RESISTORS

PRODUCT SELECTION GUIDE

TT Electronics plc is a global electronics company.

Within its resistors business unit are multiple manufacturing facilities and

dedicated engineering teams providing custom solutions.

BI Technologies, IRC and Welwyn are market leading brands within this group, with an 80-year track record of resistive component

innovation.

TT Electronics offers the full spectrum of resistor technologies and a broad standard product range, in addition to providing custom

engineered solutions.

Medical Application

A manufacturer of portable automatic external debrillators (AEDs) needed a

compact high voltage resistor for use in the charge regulation circuit. Standard

products from other sources were proving unreliable under conditions of sustained

high humidity and high voltage loading. The precision and stability with time and

temperature were critical as they directly impact the tight error budget for delivered

energy dosage. TT Electronics engineers solved this problem with a planar resistor

with optimised thick-lm element design and a high integrity epoxy coating and

supported the customer through their rigorous approval process.

Other innovations in this area include pulse withstanding chip resistors for monitor

circuit protection and a 200J energy dump resistor based on reinforced wirewound

technology to enable daily self-test diagnostic cycles.

Aerospace Application

A designer working on an anti-ice aircraft surface heating system had to meet

stringent safety requirements in the event of failure of a heating circuit. The failure

mode to be mitigated was an “always on” condition, and this called for a single shot

disconnection switch. TT Electronics engineers were contacted to help identify a

solution, but nothing was available off the shelf. A set of potential solutions was

proposed and the preferred option was a combination of self-switching resistive

heater and thermal fuse. This was developed from concept into a fully qualied

component within the required timescale. The compact format of the design also

contributed signicantly to the customer’s mass reduction target.

Consumer Application

Safety is becoming increasingly important in consumer products and a key

aspect is protection against re by the use of fusing line input resistors. With

one component it is possible to reduce inrush current, protect against power line

surges and give flameproof circuit opening under fault conditions. One company

working in this area had a further need for fusing to be inaudible and invisible to

the consumer.

TT Electronics devised a solution using a wirewound resistor with impact absorbing

coating which contains the fused element without fragmenting. Other innovations

include the offer of UL1412 recognised fusing resistors.

Resistors

Industrial Application

High-end industrial circuit breakers need to give reliable long-term performance

under harsh conditions. In particular, transient surges caused by switching of

inductive loads present a challenge. When a designer of industrial circuit breakers

needed to modernise a design to SMT format, a through-hole wirewound protection

resistor was proving hard to replace without lling a very large area with chip

resistors. TT Electronics developed a solution whereby an axial part is leadformed

and packed in blister tape. The resulting “ZI-form” component can be picked, placed

and reflowed as an SMT part.

Using the Short Form

1. Choose the right technology - page 3

Find the best resistor technology for the set of features your design needs

2. Choose the right product series - pages 3 & 4

Use the SMT and Through Hole selector guides to identify a series which has

the required ratings, precision and value range

3. Choose the right product type - pages 5 to 16

Refer to product tables to select the correct size and link to further data

Or, if you know the product series, use the Quick Find index.

Quick Find

Series Page Series Page Series Page Series Page

1600/1900 9 HVD 7 PTS 15 WDBR-UL 11 (see WDBR)

3810 6 HVP 7 PWC 8 WH 11

4500 6 LCS 5 PWP 9 WHPC 11

4530 7 LHVC 7 RC 13 WHS 9

4800 12 LOB 5 RCP 13 WHS-UL 15

APC 12 LRCS/LVC 5 RHVD 8 WIN 13

ASC 16 LR(F) 5 SC3 10 WL4 16

BCN 16 LRF3W 5 SOT143 13 WMHP 11

BPC 9 LRMA 5 SP20F 14 WMO-S 11

BPR 10 LRZ 16 SPP 14 WPRT 12

CAR 12 MFC 6 SQM 10 WP-S 9

CR 15 MFP 10 SQP 10 WP-SZI 12

DIV23 12 MFR 15 T 8 WPYP 8

DSC 8 MF-S 10 TFHP 11 WRM 14

EBW 5 OAR 6

TJC

15 WRM-HP 14

EMC 14 OARS 6 ULR 6 WRM-HV 14

GCR 16 PCF 13 ULW 14 WSHR 11 (see WDBR)

GHVC 7 PCFH 13 VRW 8 WSM 12

HDSC 8 (see DSC) PCFP 13 W20 11 WSMHP 12

HPDC 10 PCR 13 W30 9

HPWC 8 (see PWC) PFC 15 WA84F 14

HR 7 PFC-D 13 WCM 9

HTCR 10 PFC-HT 15 WCR 16

HVC 7 PR 13 WDBR 11