• Description: Light Management Ic Dedicated For Lcd Backlighting And Multi-led Fun Light Applications
• Manufacturer: ON Semiconductor

1. Using low ESR ceramic capacitor and low ESR inductor is mandatory to optimize the DC/DC efficiency
PIN DESCRIPTIONS
PIN
10
12
13
14
15
16
11
1
2
3
4
5
6
7
8
9
I2CADR
AGND
PWM3
PWM2
PWM1
PGND
AMBS
Name
VBAT
SCL
SDA
VSB
I
Vos
I
REF
FB
Lx
PK
OUTPUT,
POWER,
OUTPUT
ANALOG
ANALOG
ANALOG
ANALOG
ANALOG
ANALOG
ANALOG
DIGITAL
DIGITAL
DIGITAL
POWER
POWER
POWER
POWER
POWER
INPUT,
INPUT,
INPUT,
INPUT,
INPUT,
INPUT,
INPUT,
INPUT,
INPUT,
INPUT,
INPUT,
Type
This pin carries the I2C clock to control the DC/DC converter and is used to set up the output cur-
rent and the photo sensor. The SCL clock is associated with the SDA signal.
This pin carries the data provided by the I2C protocol. The content of the SDA byte is used to pro-
gram the mode of operation and to set up the output current.
This pin is used to select the I2C address of the NCP5890:
In order to avoid any risk during the operation, the digital levels are intended to be hardwired prior to
power up the system.
This pin provides a switched voltage, derived from the Vbat supply, to bias the external photo sense.
The current capability of this voltage is 2 mA.
The VSB pin is disconnected when the Shutdown mode has been engaged.
This pin senses the voltage developed across the external Photo Bias resistor. Since this is a very
high impedance input, care must be observed to minimize the leakage current and the noise that
may influence the photo sense analog function. The bias parameters associated with the AMBS pin
are reloaded when the chip resumes from Shutdown to Normal operation.
This pin provides the inductor peak current during normal operation. In no case shall the voltage at
I
This pin provides the reference current, based on the internal band−gap voltage reference, to con-
trol the output current flowing in the LED. A 1% tolerance, or better, resistor shall be used to get the
highest accuracy of the LED biases. An external current source can be used to bias this pin to dim
the light coming out of the LED.
In no case shall the voltage at I
by the internal reference.
This pin is the GROUND signal for the analog and digital blocks and must be connected to the sys-
tem ground. A ground plane is strongly recommended.
This pin is the current sense of the series arranged LED. The built−in current mirror will automatic-
ally adapt the voltage drop across this pin (typically 400 mV).
This pin provides a PWM control of the LED connected between PWM3−FB. The PWM is pro-
grammed by the I2C port and preset to zero upon power ON.
This pin provides a PWM control of the LED connected between PWM2. The PWM is programmed
by the I2C port and preset to zero upon power ON.
This pin provides a PWM control of the LED connected between PWM1. The PWM is programmed
by the I2C port and preset to zero upon power ON.
The external inductor shall be connected between this pin (drain of the internal Power switch) and
Vbat. The voltage is internally clamped at 34 V under worst case conditions. The external Schottky
diode shall be connected as close as possible to this pin. See Note 1 for ESR recommendations.
This pin is the GROUND reference for the DC/DC converter and the output current control. The pin
must be connected to the system ground, a ground plane is strongly recommended.
Input Battery voltage to supply the analog , the digital blocks and the main Power switch driver. The
pin must be decoupled to ground by a 10 mF ceramic capacitor.
This pin senses the output voltage supplied by the DC/DC converter. The Vos pin must be by-
passed by 1.0 mF/50 V ceramic capacitor located as close as possible to the pin to properly bypass
the output voltage to ground. The circuit will not operate without such bypass capacitor connected to
the Vos pin.
The output voltage is internally clamped to 34 V maximum in the event of a no load situation.
PK
I2CADR = Low ³ address = %0111 0010 = $72
I2CADR = High ³ address = %0111 0100 = $74
pin be forced either higher or lower than the 1144 mV provided by the internal reference.
http://onsemi.com
4
REF
pin be forced either higher or lower than the 1144 mV provided
Description