ISL25700 Datasheet, PDF (11/18 Pages) Intersil Corporation – Programmable Temperature Controlled MOSFET Driver

ISL25700
TABLE 1. ISL25700 MEMORY MAP
REGISTER NAME
REGISTER
BIT MAP
DEFAULT
ADDRESS 7
6
5
4
3
2
1
0 SETTINGS
Device ID (Read Only)
00h
ID[7] ID[6] ID[5] ID[4] ID[3] ID[2] ID[1] ID[0]
00h
Current Sense/
Coarse Temperature Control
01h
CS[4] CS[3] CS[2] CS[1] CS[0] CTC[2] CTC[1] CTC[0]
03h
Fine Temperature Control
02h
FTC[7] FTC[6] FTC[5] FTC[4] FTC[3] FTC[2] FTC[1] FTC[0]
80h
Gain Control (DAC Enable/
DAC Gain/System Loop Gain)
03h
DAC DAC
NA SLG[4] SLG[3] SLG[2] SLG[1] SLG[0]
90h
Enable Gain
General Purpose DAC
04h
DAC[7] DAC[6] DAC[5] DAC[4] DAC[3] DAC[2] DAC[1] DAC[0]
80h
General Purpose Register 1
05h
GP1[7] GP1[6] GP1[5] GP1[4] GP1[3] GP1[2] GP1[1] GP1[0]
00h
General Purpose Register 2
06h
GP2[7] GP2[6] GP2[5] GP2[4] GP2[3] GP2[2] GP2[1] GP2[0]
00h
R_INT Absolute Error (Read Only)
Control/Status Register
(Volatile Only)
07h
sign bit ERR[6] ERR[5] ERR[4] ERR[3] ERR[2] ERR[1] ERR[0]
XX
08h
NV
NA
NA
NA
NA
NA
NA BUSY
00h
Device ID Register (Reg.00h)
This is a read only register. It contains device ID code 00h.
Coarse Temperature Control (Reg.01h [2:0])
These 3 bits allow one to choose one of the seven coarse
windows for the temperature set point. The default set
point is about +59°C for the 100k R_TH thermistor with a
temperature coefficient of -4.25%/°C at +25°C, i.e.
Reg.01h[2:0] = 011b. The temperature set point can be
changed to any other set point within an operational
range from +40°C to +110°C, or use another type of
thermistor, including different resistance value or R/T
curve type (NTC slope), and then center the +15°C
coarse range temperature window on that new setting
based on the ratio of R_INT/R_TH according to Equation 1:
-_R----_T----_H-^R---₍-^I-_s-^N---_e--^T--_t-⁽-_p--^T--_o--⁾-_i--_n----_t--₎
=
K2 + K3 × ^C-----^o----^d----^e--
--------------------------------²---⁵---⁵-----
K1
(EQ. 1)
where:
R_INT - is an internal 9kΩ resistor, forming another leg of
the Wheatstone Bridge;
K1, K2 and K3 - are coefficients representing the ratio of
the current flowing through the legs of the Wheatstone
Bridge;
Code - is the decimal code in the Fine Temperature
Control register 02h.
The value of internal resistor R_INT can vary from part to
part and depends on the package temperature. The
actual R_INT at temperature T can be calculated using
Equation 2:
R_INT(T) = R_INT(25)x[1 + α(T – 25) + β(T – 25)²]
(EQ. 2)
where:
R_INT(25) = 9000 + R_INT abs. error x 15 - is internal
resistor value at +25°C in Ohms;
R_INT abs. error - is a signed integer value of absolute
error stored in Reg.07h[7:0] converted to a decimal
number; bit [7] represents a sign bit, 0 for “+” and 1 for
“-”;
α= –1337×10^–6 - 1st order temperature coefficient,
ppm/°C;
β= 5×10^–6
ppm/°C²;
- 2nd order temperature coefficient,
T - temperature in Celsius.
The K1, K2 and K3 coefficients and the thermistor value
range for each Coarse Temperature setting in
Reg.01h[2:0] should be taken according to Table 2.
TABLE 2. COARSE TEMPERATURE RANGE
THERMISTOR
Register
RESISTANCE RANGE
01h[2:0] K1 K2 K3 AT SET POINT (kΩ)
000
Do not use
001
3
3
2
5.4 to 9.0
010
4
3
2
7.2 to 12.0
100
5
3
2
9.0 to 15.0
011
7
3
2
12.6 to 21.0
101
8
3
2
14.4 to 24.0
110
9
3
2
16.2 to 27.0
111
12
3
2
21.6 to 36.0
Current Sense Threshold (Reg.01h [7:3])
This register sets the current limit trip point. When the
voltage applied to the I_SENSE pin falls below the
programmed voltage threshold, V_OUT goes high, thus
forming a negative feedback loop proportional to I_SENSE
x R_SENSE.
The value for this register should be taken according to
Table 3.
11
FN6885.0
September 3, 2010