ST STLM20 User Manual

Ultra-low current 2.4 V precision analog temperature sensor

Features

■ Precision analog voltage output temperature

sensor

■ ±1.5 °C maximum temperature accuracy

at 25 °C (±0.5 °C typical)

■ Ultra-low quiescent supply current:

4.8 µA (typ) and 8.0

■ Operating voltage range: 2.4 V to 5.5 V

■ Operating temperature range:

–55 °C to 130 °C (grade 7)
–40 °C to 85 °C (grade 9)

■ SOT323-5L 5-lead package

■ UDFN-4L 4-lead package

Applications

µA (max)

STLM20

SOT323-5L

■ Smartphones

■ Multimedia PDA devices

■ GPS devices

■ Portable medical instruments

■ Voltage-controlled crystal oscillator

temperature monitors

■ RF power transistor monitor

UDFN-4L

July 2010 Doc ID 12495 Rev 13 1/19

www.st.com

1

Contents STLM20

Contents

1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Transfer function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4 DC and AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

5 Capacitive load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6 Typical operating characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

8 Part numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2/19 Doc ID 12495 Rev 13

STLM20 List of tables

List of tables

Table 1. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Table 2. First order equations optimized for different temperature ranges . . . . . . . . . . . . . . . . . . . . . 6

Table 3. Second order parabolic equation (V
Table 4. Second order parabolic equation for operation over the full voltage range

(V

= 2.4 V to 5.5 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Table 5. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Table 6. DC and AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Table 7. Resistor/capacitor combinations for the filter network . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Table 8. SOT323-5L – 5-lead small outline transistor package mechanical data. . . . . . . . . . . . . . . 13

Table 9. UDFN-4L – 4-lead (1.00 mm x 1.30 mm) package mechanical data . . . . . . . . . . . . . . . . . 14

Table 10. Carrier tape dimensions for SOT323-5L and UDFN-4L packages . . . . . . . . . . . . . . . . . . . 15

Table 11. Reel dimensions for 8 mm carrier tape - SOT323-5L and UDFN-4L packages . . . . . . . . . 16

Table 12. Ordering information scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Table 13. Marking description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Table 14. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

CC

= 2.7 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

CC

Doc ID 12495 Rev 13 3/19

List of figures STLM20

List of figures

Figure 1. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 2. Connections (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 3. Filter network for noisy environments or capacitive loads > 300 pF . . . . . . . . . . . . . . . . . . 10

Figure 4. V

Figure 5. SOT323-5L – 5-lead small outline transistor package outline . . . . . . . . . . . . . . . . . . . . . . 13

Figure 6. UDFN-4L – 4-lead (1.00 mm x 1.30 mm) package outline . . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 7. Carrier tape for SOT323-5L and UDFN-4L packages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 8. Reel schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

vs. temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

OUT

4/19 Doc ID 12495 Rev 13

STLM20 Description

1 Description

The STLM20 is a precision analog output temperature sensor for low current applications
where maximizing battery life is important. It operates over a –55 °C to 130 °C (grade 7) or
–40 °C to 85 °C (grade 9) temperature range. The power supply operating range is 2.4 V to

5.5 V. The maximum temperature accuracy of the STLM20 is ± 1.5 °C (±0.5 °C typ) at an
ambient temperature of 25 °C and V
and reaches a maximum of ±2.5 °C at the temperature range extremes. The temperature
range is affected by the power supply voltage. For the temperature grade 7 device, a power
supply voltage of 2.7 V to 5.5 V, the temperature range extremes are +130 °C and –55 °C
(decreasing the power supply voltage from 2.7 V to 2.4 V changes the low end of the
operating temperature range from –55 °C to –30 °C, while the positive remains at +130 °C).

The STLM20 has a maximum quiescent supply current of 8 µA. Therefore, self-heating is
negligible.

Figure 1. Logic diagram

of 2.7 V. The temperature error increases linearly

CC

V

CC

STLM20

(1)

GND

1. Pin 2 GND may be grounded or left floating (SOT323-5L only). For optimum thermal conductivity to the PC
board ground plane, it should be grounded.

Table 1. Signal names

V

CC

Supply voltage

V

OUT

AI12252

GND Ground

V

OUT

Output voltage

NC No connect

Figure 2. Connections (top view)

NC

GND

V

OUT

(1)

(2)

1

5

2

3

4

SOT323-5L

GND

V

CC

AI12253

V

NC

OUT

(1)

1

2

UDFN-4L

4

3

V

CC

GND

AI12253_a

1. Pin 1 NC should be left floating or grounded.

2. Pin 2 GND may be grounded or left floating. For optimum thermal conductivity to the PC board ground
plane, it should be grounded.

Doc ID 12495 Rev 13 5/19

Transfer function STLM20

2 Transfer function

The STLM20’s transfer function can be described in different ways, with varying levels of
precision. A simple linear transfer function, with good accuracy near 25 °C is expressed as:

Equation 1 (first order linear equation)

V

11.69m V–()°CT1.8663+×⁄ V=

O

Over the specified operating temperature range, the best accuracy can be obtained by using
the parabolic transfer function:

Equation 2 (second order parabolic equation)

O

−

2–26

8639.1)T1015.1(–)T1088.3(–V

+××+××=

and solving for T:

()

6

101962.296.1481–T

+×+=

V8639.1

−

O

6–

1088.3

×

The best fit linear transfer function for many popular temperature ranges was calculated in

Ta bl e 2 , where the error introduced by the linear transfer function increases with wider

temperature ranges.

Table 2. First order equations optimized for different temperature ranges

Temperature range

T

min

(°C) T

max

(°C)

Linear equation

VO =

Maximum deviation of linear

equation from parabolic equation

(°C)

–55 130 –11.79 mV/°C * T + 1.8528 V ±1.41

–40 110 –11.77 mV/°C * T + 1.8577 V ±0.93

–30 100 –11.77 mV/°C * T + 1.8605 V ±0.70

–40 85 –11.67 mV/°C * T + 1.8583 V ±0.65

–10 65 –11.71 mV/°C * T + 1.8641 V ±0.23

35 45 –11.81 mV/°C * T + 1.8701 V ±0.004

20 30 –11.69 mV/°C * T + 1.8663 V ±0.004

6/19 Doc ID 12495 Rev 13